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WORKS  OF 
J.  MERRIIT  MATTHEWS 

PUBLISHED   BY 

JOHN    WILEY    &    SONS,    Inc. 


Application    of    Dyestuffs    to    Text.Ies,    Paper, 
Leather  and  other  Materials 

768  pages,  6  by  9,   303  figures.     $10.00  7iW. 

The  Textile  Fibres 

Their  Pliysical,  Microscopical,  and  Chemical 
Properties.  Third  edition,  rewritten.  630 
pages,   6  by  9,   141  figures.     $5.00  net. 


APPLICATION 
of  DYESTUFFS 

TO  TEXTILES,   PAPER,    LEATHER 
AND  OTHER  MATERIALS 


BY 

J.  MERRITT   MATTHEWS,  Ph.D. 


NEW  YORK 

JOHN  WILEY  &  SONS,   Inc. 

London:  CHAPMAN  &  HALL,  Limited 
1920 


Copyright,  1920,  by 
J.  MERRITT  IMATTHEWS 


ALL  RIGHTS  RESERVED 


6/23 


PRESS  OF 

BRAUNWORTH  h.    CO. 

BOOK  MANUFACTURERS 

BROOKLYN  N.  Y. 


PREFACE 


The  present  volume  has  been  the  resuU  of  a  comprehensive  and  more 
extended  development  of  the  author's  earlier  book  entitled  "Laboratory 
Manual  of  Dyeing  and  Textile  Chemistry."  The  latter  was  designed  prin- 
cipally as  a  text-book  for  students,  and  necessarily  omitted  a  great  deal  of 
matter  of  more  general  and  practical  interest.  The  present  book,  while 
still  retaining  many  of  the  text-book  features  in  order  to  adapt  it  to  the 
needs  of  the  student,  has  been  greatly  broadened  in  its  scope  so  as  to  appeal 
to  the  interest  of  all  those  concerned  in  the  application  of  dyestuffs. 

Dyestutts  are  most  largely  used  in  the  textile  industries,  and  naturally 
this  field  has  received  the  greatest  attention  at  the  hands  of  the  author, 
but  there  has  also  been  included  a  discussion  of  the  use  of  dyes  in  other 
lines  of  industiy;  though  the  Hmitations  of  space,  as  well  as  the  necessity 
of  maintaining  a  proper  balance  in  the  subjects  considered,  has  precluded 
more  than  a  brief  survey  of  these  interesting  fields. 

The  method  of  presentation,  as  well  as  the  subject  matter  herein  con- 
tained, have  been  the  outcome  of  a  number  of  years  of  teaching  on  the  part 
of  the  author,  supplemented  by  a  larger  number  of  years  of  active  pro- 
fessional practice  in  this  field  of  appUed  chemistry.  Care  has  been  taken 
to  avoid  a  too  purely  scientific  generalization,  else  the  volume  would  lose 
much  of  its  value  for  purposes  of  instruction  and  information.  The  sub- 
ject treated  is  a  technical  one,  and  an  endeavor  has  been  made  to  present 
it  in  a  technical  manner;  that  is  to  say,  definite  facts  have  been  presented 
in  a  definite  form.  To  this  end  an  experimental  outhne  has  been  dis- 
tributed through  the  different  chapters,  both  to  act  as  a  laboratory  guide 
for  the  teacher  and  student  and  also  to  furnish  concrete  examples  to  the 
general  reader. 

The  author  has  endeavored  as  far  as  his  hmitations  permit  to  incor- 
porate in  this  book  the  latest  knowledge  of  the  subject.  In  the  case  of 
dyestuffs,  this  has  been  rather  difficult  at  the  present  time,  owing  to  the 
tremendous  impetus  the  manufacture  of  dyestuffs  has  received  in  both 
America  and  England  during  the  last  few  years,  together  with  the  shutting 
off  from  the  world  of  the  long-used  and  well-known  German  dyes.  This 
condition  has  created  considerable  chaos  in  the  dyestuff  world,  and  there 


vi  PREFACE 

has  also  been  a  great  readjustment  in  the  naming  of  dyestuffs.  In  order 
to  prevent  undue  confusion  as  well  as  the  risk  of  recording  products  that 
may  subsequently  prove  to  be  only  of  a  temporaiy  significance,  the  author 
has  deemed  it  advisable  to  retain  the  names  and  the  dyestuffs  that  were 
well  known  before  the  war  and  which  would  be  easily  and  intelUgently 
recognized  in  the  industry  all  over  the  world.  The  dyestuff  industry  in 
this  country  is  already  well  established  and  the  author  has  great  faith  in 
its  permanence  and  eventual  success;  but  at  the  present  time  this  entire 
industry  is  in  a  state  of  rapid  development  and  constant  flux;  its  products 
and  their  nomenclature  are  constantly  undergoing  radical  changes,  and 
there  still  persists  in  the  entire  trade  a  tendency  to  retain  the  long-estab- 
lished and  familiar  names  of  the  more  general  dye-products.  On  this 
account  the  author  has  been  obliged  to  maintain  a  considerable  degree  of 
conservatism  in  the  selection  of  the  various  dye-products  mentioned  in  the 
course  of  the  book. 

New  Yokk,  February,  1920.  J.  Merritt  Matthews. 


TABLE   OF   CONTENTS 


INTRODUCTION 

FAGB 

1.  General  Definitions 1 

2.  Historical 7 

.3.  Dyes  of  Antiquity  Compared  with  Modern  Dyes 14 

4.  Apparatus  and  Equipment  for  Dye-testing 16 

6.  Practical  Process  of  Dyeing 20 

6.  Water  and  Steam  in  the  Dyehouse 26 

7.  Forms  in  which  Textiles  are  Dyed 31 

8.  Hydro-extracting  and  Drying 33 

9.  After-treatment  of  Dyed  Material 34 


CHAPTER 
CHEMICAL  STUDY  OF  THE  FIBERS 

1 .  Action  of  Acids  on  Textile  Fibers 36 

2.  Action  of  Alkalies 40 

3.  Mercerizing  of  Cotton 41 

4.  Action  of  MetaUic  Salts  on  Fibers 63 

5.  Action  of  Chlorine  Compounds  and  Oxidizing  Agents 54 

6.  Effect  of  Moisture  on  Textile  Fibers 57 

7.  Action  of  Heat  on  Textile  Fibers 61 

8.  Action  of  Hot  Water  on  Wool 63 

9.  Experimental  (1-16) 66 

CHAPTER  II 
SCOURING  THE  TEXTILE  FIBERS 

^.  Impurities  in  Raw  Wool 71 

2.  The  Emulsion  Process  of  Scouring 72 

3.  Use  of  Alkali  in  Scouring 74 

4.  Carbonizing 74 

5.  The  Scouring  of  Woolen  Yarn 75 

6.  The  Scouring  of  Yarns  Containing  Iron 80 

7.  Scouring  Tops 80 

8.  Scouring  Woolen  Piece-goods 82 

X  Soaps  for  Scouring  Wool 87 

vii 


viii  TABLE  OF  CONTENTS 

PAGB 

^0.  BoUing-out  of  Cotton 89 

11 .  The  Impurities  in  Raw  Silk 94 

12.  The  Boiling-off  of  Silk 96 

13.  The  Relation  of  Water  to  Wool  Scouring 100 

14.  Experimental  (17-27) 105 


CHAPTER  III 
BLEACHING  OF  WOOL  AND  SILK 

1.  Bleaching  Wool 107 

2.  Use  of  Sodium  Bisulphite .  108 

3.  Bleaching  Wool  with  Peroxides 110 

4.  Bleaching  Wool  with  Potassium  Permanganate 112 

5.  Bleaching  Silk lU 

6.  Experimental  (28-32) 114 

CHAPTER  IV 
BLEACHING  OF  COTTON 

'i.  General  Methods  of  Cotton  Bleaching 116 

2.  The  Operations  in  Cotton  Bleaching 117 

3.  Boiling-out 117 

4.  Bleaching  with  Hypochlorites 122 

5.  Bleaching  Powder  and  its  Use 125 

6.  The  Acid  Treatment 128 

7.  Washing 128 

8.  Soaping  and  Tinting 129 

9.  Use  of  "Anti-chlor" 131 

10.  Use  of  Acetic  Acid 133 

11.  Bleaching  with  Sodium  Hypochlorite 134 

12.  Bleaching  with  Liquid  Chlorine 136 

13.  Electrolytic  Bleach  Liquors 139 

14.  Bleaching  Loose  Cotton 143 

15.  Bleaching  Cotton  Skein  Yam 144 

16.  Bleaching  Cotton  Warps 144 

17.  Bleaching  Knit  Goods 146 

18.  Experimental  (33-44) 150 

CHAPTER  V 
CLASSIFICATION  OF  DYES 

1.  General  Classification  of  Dyes 154 

2.  Action  of  Dyestuffs  on  the  Textile  Fiber 158 

3.  Action  of  Dyestuffs  on  Wool 159 

4.  Action  of  Dyestuffs  on  Silk 163 

5.  Action  of  Dyestuffs  on  Cotton 164 

6.  Use  of  Mordants 1C6 

7.  The  Pigment  Dyes 169 


TABLE  OF  CONTENTS  j- 

PAQB 

8.  Relation  between  Color  and  Chemical  Constitution 169 

9.  General  Relations  between  the  Fibers  and  the  Methods  of  Dyeing 170 

10.  Experimental  (45-49) I75 

CHAPTER  VI 
APPLICATION  OF  ACID  DYES  TO  WOOL 

1.  General  Characteristics  of  the  Acid  Dyes I77 

2.  Preparation  of  the  Dyebath IgO 

3.  Function  of  the  Chemicals  Employed  in  Dyeing  Acid  Colors 184 

4.  Exhaustion  and  Leveling  Properties Igg 

5.  Calculations  Used  in  Dyeing 187 

6.  General  Remarks  on  the  Dyeing  of  Wool 188 

7.  Dyeing  Wool  in  the  Loose  Stock 188 

8.  Dyeing  Tops  and  Slubbing 190 

9.  Dyeing  Woolen  Yarns 190 

10.  Dyeing  Piece-goods 191 

1 1 .  Experimental  (50-58) I93 

CHAPTER  VII 
APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

1.  Dyeing  of  Silk  with  Acid  Colors I97 

2.  Notes  on  the  Weighting  of  Silk 200 

3.  Dyeing  Cotton  with  the  Acid  Colors 202 

4.  The  After-chromed  Acid  Dyes 206 

5.  On  the  Proper  Storage  of  Dyestuffs 207 

6.  Dissolving  of  DyestuiTs 208 

7.  Action  of  Metals  on  Dyestuff  Solutions 210 

8.  Apparatus  for  Dyeing 211 

9.  Apparatus  for  Dyeing  Cotton  Yarn 212 

10.  Apparatus  for  Dyeing  Woolen  Yarn 213 

11.  Apparatus  for  Dyeing  Silk  Yarn 214 

12.  Influence  of  the  Water  Employed  in  Dyeing 215 

13.  Experimental  (59-67) 219 

CHAPTER  VIII 
REPRESENTATIVE  ACID  DYES 

1 .  Nomenclature  of  Dyestuflfs 222 

2.  Dyestuff  Manufacturers 230 

3.  List  of  the  Principal  Acid  Dyes 232 

4.  Experimental  (68-70) 236 

CHAPTER  IX 
STRIPPING  OF  COLORS;  TESTING  FASTNESS   OF  DYES 

1.  Stripping  of  Dyed  Fabrics ...  237 

2.  Experimental  (71-73) 238 


X  TABLE  OF  CONTENTS 

PAGE 

3.  Fastness  of  Dyes 239 

4.  Experimental  (74-83) 240 

CHAPTER  X 
APPLICATION  OF  BASIC  DYES 

1 .  Characteristics  of  the  Basic  Dyes 247 

2.  Use  of  Basic  Dyes  on  Silk 249 

3.  L'se  of  Basic  Dyes  for  Wool 251 

4.  Experimental  (84-90) 252 

CHAPTER  XI 
BASIC  DYES  ON  COTTON 

1.  The  Use  of  Basic  Colors  on  Cotton 255 

2.  Substances  Employed  for  Mordanting  Cotton 263 

3.  Tartar  Emetic  and  Antimony  Salts 265 

4.  Experimentp.l  (91-96) 267 

CHAPTER  XII 
PRINCIPAL  BASIC   DYES 

1 .  List  of  the  Principal  Basic  Dyes 270 

2.  Notes  on  the  Practical  Dyeing  of  the  Basic  Colors 273 

3.  Experimental  (97-98) 274 

CHAPTER  XIII 
APPLICATION  OF   SUBSTANTIVE  DYES  TO  COTTON 

1.  The  Substantive  Dyestuffs 275 

2.  Use  of  Substantive  Dyes  on  Cotton 276 

3.  After-treatment  of  Substantive  Dyes 281 

4.  Topping  Substantive  Colors  with  Basic  Dyes 284 

5.  Dyeing  Cotton  Warps  in  the  Size 285 

6.  Experimental  (99-113) 286 

7.  List  of  Principal  Substantive  Dyes 290 

8.  Substantive  Dyes  for  After-treatment  with  Bluestone 296 

9.  Substantive  Dyes  for  After-treatment  with  Chrome  and  Bluestone 296 

CHAPTER  XIV 
SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

1 .  The  Substantive  Colors  on  Wool 298 

2.  The  Substantive  Colors  on  Silk 300 

3.  Experimental  (114-122) 302 

4.  Principal  Substantive  Dyes  for  Wool 306 

5.  Principal  Substantive  Dyes  for  Silk 307 


TABLE  OF  CONTENTS  xi 


CHAPTER  XV 
DEVELOPED  DYES  ON  COTTON  AND  SILK 

J^y^  PAGE 

K  The  Production  of  Developed  Colors  on  Cotton 308 

2.  Developers 311 

S^Methods  of  Shading  Developed  Dyes 314 

4r  Application  of  Developed  Dyes  to  Silk 316 

5:"  Coupled  Dyes 317 

6.  The  Naphthol  Colors 320 

7.  Paranitraniline  Red 322 

S.  Notes  Respecting  Developing 329 

9.  Other  Naphthol  Dyes 331 

10.  List  of  Principal  Developed  Dyes 333 

11.  List  of  Dyes  for  Shading 334 

12.  List  of  Dyes  for  Coupling 334 

13.  Experimental  (123-132) 335 


CHAPTER  XVI 
APPLICATION  OF  MORDANT  DYES 

1.  The  Mordant  Dyes 340 

2.  The  Mordanting  of  Wool 341 

3.  Mordanting  with  Chrome 344 

4.  Mordanting  with  Other  Metallic  Salts 347 

5.  Description  of  Mordanting  Methods 349 

6.  Single  Bath  Methods  of  Mordanting 351 

7.  Dyeing  with  Mordant  Colors 352 

8.  Top-chrome  Method 354 

9.  Mono-Chrome  and  Meta-Chrome  Methods 356 

10.  Dyeing  on  Various  Mordants 358 

11.  Experimental  (133-139) 360 

12.  Use  of  Mordant  Dyes  on  Silk 365 

13.  Mordant  Dyes  on  Cotton 365 

14.  Experimental  (140-141) 366 

15.  List  of  Principal  Mordant  Dyes 373 


CHAPTER  XVII 

SULPHUR  DYES 

\.  Nature  of  the  Sulphur  Dyes 374 

t.  Dissolving  the  Sulphur  Dyes 376 

3:  Method  of  Dyeing 377 

4r.  After-treatment  of  Sulphur  Colors 386 

5.  Topping  of  Sulphur  Dyes 388 

6.  Fastness  of  Sulphur  Colors 389 

7.  Apparatus  Used  in  Dyeing  Sulphur  Colors 393 

8.  List  of  Principal  Sulphur  Dyes 401 

0.  Experimental  (142-149) 403 


xii  TABLE  OF  CONTENTS 

CHAPTER  XVIII 
THE  VAT  DYES 

PAGE 

Jf;'Classes  of  Vat  Dyes 405 

2.  Indiso 410 

S.  Methods  of  Dyeiiif?  Indigo 413 

4.  The  Fermentation  Vat 417 

5.  The  Copperas  Vat 422 

6.  The  Zinc  Vat 426 

7.  The  Hydrosulphite  Vat 427 

8.  Indigo  Extract 431 

9.  Synthetic  Indigo 431 

10.  Testing  Indigo  in  the  Fiber 435 

11.  Indigo  Derivatives;  Thio-Indigo  Dyes 436 

12.  Substituted  Indigo  Derivatives 439 

13.  Anthraquinone  Vat  Dyes 441 

14.  The  Carbazol  Vat  Dyes 444 

15.  Experimental  (150-158) 445 

CHAPTER  XIX 
ANILINE  BLACK 

1 .  Chemistry  of  Anihne  Black 451 

2.  Dyeing  of  Aniline  Black;  One-bath  Method 453 

3.  Aged  or  Oxidized  Black 455 

4.  Steam  Black  with  Aniline 459 

5.  Aniline  Black  on  Other  Fibers 460 

6.  Diphenyl  Black 461 

7.  Paramine  Brown 462 

8.  Experimental  (159-165) ,', 463 

CHAPTER  XX 
USE  OF  LOGWOOD  IN  DYEING 

1 .  General  Use  of  Natural  Dyes 470 

2.  Logwood 471 

3.  Dyeing  on  Wool 476 

4.  Dyeing  on  Cotton 479 

5.  Dyeing  on  Silk 481 

6.  Reactions  of  Logwood 482 

7.  Detection  of  Logwood  in  the  Fiber 482 

8.  Experimental  (166-187) 484 

CHAPTER  XXI 
THE  MINOR  NATURAL  DYES 

1.  Fustic 492 

2.  Osage  Orange 495 

3.  Madder 496 

4.  Archil 498 


TABLE  OF  CONTENTS  xiii 

PAGH 

5.  Quercitron 500 

6.  Catch 501 

7.  Cochineal 505 

8.  Weld 507 

9.  Persian  Berries 508 

10.  Turmeric 508 

1 1 .  Kermes 509 

12.  Lac  Dye 509 

13.  E.xperimental  (188-193) 510 

CHAPTER  XXII 
THE  MINERAL  DYESTUFFS 

1.  General  Use  of  Mineral  Dyes 513 

2.  Mineral  Khaki  on  Cotton 515 

3.  The  Minor  Pigment  Colors . 515 

4.  Experimental  (194-207) 516 

CHAPTER  XXIII 
DYEING  OF  FABRICS  CONTAINING  MIXED  FIBERS 

1.  Character  of  Material 524 

2.  Fabrics  of  Wool  and  Cotton  on  Union  Goods 524 

3.  Detection  and  Estimation  of  Cotton  and  Wool  in  Mixed  Goods 528 

4.  Properties  of  Union  Goods 530 

6.  Bleaching  of  Union  Goods 530 

6.  Action  of  Dyestuffs  on  Union  Goods 631 

7.  Preparation  of  Union  Fabrics  for  Dyeing 533 

8.  The  Dyeing  of  Union  Fabrics 534 

9.  Dyeing  Process  for  Union  Goods 537 

10.  Two  Color  Effects 541 

11.  Classification  of  Dyes  for  L^^nion  Goods 541 

12.  After-treatment  of  Union  Goods 546 

13.  The  Dyeing  of  Wool  Plush 547 

14.  Experimental  (208-227) 648 

15.  Dyeing  of  Wool-Silk  Materials 553 

16.  Classification  of  Dyes  for  Wool-Silk  Fabrics 556 

17.  Silk-Cotton  Materials 660 

18.  Dyeing  of  Silk-Cotton  Fabrics 561 

19.  Dyeing  Processes 562 

20.  Classification  of  Dyes  for  Silk-Cotton  Materials 564 

21.  Experimental  (228-233) 567 

CHAPTER  XXIV 

APPLICATION  OF  DYES  TO  MINOR  VEGETABLE  FIBERS;  LINEN, 
RAMIE,  HEMP,  JUTE,  AND  ARTIFICIAL  SILK. 

1.  The  Minor  Vegetable  Fibers 570 

2.  The  Dj-eing  of  Linen 571 


xiv  TABLE  OF  CONTENTS 

FAOB 

3.  The  Dyeing  of  Ramie 575 

4.  The  Dyeing  of  Jute 575 

5.  The  Dyeing  of  Coir 577 

6.  The  Dyeing  of  Hemp 578 

7.  Dyeing  of  Artificial  Silk 578 

CHAPTER  XXV 
THEORY  OF  DYEING 

1 .  General  Theory  of  Dyeing 582 

2.  Theory  of  Dyeing  in  Relation  to  Pigment  Colors 596 

3.  Theory  of  Dyeing  in  Relation  to  Compound  Shades 598 

4.  Theory  of  Dyeing  in  Relation  to  Mixed  Fibers 599 

5.  Different  Factors  in  Theory  of  Dyeing 600 

6.  Theory  of  the  Mordanting  Process 601 

7.  Experimental  (235-238) 604 

CHAPTER  XXVI 
TESTING  THE  FASTNESS  OF  COLORS 

1 .  Fastness  of  Dyes 607 

2.  Testing  Fastness  of  Colors  Dyed  on  Wool 608 

3.  Testing  Fastness  of  Colors  Dyed  on  Cotton 616 

4.  Testing  Fastness  of  Colors  Dyed  on  Silk 618 

5.  Tabulation  of  Fastness  Required  on  Various  Classes  of  Material 619 

CHAPTER  XXVII 
APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

1.  The  Dyeing  of  Leather 624 

2.  The  Dyeing  of  Paper 630 

3.  The  Dyeing  of  Furs 632 

4.  The  Dyeing  of  Feathers 635 

5.  The  Dyeing  of  Straw 636 

6.  The  Dyeing  of  Wood  Chip  and  Plait 638 

7.  The  Dyeing  of  Horse-hair  and  Bristles 639 

8.  The  Dyeing  of  Human  Hair 639 

9.  The  Dyeing  of  Artificial  Flowers *41 

10.  The  Dyeing  of  Wood 643 

11.  The  Dyeing  of  Celluloid 644 

12.  The  Dyeing  of  Button  Material 645 

CHAPTER  XXVHI 

APPLICATION  OF  DYESTUFFS  IN  THE  PREPARATION  OF  LAKES, 

INKS,  ETC. 

1 .  Preparation  of  Color-Lakes 648 

2.  Preparation  of  Spirit  Lakes 658 


TABLE  OF  CONTENTS  xv 


FASE 


3.  The  Dyeing  of  Soap 659 

4.  Dyestuffs  for  Inks ggQ 

5.  Dyestuffs  for  Typewriter  Ribbons 663 

6.  Dyeing  of  Perfumes 6g3 

7.  Dyeing  of  Candles,  Oils  and  Waxes 663 

8.  Use  of  Dyestuffs  for  Coloring  Food  Products 664 

9.  Use  of  Dyestuffs  as  Indicators 665 

10.  Use  of  Dyes  tuffs  in  Medicine 665 


CHAPTER  XXIX 
TESTING   OF  DYESTUFFS 

1.  To  Obtain  the  Money  Value  of  a  Dyestuff  Sample 666 

2.  To  Determine  if  a  Dyestuff  is  Simple  or  Mixed 668 

3.  To  Determine  the  Class  to  which  a  Dyestuff  JBelongs 669 

4.  Chemical  Method  of  Distinguishing  between  Acid  and  Basic  Dyes 672 

5.  Detection  of  Adulterations  in  Dyestuffs 672 

6.  Determination  of  the  Capillary  Speed  of  Dyestuffs 676 


CHAPTER  XXX 
MISCELLANEOUS  TESTS  IN   DYEING 

1 .  The  Amount  of  Dyestuff  Necessary  for  a  Full  Shade 678 

2.  To  Determine  the  Degree  of  Exhaustion  of  the  Dyebath 678 

3.  To  Determine  the  Correct  Amount  of  Mordant  to  Use 679 

4.  To  Determine  the  Degree  of  Exhaustion  of  the  Mordant  Bath 679 

5.  To  Show  the  Dichroic  Property  of  a  Dyestuff 680 

6.  Effect  of  Dichroism  in  the  Compounding  of  Shades 681 


CHAPTER  XXXI 
CHEMICAL  REACTIONS  OF  DYESTUFFS 

1.  Identification  of  Dyes 682 

2.  Solubility  Tests 682 

3 .  Reaction  with  Sulphuric  Acid 682 

4.  Reaction  with  Hydrochloric  Acid 683 

5.  Reaction  with  Nitric  Acid 683 

6.  Reaction  with  Sodium  Hydrate 683 

7.  Reaction  with  Ammonia 683 

8.  Reaction  with  Sodium  Carbonate 684 

9.  Reaction  with  Tannin  Reagent 684 

10.  Reaction  with  Alum 684 

11.  Reaction  with  Potassium  Bichromate.  .  .• 684 

12.  Reaction  with  Ferric  Chloride 684 

13.  Reaction  with  Stannous  Chloride 684 


XVI  TABLE  OF  CONTENTS 

PAGE 

14.  Reaction  with  Bleaching  Powder 684 

15.  Reaction  with  Zinc  Dust 685 

16.  Reaction  with  Zinc  Dust  and  Acetic  Acid 685 


CHAPTER  XXXII 
ANALYSIS  OF  TEXTILE  FABRICS 

1.  To  Determine  the  Amount  of  Wool  and  Cotton  in  a  Fabric 687 

2.  Analysis  of  Fabric  Containing  Silk  and  Cotton 687 

3.  Analysis  of  Fabric  Containing  Wool  and  Silk 688 

4.  Analysis  of  Fabric  Containing  Wool,  Silk  and  Cotton 688 

5.  Distinction  between  True  Silk  and  Artificial  Silk 688 

6.  To  Distinguish  between  Cotton  and  Linen 689 

7.  To  Distinguish  between  True  Silk  and  Tussah  Silk 689 

8.  To  Test  if  Cotton  Has  Been  Mercerized 690 

9.  To  Test  if  Silk  Has  Been  Weighted  with  Tin  Salts 690 

10.  Estimation  of  Sizing  and  Dressing  Materials  in  a  Fabric 691 

11.  Conditioning  of  Textile  Materials 691 

12.  Estimation  of  Oil  and  Grease  in  Fabrics 692 

13.  Detection  of  Mineral  Oil  in  Textile  Fabrics 692 

14.  Detection  of  Rosin  Oil  in  Textile  Fabrics 692 

15.  Estimation  of  Mineral  Matter  in  a  Fabric 692 

16.  Determination  of  the  Nature  of  Sizing  on  a  Fabric 692 

17.  Determination  of  the  Nature  of  Mordants  on  Woolen  Fabrics 694 

18.  Determination  of  the  Nature  of  Mordants  on  Cotton  Fabrics 696 

19.  Analysis  of  Black  Dyed  Cotton 697 

CHAPTER  XXXIII 
USEFUL  DATA  FOR  DYERS  AND   TEXTILE  CHEMISTS 

1 .  Hydrometers 701 

2.  Equivalents  of  Common  Use  in  Measuring 703 

3.  Conversion  Tables 704 

4.  Thermometry 706 

5.  Comparison  of  Relative  Strengths  of  Chemicals 706 

6.  Tables  of  the  Strengths  and  Densities  of  Various  Solutions 707 

7.  Useful  Data  for  Calculations  in  Dyeing 712 

8.  Tables  for  Calculations  in  Dyeing 715 

BIBLIOGRAPHY 
Literature  of  Dyeing,  Bleaching,  and  Textile  Chemistry 733 

INDICES 

Experiment  Index 7,51 

Subject  Index 755 


APPLICATION  OF  DYESTUFFS 


INTRODUCTION 

1.  General  Definitions — The  term  dyeing  is  used  almost  exclusively 
with  reference  to  the  textile  industry,  and  it  is  in  this  sense  alone  that  it 
shall  here  be  employed.  Dyeing  means  to  impart  to  the  fibrous  sub- 
stances, fabric,  yarn,  or  other  textile  material,  a  color  which  shall  possess 
certain  qualities,  among  which  may  be  mentioned  imiformity  and  stability 
towards  washing,  exposure,  etc.  As  textile  materials  are  composed  of 
various  fibers,  dyeing  really  refers  more  especially  to  the  coloring  of  the 
fibers  of  which  the  textile  consists.  The  chief  fibers  which  find  an  exten- 
sive application  in  the  manufacture  of  textiles  are  wool,  silk,  and  cotton, 
and  as  the  methods  of  dyeing  these  fibers  are  radically  different,  it  becomes 
necessary  to  classify  the  study  of  the  phenomena  of  dyeing  under  the 
separate  subjects  of  wool  dyeing,  silk  dyeing,  and  cotton  dyeing. 

Dyeing,  in  the  proper  sense  of  the  word,  has  a  deeper  meaning  than 
that  of  merely  imparting  a  color  to  the  fibers;  the  color  must  be  uni- 
formly distributed  throughout  the  substance  of  the  fiber,  and  not  merely 
be  a  coating  on  its  surface.  The  latter  would  be  classified  under  the  term 
of  painting  and  not  dyeing.* 

In  order  that  the  color  shall  penetrate  into  the  substance  of  the  fiber, 
the  coloring  matter  must  be  applied  in  the  form  of  a  solution.  Herein 
lies  the  difference  between  dyestuffs  and  pigments;  the  former  are  colored 
bodies  of  a  soluble  nature,  usually  complex  derivatives  of  carbon,  where- 
as the  latter  are  insoluble  and  mostly  of  mineral  origin.  But  all  soluble 
colored  substances  are  not  dyestuffs;    a  solution  of  copper  sulphate,  for 

*  The  distinction  between  painting  and  dyeing  is  that  the  former  is  the  application 
of  an  adhesive  pigment  to  the  surface  of  a  body  of  almost  any  nature,  whereas  dyeing 
consists  in  coloring  the  actual  substance  of  a  body  by  the  use  of  certain  materials  pos- 
sessing tinctorial  properties  and  known  as  dyestuffs.  When  a  very  slight  amount 
of  dyestuff  is  applied  to  the  material,  the  process  is  usually  known  as  tinting,  as  when 
a  bleached  white  is  tinted  with  a  blue  coloring  matter  to  give  it  a  slight  bluish  tone, 
or  when  white  cotton  is  given  a  very  pale  shade  of  brown  in  order  to  simulate  the  par- 
ticular tint  of  Egyptian  cottos.  Staining  is  a  special  term  given  to  the  coloring  of 
certain  substances  with  dyestuflf  solutions,  as  in  the  coloring  of  paper,  marble,  ivory,  etc. 


2  INTRODUCTION 

instance,  possesses  a  deep  blue  color;  potassium  bichromate  in  solution 
has  a  deep  orange-j'ellow  color;  if  wool  be  saturated  with  these  solutions, 
it  will  acquire  a  blue  or  a  j'ellow  color,  as  the  case  msLy  be,  but  this  color 
can  be  readilj-  removed  by  washing  with  water,  and  we  do  not  consider 
the  wool  as  being  dj-ed,  the  color  in  this  case  only  being  due  to  the  fact 
that  some  of  the  colored  solution  is  for  the  time  being  retained  in  the 
interstices  between  the  fibers.  A  solution  of  ]\Iagenta  possesses  a  beau- 
tiful bluish  red  color;  if  wool  be  impregnated  with  this  solution,  it  will 
acquire  a  similar  color,  and  this  color  will  persist  after  even  a  long-con- 
tinued washing,  and  the  wool  is  said  to  be  dyed  bj-  the  Magenta.  In 
this  latter  case  the  particles  of  coloring  matter  have  become  fixed  in  the 
substance  of  the  fiber  in  an  insoluble  form,  so  that  it  cannot  be  removed 
by  simple  means.  The  wool  is  said  to  possess  an  "  affinitj^  "  for  the  dye- 
stuff — in  other  words,  it  combines  with  the  coloring  matter  and  becomes 
permanently  dyed  thereby.  It  is  plain  that  neither  the  copper  sulphate 
nor  the  potassium  bichromate  would  be  called  a  dyestuff,  whereas  Ma- 
genta would  be  so  designated.  A  dyestuff,  then  may  be  defined  as  a  sol- 
uble substance  capable  of  miparting  a  permanent  color  to  the  textile  fibers. 

So  far,  the  subject  of  dyeing  includes  two  objects  for  our  consider- 
ation, namely,  the  fiber  and  the  dj^estuff.  The  process  of  dyeing,  how- 
ever, is  rare]}'  so  simple  that  it  consists  only  of  impregnating  the  fiber 
with  a  solution  of  the  dj^estuff;  there  are  other  essentials  which  must 
be  considered.  Various  chemical  agents  have  to  be  emploj^ed  in  con- 
nection with  most  of  the  dyestuffs  to  yield  the  proper  results,  and  the 
nature  and  action  of  these  have  to  be  understood  in  order  to  have  a  clear 
insight  into  the  process  of  dyeing. 

The  study  of  dj'eing  is  really  a  specialized  branch  of  chemistry;  for 
not  only  are  the  processes  themselves  more  or  less  chemical  ones,  but  a 
kno^-ledge  of  the  various  materials  employed  is  essentially  a  knowledge 
of  chemistiy.  Dyeing  as  a  science,  then,,  is  but  a  branch  of  applied  chem- 
istry, which  has  for  its  subject  the  study  of  the  fiber,  the  dyestuffs  and 
other  necessary  chemicals,  as  well  as  iho  chemical  reactions  by  which  the 
process  is  carried  out. 

Textile  printing  is  really  a  specialized  department  of  dyeing  in  which 
the  color  is  applied  to  certain  portions  only  of  the  fabric,  usually  with 
certain  definite  pattern  effects.  The  processes  in  the  main  are  about 
the  same  as  in  ordinary'  dyeing,  the  chief  differences  consisting  in  the 
mechanical  methods  employed  in  applying  the  color.  The  same  is  also 
true  of  the  many  special  methods  used  in  fancy  dyeing,  such  as  spray- 
dyeing,  batik,  tie-dyeing,  stencil  dyeing,  etc.  The  nature  of  the  fun- 
damental operations  in  all  cases  is  the  same. 

Mention  of  the  latter  methods  of  using  dyestuffs  for  ornamental  and 
decorative  purposes  brings  up  the  question  of  craft  dyeing,  or  what  might 


CRAFT   DYEING 


be  termed  the  artistic  use  of  dyes  and  processes  of  application  to  produce 
special  objects  of  beauty  and  artistic  value.  The  ordinary  dyer  in  the 
mill  or  cl3'ehouse  is  primarily  concerned  only  with  the  proper  produc- 
tion of  a  certain  color  on  so  many  yards  of  cloth  or  so  many  pounds  of 
yarn  or  loose  fiber.  His  chief  problem  is  the  matching  of  shades,  and 
the  obtaining  of  a  uniform  color 
of  certain  specified  qualities  of 
fastness  at  the  minimum  of  cost. 
The  craft  dyer,  on  the  other  hand, 
works  with  an  entirely  different 
purpose  in  view.  He  (or  she) 
endeavors  to  produce  colors  and 
color  combinations  on  a  fal^ric 
more  with  reference  to  the  par- 
ticular use  of  the  material  being 
dyed,  and  at  the  same  time  try- 
ing to  put  into  the  work  some 
form  of  artistic  expression,  using 
the  color  as  a  component  of 
design.  The  ordinary  dyer,  then, 
is  merely  an  artisan,  while  the 
dye-craftsman  attempts  to  be 
also  an  artist. 

In  ancient  and  medieval  days, 
when  the  division  of  labor  was 
not  so  finely  adjusted  as  at  the 
present  time,  the  dj-er  was  more 
closely  in  contact  with  the  fin- 
ished article  that  his  work  helped 
to  decorate,  and  in  consequence 
he  was  more  a  craftsman  and 
artist  than  at  present.  Craft 
dyeing  in  this  country  has  re- 
ceived an  awakened  interest  on 
account  of  the  European  War, 
which  brought  about  a  wide  in- 
terest in  the  manufacture  of 
dyestuffs   on    this    side    of    the 

Atlantic.  Owing  to  many  fancy  textiles  from  Europe  being  taken  out 
of  trade  I)}'  the  war,  there  was  an  opportunity  in  this  country  to  develop 
various  lines  of  artistic  dyeing  in  a  market  free  from  European  competi- 
tion, and  as  a  result  this  form  of  craft  has  been  able  to  get  fairly  well 
established. 


Fig. 


1. — Batik  from  India. 
C.  E.  Pellew.) 


(Courtesy  of 


4  INTRODUCTION 

Dyeing  in  the  batik  style  of  applying  the  color  to  design  has  been 
undertaken  by  a  number  of  color  artists,  and  very  laudable  and  excellent 
work  has  been  turned  out.  It  is  also  true  that  a  number  of  amateurs 
and  half-baked  artists  have  entered  this  field  with  little  or  no  knowledge 
of  the  possibilities  of  dyeing  and  with  little  or  no  skill  in  technique  or 
ability  in  design,  and  as  a  result  they  have  turned  out  some  horrible 
examples  of  bad  taste  both  in  form  of  design  and  in  combinations  of  color. 
Originality  of  idea  and  highly  developed  skill  in  technique  are  just  as 


Fig.  2.— Tietl-und-Dyed  Work.     (Courtesy  of  C.  E.  Pellew.) 


essential  in  producing  good  results  in  this  form  of  color  art  as  in  paint- 
ing or  other  form  of  art  expression. 

The  batik  style  is  generally  applied  to  cloth  for  a  specific  use  in  a  spe- 
cial garment  or  decorative  fabric,  and  the  design  and  color  effects  are 
adjusted  to  meet  the  requirements  of  the  particular  piece.  For  example, 
this  method  of  dj^eing  is  applied  largely  to  silk  goods  used  in  making 
ladies'  waists  or  gowns;  in  scarfs,  draperies,  and  hangings  for  purposes 
of  interior  decoration,  etc. 

The  tie-dyeing  style  is  also  employed  both  by  itself  and  in  connec- 
tion with  batik  for  the  same  purposes.  Like  batik,  tie-dyeing  also  re- 
quires a  skillfully  developed  technique  of  handling  in  order  to  obtain 


CRAFT  DYEING  5 

proper  results,  otherwise  very  crude  designs  will  be  produced.  As  both 
of  these  styles  often  require  the  dyeing  of  one  color  over  another,  the 
operator  must  have  an  intimate  knowledge  of  such  color  combinations 
in  order  to  obtain  the  proper  artistic  effects.  Also  in  tie-dyeing  consider- 
able ingenuity  has  to  be  exercised  in  forming  ties  in  the  cloth  which  will 
yield  harmonious  and  properly  balanced  designs;  this  requires  an  origi- 
nality of  handiwork  which  usually  takes  considerable  experience  to  develop. 
The  mistake  is  often  made  by  the  amateur  that  any  odd  effect  is  artistic, 
but  this  is  far  from  being  the  case.  Just  what  constitutes  an  artistic 
effect  is  perhaps  very  difficult  to  describe,  and  no  doubt  the  difference 
between  good  taste  and  bad  taste  is  instinctive  and  can  be  cultivated  only 
through  experience. 

Application  of  dyes  by  means  of  stencils  is  in  reahty  a  form  of  print- 
ing by  hand,  using  the  stencil  to  obtain  the  pattern  and  the  brush  to  apply 
the  color  instead  of  printing  blocks.  Stencil  work  is  susceptible  of  very 
artistic  effects  and  originality  of  designs,  as  are  witnessed  in  the  celebrated 
Japanese  stencils  to  be  foun4  among  the  many  art  collections  of  our 
country.  Stencil  work  is  especially  adaptable  to  craft  dyeing  where 
personal  talent  and  handwork  are  the  distinguishing  features.  The  ap- 
plication of  color  in  stencil  work  which  is  fast  requires  special  methods 
of  dyeing  and  treatment,  however,  that  necessitate  an  intimate  knowl- 
edge of  the  properties  of  dyes  tuffs  and  mordants.  Without  this  knowl- 
edge and  its  proper  practical  application,  the  colors  obtained  in  stencil 
work  will  be  little  more  than  surface  paints  and  not  real  dyeings  of  a  satis- 
factory degree  of  fastness  to  light  and  washing. 

The  field  for  craft  dyeing  in  this  country  is  a  broad  one,  and  there  is 
a  large  and  appreciative  public  ready  to  absorb  real  artistic  productions 
at  a  price  which  is  helpful  in  developing  and  encouraging  the  art.  On 
the  other  hand,  this  form  of  craft  has  a  strong  appeal  to  the  dilettante 
and  egregious  amateur,  with  the  result  that  there  is  danger  of  a  flood  of 
poorly  executed  and  badly  designed  productions  submerging  the  really 
good  things  in  this  line.  As  a  rule,  textile  and  color  chemists,  as  well 
as  the  expert  colorists  of  the  dyestuff  factories,  have  given  little  or  no 
consideration  to  these  possibilities  in  craft  dyeing,  believing  it  to  be  too 
small  and  unimportant  a  line  on  which  to  waste  time  and  labor.  This 
may  be  somewhat  true  if  the  quantity  of  dyestuffs  consumed  is  taken  as 
a  measure  of  its  importance,  for  in  this  respect  craft  dyeing  uses  a  very 
small  proportion  of  dyestuffs  in  comparison  with  the  regular  fines  of  dye- 
ing. It  deals  more  with  the  dyeing  of  goods  by  the  square  foot  than  by 
the  thousands  of  yards,  and  probably  the  country's  entire  consumption 
of  dyestuff  in  craft  dyeing  would  not  equal  that  of  one  moderately  sized 
dyehouse  or  mill.  But,  on  the  other  hand,  the  color  chemist  as  well  as 
the  dyestuff  manufacturer  should  realize  that  in  craft  dyeing  we  have 


6 


INTRODUCTION 


the  possibility  of  reaching  into  reahns  of  color  art  that  is  not  present 
in  ordinary'  trade  dyeing.  There  is  also  the  germ  of  originality  and  cre- 
ative purpose  that  may  lead  to  yet  undiscovered  fields  in  dyeing,  that  may 
eventually  widen  out  the  application  and  use  of  dyestuffs  in  general. 

As  a  background  to  the  main  province  of  dyeing,  it  is  well  to  develop 
'md  encourage  this  matter  of  craft  dyeing  as  far  as  possible,  and  the  color 


Fig.  3. — Japanese  Stencil.     (Courtesy  of  H.  Steigner.) 


chemist  and  d3'cstuff  producer  should  give  it  their  serious  attention.  To 
the  chemist  it  should  prove  an  attractive  field  in  the  devising  of  ingenious 
methods  of  applying  dyestuffs  and  mordants  to  produce  effects  by  hand 
treatment  that  are  hardly  thought  of  by  the  ordinaiy  dj^er.  And  there 
is  always  the  possibility  that  many  of  these  processes  ma}''  be  adapted 
subsequently  to  a  large-scale  production  that  will  give  results  of  a  higher 
degree  of  quality  and  taste. 


EARLY  HISTORY  OF  DYEING  7 

2.  Historical. — Considered  from  an  historical  point  of  view,  dyeing 
is  as  old  as  the  textile  industry  itself,  and  this  antedates  the  written  doc- 
uments of  human  history.  Closely  connected  with  the  utilitarian  desire 
o'  human  beings  to  clothe  themselves  from  the  inclemencies  of  the  weather 
is  the  desire  for  artistic  effects  to  be  obtained  in  coloring  the  materials 
of  which  these  protective  coverings  are  made.  From  Greek  mythology 
we  learn  that  Ariadne,  the  goddess  of  spinning  and  weaving,  was  the 
daughter  of  Idon  the  dyer  of  wool,  a  truly  interesting  chronological 
comparison,  and  one  showing  how  intimately  the  art  of  dyeing  was  con- 
nected with  its  sister  arts. 


Fig.  4. — Dyeing  in  Ancient  Egypt. 

Perhaps  the  earliest  authentic  records  we  have  concerning  the  indus- 
trial life  of  the  ancient  nations  are  those  contained  in  the  historical  classics 
of  the  Chinese ;  in  these  we  find  mention  of  the  dyeing  of  silk  in  various 
colors  as  far  back  as  2600  B.C.  The  dyestuffs  employed  were  those 
obtained  from  various  plants.  Dyeing,  together  with  its  related  industry, 
printing,  appears  to  have  been  practiced  at  very  early  times  by  the 
various  East  Indian  nations,  long  before  their  migrations  led  to 
the    settlement    of    Asia    Minor    and    Europe.*      Remnants    of    dyed 

*  The  ancient  Hindoos  were  evidently  acquainted  with  a  large  number  of  vegetable 
coloring  matters;  of  the  nature  and  properties  of  these,  however,  we  know  little  or 
nothing,  for  even  the  native  dyes  which  are  employed  in  India  at  the  present  time  have 


8  INTRODUCTION 

fabrics  of  great  antiquity  have  also  been  recovered  from  Eg>'ptian 
tombs.* 

As  to  the  coloring  matters  employed  by  the  ancient  peoples  in  dyeing, 
nearly  all  were  of  vegetable  or  mineral  origin,  and  many  were  more  or  less 
of  merely  local  occurrence.  The  dyer  went  out  into  the  forest  and  collected 
the  plants  which  had  been  found  to  possess  tinctorial  properties,  extracted 
the  coloring  matter  bj'  boiling  these  in  water,  and  emploj-ed  this  liquid 
decoction  as  the  dyebath.  The  use  of  mordants  was  also  known,  for  the 
majority  of  the  vegetable  coloring  matters  required  the  previous  appli- 
cation of  a  suitable  mordant  in  order  subsequently  to  develop  and  render 
permanent  the  color  obtained  in  the  dyebath.  In  fact,  it  was  known  that 
by  using  mordants  of  different  metals  different  colors  could  be  produced 
with  the  same  dyestuff,  and  in  Pliny  we  find  a  description  of  how  the 
EgA'ptians  obtained  variegated  colors  on  a  fabric  by  d3'eing  it  in  one  oper- 
ation with  a  single  d^'estuff,  having  previously  applied  metallic  com- 
pounds in  such  manner  as  to  obtain  the  desired  effect. 

Indigo  was  known  in  very  early  times  and  was  extensively  employed, 
especially  in  Asiatic  countries,  for  the  production  of  blue  colors.  Red 
was  obtained  from  various  vegetable  extracts  and  also  from  the  kermes 
insect,  which  somewhat  resembles  cochineal;  Madder  was  also  used.f 
Safilower,!  Saffron,  Weld,  Persian  Berries,  and  other  vegetable  products 
were  employed  for  d^-eing  scarlet  and  j^ellow. 

At  the  opening  of  European  history  the  Phoenicians  appear  to  have 
been  most  renowned  for  their  skill  in  dj-eing,  and  their  beautifully  colored 
fabrics  became  articles  of  extensive  trade  with  other  nations.  The  cele- 
brated "  Tyrian  purple  "  appears  to  have  had  its  origin  among  the  Phoe- 
nicians, and  its  beauty  and  high  price  made  it  a  badge  of  royalty.  §     This 

been  very  little  studied.  The  process  of  dyeing  Indigo  by  means  of  the  fermentation 
vat  appears  to  have  had  its  origin  in  India. 

*  A  garment  dyed  with  Indigo  has  been  found  in  Thebes  dating  from  3500  B.C.,  and 
archeological  researches  have  shown  that  the  Egyptians  dyed  iron  buff  and  used  the 
yellow  coloring  matter  of  the  safflower  in  dyeing  as  early  as  2.500  b.c. 

t  The  scarlet  color  of  the  Tabernacle  curtains  of  the  Bible  was  no  doubt  produced 
with  Kermes.  This  material  was  known  to  the  ancients  as  "kermes  berries"  and  was 
thought  to  be  a  vegetable  product,  and  it  was  not  until  the  eighteenth  century  that  it 
was  recognized  as  an  insect  similar  to  cochineal.  Kermes  was  known  to  the  Egj'ptians 
before  the  days  of  Moses,  and  was  said  to  have  been  discovered  by  the  Phoenicians.  By 
the  Hebrews  it  was  called  Tola,  and  by  the  Egyptians  worm  dye.  In  Persia  its  color  was 
more  sought  after  even  than  the  Tyrian  purple. 

I  Safflower  was  used  by  the  Egyptians  to  dye  silk  a  brilliant  but  rather  fugitive 
scarlet.  The  Greeks  in  early  times  used  it  as  a  royal  color  and  even  in  ancient  Ireland 
(in  fact  up  to  the  seventeenth  century)  the  king's  mantle  was  dyed  with  it. 

§  A  very  complete  description  is  given  by  Pliny  in  various  parts  of  his  "History  of 
Nature"  concerning  the  nature  of  the  Tyrian  purple  and  the  methods  employed  for 
obtaining  it  from  the  shell-fish,  as  well  as  the  means  of  applying  the  color  to  fabrics. 


DYEING   IN   GREECE   AND   ROME 


9 


coloring  matter  was  obtained  from  certain  shell-fish  which  were  collected 
along  the  coast,  and  recent  research  has  shown  that  this  dyestuff  was 
dibromindigo,  a  coloring  matter  which  has  now  been  prepared  synthetic- 
ally, as  one  of  the  modern  "vat"  dyestiiffs.*  According  to  Phny, 
the  Greeks,  at  the  time  of  Alexander  the  Great,  were  acquainted  with 
the  art  of  d3'eing  wool  in  purple  and  other  colors,  and  also  of  dyeing  linen 
in  black,  yellow,  l)lue,  and  green  colors  which  were  fast  to  washing.  Plut- 
arch tells  us  that  in  Rome  dyeing  was  carried  on  as  a  handicraft,  which 
Numa  Pompilius  endeavored  to  encourage  and  foster  by  establishing  a 
college  in  the  interest  of  this  art.  This  "  collegium  tinctorum  "  is  inter- 
esting to  us  as  being  probably  the  first  school  of  dyeing  ever  established. 


Fig.  5. — Dyeing  Cotton  Black.      (Eighteenth  Century.) 

The  Romans  were  acquainted  with  a  number  of  different  coloring 
matters,  and  divided  them  into  major  dyes  and  minor  dyes;  the  first 
were  used  for  dyeing  garments  for  both  sexes,  whereas  the  second  were 
employed  solely  for  either  men  or  women  as  the  case  might  be.  Yellow, 
for  instance,  was  only  used  for  dyeing  bridal  garments.  This  was  truly 
a  remarkable  sociological  classification  of  dyestuffs.  Pliny  gives  us  a 
description  of  the  following  materials  used  in  dyeing  by  the  people  of 
his  time.  He  describes  alum,  and  classifies  it  into  white  and  black  vari- 
eties; from  his  description,  however,  this  term  must  be  taken  to  include 
not  only  the  ordinary  alum  which  we  recognize,  but  also  soda,  which  oc- 
curred in  natural  deposits  in  various  localities,  and  probably  several  other 
such  salts.  We  understand  from  Pliny,  however,  that  the  Romans  were 
acquainted  with  the  art  of  applying  metalhc  mordants  to  wool;    they 

*  See  Friedlander,  Berichte  der  deutschen  Chem.  Gesellschaft,  1909,  p.  765.  The 
dyestuff  was  obtained  directly  from  the  shell-fish,  12,000  being  used  in  the  research, 
with  a  total  yield  of  1.4  grams  of  pure  color. 


10 


INTRODUCTION 


appeared  to  have  employed  a  decoction  of  sea-grass  for  fixing  the  alum 
mordant,  nmch  after  the  manner  that  cow  dung  was  employed  by  dyers 
up  to  even  rather  recent  times.  The  Romans  were  also  acquainted  with 
the  use  of  tannin  as  a  mordant  in  dyeing  black,  using  a  decoction  of  oak 
bark  for  this  purpose.  Among  the  various  dyewoods  mentioned  by 
Pliny  are  genista  (probably  corresponding  to  our  Flavine)  for  yellow, 
elderberry  and  walnut  shells  for  brown,  Woad  for  blue.  The  latter  was 
applied  in  a  vat  somewhat  like  Indigo;  the  dye  indicum  is  also  mentioned, 
but  whether  this  was  identical  with  true  Indigo  or  not  is  a  disputed  point. 


Fig.  6.— Skein  Dyer.     (Middle  Ages.) 


Red  colors  were  obtained  from  madder  root;  from  the  root  of  the  red 
cabbage — the  latter,  in  fact,  is  employed  in  Russia  even  to  the  present 
time,  and  is  known  in  trade  under  the  name  of  alkanna;  while  Kermes 
was  used  for  dyeing  a  purplish  red.  Purple  was  dyed  after  the  manner 
of  the  Tyrian  purple,  from  the  coloring  matter  extracted  from  a  certain 
shell-fish. 

The  Venetians  appear  to  have  been  the  first  of  the  more  modern  Euro- 
pean nations*  to  acquire  skill  in  the  art  of  dyeing,  or  in  fact  of  any 

*  Benjamin  of  Tudelo  informs  us  that  a  numl)er  of  dyehouses  existed  in  and  around 
Jerusalem  during  the  twelfth  century,  and  that  dyeing  v/as  entirely  in  the  hands  of  the 
Jews. 


INTRODUCTION   OF  INDIGO 


II 


of  the  textile  branches.*  From  Venice  the  art  of  d3^eing  was  gi-adually 
developed  throughout  the  other  European  countries  and  soon  reached 
a  high  stage  of  excellence  in  Holland,  France,  England,  and  Germany. 
Though  Indigo  was  not  generally  introduced  into  Europe  until  the  four- 
teenth century,  Woad,  a  somewhat  smiilar  dyestuff,  was  used  in  its  place, 
and  when  Indigo  was  imported  in  large  quantities  through  trade  with 
India,  it  had  to  overcome  serious  obstacles  in  its  competition  with  Woad 


Fig.  7.— €loth  Dyer.     (Middle  Ages.) 


for  dyeing  blue.    There  appears  to  have  been  a  kind  of  Woad  syndicate 
in  existence  at  that  time  with  sufficient  political  influence  to  obtain  severe 

*  We  find  a  reference  in  the  historical  records  of  Venice  in  1194  concerning  the 
importation  of  Indigo  and  Brazil-wood  from  India.  This  latter  named  dyestuff  subse- 
quently gave  its  name  to  the  well-known  South  American  country.  Although  Indigo 
was  employed  in  Venice  at  this  time,  it  does  not  seem  to  have  extended  over  the  rest  of 
Europe  when  the  subsequent  decadence  of  Venice  and  its  industries  led  to  the  wide- 
spread dissemination  of  the  art  of  dyeing  over  entire  Europe.  This  was  probablj'  due 
to  a  cessation  more  or  less  of  the  trade  with  India,  which  was  not  reffained  until  the  sea 
route  to  Asia  was  discovered.  -     • 


12  INTRODUCTION 

laws  against  the  use  of  Indigo  in  man^-  of  the  principal  countries,  and  this 
dye  had  to  overcome  tremendous  opposition  before  it  finally  replaced  the 
much  inferior  Woad.* 

The  discovery  of  America  gave  a  great  impetus  to  the  art  of  dyeing, 
by  making  a  large  number  of  new  coloring  matters  available  for  use. 
Logwood,  and  the  various  red  woods  of  Central  and  South  America  were 
introduced,  and  were  soon  extensively  employed;!  Fustic  was  also  an 
American  product,  and  so  was  cochineal.  All  of  these  new  materials  were 
exceedingly  valuable  additions  to  the  dyestuffs  employed  at  that  time, 
and  soon  came  into  extensive  use.  The  Netherlands  and  Belgium  became 
the  great  centers  of  wool  dyeing,  a  position  which  they  maintained  for 
a  long  period  of  time,  but  the  art  gradually  perfected  itself  in  England 
and  Germany,  as  well  as  in  France.  The  variety  of  vegetable  coloring 
matters  which  were  employed  was  very  numerous,  and  some  were  rather 
peculiar  and  interesting.  In  England,  for  instance,  a  yellow  coloring 
matter  was  extracted  from  onion  skins,  and  was  quite  extensively 
employed. 

Up  to  the  middle  of  the  last  century  dyeing  had  a  rather  gradual  and 
even  development,  though  but  little  attempt  was  made  towards  a  scien- 
tific study  of  the  subject;  but  the  year  1856  brings  us  to  a  period  of  revo- 
lutionary development.  It  was  in  this  year  that  Perkin,  an  English 
student  working  under  Hofmann  in  Germany,  discovered  (during  a 
research  which  had  for  its  object  the  synthesis  of  quinine)  that  the  oxida- 
tion of  aniline  yielded  a  beautiful  violet  coloring  matter  of  great  tinctorial 
power.  This  was  the  beginning  of  the  era  of  artificial  dyestuffs  prepared 
from  the  various  products  of  coal-tar,  and  proved  to  be  an  important 
landmark  in  the  industrial  development  of  chemistry.  Not  only  did 
this  discovery  soon  l)ring  about  a  complete  revolution  in  the  methods  of 
dyeing  through  the  preparation  of  numerous  artificial  dyestuffs,  but  it  also 
brought  the  art  of  dyeing  into  a  more  intimate  and  direct  connection 
with  the  science  of  chemistry,  which  was  then  growing  with  rapidity. 

*  A  lawof  the  Diet  of  1577  prohibited  the  use  of  Indigo  in  Germany,  it  being  described 
as  a  "pernicious  and  corrosive  dye."  The  first  mention  of  Indigo  in  England  is  in  the 
year  1581,  in  c()nne(;tion  with  black  dyeing,  but  it  does  not  seem  to  have  been  used  for 
dyeing  blues.  In  a  document  of  1243  reference  is  made  to  the  duties  payable  on  Woad, 
and  in  12G8  an  agreomoiit  was  recorded  between  the  citizens  of  Norwich  and  the  Woad 
merchants  of  Amicus,  in  France.  Coventry  was  famous  for  its  blue-dyed  woolen  cloths 
as  early  as  1415,  the  color  being  known  as  "Coventry  true  blue."  The  first  guild  of 
dyers  is  mentioned  in  1188,  but  the  first  charter  of  incorporation  was  granted  to  the 
Worshipful  Company  of  Dyers  in  1471. 

t  Even  Logwood  appears  to  have  aroused  considerable  opposition  when  first  employed, 
as  we  find  an  edict  of  (Jueen  Elizabeth  prohibiting  the  use  of  Logwood,  and  directing 
that  all  of  this  material  found  should  be  burnt.  James  I,  in  1620,  prohibited  the 
import  of  Logwood,  but  dyers  apparently  employed  it  under  other  names. 


DISCOVERY  OF  COAL-TAR  COLORS  13 

Previous  to  that  time  the  methods  of  dyeing  were  eminently  unscien- 
tific, crude,  and  more  or  less  surrounded  with  mystery  and  supposed 
secrecy  of  skill.  The  chemist  had  been  too  intently  occupied  in  other 
fields  to  become  interested  in  the  working  out  of  the  scientific  principles 
of  dyeing,  and  only  a  very  few  scientists  had  engaged  themselves  in  its 
investigation.  But  the  discovery  of  the  coal-tar  colors  opened  up  a  wide 
and  most  lucrative  field  for  chemical  research,  and  this  soon  led  to  a  close 
association  of  dyeing  and  chemistry  to  the  mutual  benefit  of  both  sub- 
jects. From  the  dyestuffs  themselves,  the  chemist  was  led  to  an 
investigation  of  the  processes  and  methods  of  dyeing,  and  a  chemical 
study  of  the  fibers  and  mordants,  and  the  action  of  the  various  drugs 
employed.  The  result  was  that  order  and  system  and  knowledge  of  under- 
lying principles  in  dyeing  were  soon  introduced,  where  before  everything 
had  been  more  or  less  obscure  and  chaotic  and  dependent  upon  rule  of 
thumb  methods.  From  that  time  on,  dyeing  became  incorporated  in 
the  general  science  of  chemistry,  and  has  since  drawn  its  sustenance 
from  and  reached  its  highest  development  under  the  guidance  of  that 
comprehensive  parent  of  so  many  industries.  The  old,  crude  methods 
of  dyeing  have  been  relegated  more  or  less  to  the  mysteries  of  antiquity, 
and  have  given  way  to  concise,  clearly  understood,  and  scientific  processes. 
The  majority  of  vegetable  coloring  matters,  whose  use  necessitated  usually 
cumbersome  and  lengthy  methods  of  application,  have  been  replaced 
almost  exclusively  by  the  various  coal-tar  colors,  which  are  easily  and 
quickly  applied. 

The  colors  obtainable  with  the  old  dyes  were  also  subject  to  many 
limitations;  brilliancy  of  hue  in  many  instances  was  impossible,  and  the 
range  of  shades  ordinarily  obtained  was  rather  narrow,  and  not  capable 
of  much  extension  without  seriously  complicating  the  dyeing  process. 
The  introduction  of  the  coal-tar  dyes  made  it  possible  to  obtain  colors 
which  had  hitherto  been  the  despair  of  the  dyer;  and  the  latter  has 
now  at  his  command  the  most  varied  shades,  and  the  most  delicate  and 
brilliant  hues.  But  very  few  of  the  natural  dyes  have  left  even  a 
vestige  of  their  former  selves  in  trade;  some  still  retain  their  prestige  on 
account  of  their  good  qualities  and  cheapness.  Indigo  has  heretofore 
been  the  principal  dyestuff  of  trade,  and  was  a  natural  vegetable  product 
which  withstood  all  the  competition  of  artificial  substitutes;  but  the 
last  few  decades  have  seen  the  successful  synthesis  of  this  very  dye- 
stuff  from  coal-tar  products,  and  it  will  only  be  a  question  of  time  before 
the  vegetable  dye  will  be  driven  entirely  from  the  market.  A  similar 
result  was  witnessed  in  the  case  of  Madder,  which  formerly  ranked  almost 
equal  to  Indigo  in  commercial  importance;  it  was  prepared  by  chemical 
means  from  coal-tar  under  the  name  of  Alizarine,  and  soon  displaced  the 
natural  dyestuff  entirely.     Logwood  still  retains  its  importance  among 


14  INTRODUCTION 

dyestuffs,  principally  on  account  of  the  good,  cheap  blacks  which  can 
be  obtained  with  it.  It  is  surpassed,  however,  in  fastness  by  several  of 
the  coal-tar  blacks,  and  for  many  puiposes  has  been  replaced  by  these 
colors.  Cochineal  is  still  used  to  some  extent  for  the  dyeing  of  scarlets 
and  reds,  but  its  use  is  fast  decreasing,  giving  way  to  the  various  coaV 
tar  red  dyes,  many  of  which  surpass  it  in  fastness.  Fustic  is  employed 
somewhat  at  the  present  time,  but  chiefly  in  combination  with  Logwood 
for  the  production  of  blacks.  It  is  rarely  used  as  a  self-color  for  dyeing 
yellow,  for  many  of  the  coal-tar  colors  surpass  it  in  purity  and  brilliancy 
of  hue,  as  well  as  in  permanence  of  color. 

3.  Dyes  of  Antiquity  Compared  with  Modem  Dyes. — At  this  point 
it  is  of  interest  to  discuss  briefly  the  comparative  permanence  and  color 
values  of  the  old  natural  dyes*  and  the  more  recent  coal-tar  dyes;  for 
much  is  said  (especially  by  those  more  or  less  unacquainted  with  the  prop- 
erties of  dyestuffs)  of  a  derogatory  nature  concerning  the  modern  colors, 
while  the  fastness  of  the  old  dyes  is  highly  extolled.  If  we  examine  in 
review  the  former  vegetable  dyes  we  will  find  that  perhaps  the  fastest 
one  of  all  is  Indigo  (used  for  obtaining  blue  shades  and  for  mixed  shades 
containing  blue) ;  as  this  identical  dyestuff  is  now  prepared  from  coal- 
tar,  we  need  not  proceed  further  with  the  comparison  in  regard  to  it.  There 
are  also  other  blue  Ciyestuffs  of  artificial  origin  which  are  eminently  fast 
and  more  easily  apphed  than  Indigo  (AUzarine  Blues,  etc.),  and  though 
recently  introduced,  vat  colors  are  even  much  faster  than  Indigo.  Red 
was  formerly  dyed  almost  exclusively  (where  fast  colors  were  in  question) 
with  Madder  on  previously  mordanted  wool;  as  the  coloring  principle 
of  Madder  is  made  at  the  present  time  from  a  derivative  of  coal-tar,  and 
is  identical  in  every  respect  with  that  occurring  naturally  in  the  vegetable 
dyestuff,  we  have  at  our  command  the  same  conditions  of  fastness  as 
the  people  of  antiquity ;  we  have  also  far  extended  our  range  of  fast  colors 
in  this  respect  by  the  preparation  of  blue,  yellow,  brown,  green,  and  black 
dyestuffs  belonging  to  the  same  class  as  Ahzariue  Red  (Madder)  and  pos- 

*  In  the  sixteenth,  seventeenth,  and  eighteenth  centuries  the  dyes  that  were  prin- 
cipally employed  for  the  production  of  fast  colors  were  as  follows: 

1.  Blue — Indigo  and  Woad. 

2.  Scarlet  red — Cochineal  and  Kermes. 

3.  Crimson  red — Madder. 

4.  Brown — Walnut  husks. 

5.  Yellow— Weld. 

6.  Black — Iron  tannate  on  Indigo  bottom,  v. 

Many  other  vegetable  dyes  were  used  for  the  production  of  colors,  but  these  were 
known  as  "false"  colors  and  were  not  fast.  In  the  eighteenth  century  the  practice  of 
dyeing  was  regulated  by  very  strict  rules  under  the  "Regulations"  of  Colbert,  and  a 
dyer  was  not  allowed  to  dye  "true"  colors  with  any  of  the  "false"  dyes.  This  close 
government  regulation  had  the  beneficial  effect  of  bringing  into  use  the  best  and  fastest 
colors  available,  as  the  dyer  was  not  allowed  to  misrepresent  his  goods. 


DYESTUFFS  OF  ANTIQUITY  15 

sessing  similar  dyeing  qualities.  Weld  and  Persian  Berries  ajppear  to 
have  been  the  fastest  yellow  dyes  possessed  by  the  ancient  dyers,  and  these 
do  not  compare  to  our  Alizarine  Yellow  (and  some  other  coal-tar  yellows) 
in  respect  to  fastness  and  clearness  of  shade.  The  other  yellow  dyewoods 
which  were  extensively  used  were  all  rather  fugitive,  which  accounts  for 
the  fact  that  most  of  the  solid  yellows  in  the  old  fabrics  are  found  to  be 
much  faded,  and  also  the  compound  shades  of  which  yellow  was  a  com- 
ponent exhibit  a  faded  appearance.  Dull  russet  yellow  and  orange  shades 
were  sometimes  obtained  by  the  Uvse  of  a  metallic  pigment,  and  these, 
of  course,  being  mineral  bodies,  were  extremely  fast,  but  they  lacked  bril- 
liancy and  clearness  of  tone.  This  color  was  obtained  by  steeping  the 
material  to  be  dyed  in  iron  liquor,  prepared  by  dissolving  iron  filings 
in  vinegar  (acetate  of  iron),  and  then  drying  in  the  sun.  Green  colors 
were  obtained  by  the  use  of  the  mineral  pigment  verdigris;  there  do  not 
appear  to  be  any  green  vegetable  dyes  of  importance,  though  it  is 
said  the  Chinese  were  acquainted  with  a  green  dyewood  called  Lo-kao 
which  possessed  great  beauty  and  fastness.  It  was  probably  derived 
from  the  leaves  of  certain  species  of  Rliamnus;  it  was,  however,  exclu- 
sively employed  in  Cliina  and  was  unknown  outside  of  that  country. 
Green  colors  in  modern  methods  of  dyeing,  where  fastness  is  desired,  are 
obtained  by  compounding  fast  yellow  and  blue  dyestuffs  to  the  desired 
shade  of  green.  Black  v/as  formerly  dyed  by  two  methods.  The  first 
employed  Logwood  or  a  similar  dyewood  capable  of  yielding  a  black  color 
on  mordanted  wool,  in  which  case  the  black  was  not  extremely  fast,  espe- 
cially to  light  and  exposure;  we  still  employ  Logwood  for  dyeing  cheap 
blacks  on  wool,  but  we  have  many  other  coal-tar  colors  which  possess 
superior  fastness.  In  the  second  case,  black  was  dyed  by  forming  a 
heavy  deposit  of  tannate  of  iron  in  the  fiber.  A  decoction  of  iron  filings 
and  oak  bark  was  made  with  water  and  this  was  spread  over  the  cloth 
to  be  dyed,  which  was  then  rolled  up  and  allowed  to  remain  for  about  a 
month;  by  that  time  the  iron  rust  had  permeated  the  cloth,  and  it  was 
then  dyed  black  by  steeping  in  a  decoction  of  gallnuts.  This  was  a  rather 
crude  and  lengthy  process,  to  say  the  least,  and  not  at  all  adapted  for 
modern  times.  Brown  shades  were  usually  obtained  by  steeping  the 
cloth  in  a  decoction  of  walnut  husks  and  lime  water.* 

*  A  valuable  source  of  information  concerning  the  dyeing  processes  of  antiquity 
is  a  book  published  in  Venice  in  1548  by  Phchto.  This  person  was  an  officer  in  the 
Venetian  army  and  his  real  name  was  Giovanni  Ventura  Rossetti.  It  was  one  of  the 
first  books  of  its  kind  ever  published,  and  contains  numerous  recipes  and  processes  for 
dyeing  which  the  author  had  personally  collected  in  his  extensive  travels  through 
Europe  and  the  Levant.  A  German  book  on  dyeing  had  already  appeared  at  Strass- 
burg  in  1514,  and  contained  a  description  of  various  dyeing  processes  used  in  Germany 
at  that  time.  From  the  descriptions  given  in  this  book  it  appears  that  a  mordant  of 
aiiun  was  the  basis  of  nearly  all  the  colors  dyed  in  Germany.     The  first  book  dealing 


16  INTRODUCTION 

At  the  present  lime  the  great  demand  placed  on  the  dyer  is  cheap- 
ness and  volume  of  i)roduction,  which  must  often  be  attained  at  a  con- 
siderable sacrifice  of  fastness  of  color.  If  time  and  expense  were  not  so 
carefully  economized,  there  is  no  reason  why  the  modern  dyer  (if  he  be 
well  acquainted  with  the  principles  of  his  profession)  should  not  turn  out 
colors  of  equal  fastness,  if  not  superior  in  many  cases,  to  the  colors  of 
antiquity,  and  the  range  of  shades  at  his  command  would  be  far  more 
extensive.  We  must  bear  in  mind  that  the  old  dyeing  processes  were  usually 
long  and  tedious  methotls,  and  time  was  httle  or  no  factor  in  the  operation. 
If  greater  brilliancy  of  hue  is  desired,  as  is  frequently  the  case  in  modern 
times,  it  is  obtainable  only  by  the  use  of  certain  colors,  the  majority  of 
which  are  not  characterized  by  any  special  degree  of  fastness.  These 
modern  dyes  far  surpass  the  old  ones  in  this  quahty  of  brilhancy  and 
purity  of  tone,  but  if  such  quality  is  demanded,  a  high  degree  of  fast- 
ness must  at  the  same  time  be  sacrificed. 

4.  Apparatus  and  Equipment  for  Dye-Testing. — In  cari-j-ing  out  the 
dye-tests  to  be  described  in  this  book,  it  will  be  found  convenient  to 
employ  skems  of  wool  and  silk  weighing  5  grams  and  of  cotton  10 
grams.  The  dyebatlis  should  conveniently  contain  about  300  to  400  cc. 
of  water,  and  should  be  of  porcelain,  glass,  or  enameled  iron-ware.  A 
good  form  of  experhnental  dyebath  is  that  shown  in  the  illustration 
(Fig.  8).  It  consists  of  a  round  copper  or  sheet-iron  vessel  lined  inside 
with  asbestos,  and  provided  with  a  perforated  iron  bottom  and  top.  Its 
top  contains  four  openings  through  which  the  dyepots  are  inserted.  This 
airbath  is  placed  on  an  iron  stand  prov-ided  with  a  gas  burner.  The  dye- 
pots  are  porcelain  and  are  held  by  beveled  copper  collars  wdth  wooden 
handles.  The  airbath  is  so  arranged  that  when  the  dyepots  are  in  posi- 
tion they  are  raised  about  an  inch  above  the  bottom  plate.  Such  a  dye- 
bath  allows  of  a  uniform  heating  of  the  four  pots,  and  the  temperature 
may  be  raised  rapidly  or  slowly  at  will,  by  regulation  of  the  gas  flames, 
and  it  is  an  eas}'  matter  to  bring  the  liquid  in  the  pots  to  an  active  boil. 

Instead  of  using  a  gas  burner  to  supply  the  heat,  it  will  be  found  con- 
venient, where  electricity  is  available,  to  employ  a  round  electric  stove 
plate,  in  which  case  the  bodj'  of  the  airbath  may  be  placed  directly  on 
the  electric  stove,  and  the  perforated  bottom  may  be  dispensed  with. 
This  method  of  heating  gives  a  verj^  uniform  temperature  in  all  four  dye- 
pots, and  as  the  heat  is  easily  regulated  it  may  be  maintained  at  a  con- 
stant point,  and  so  avoid  overheating  of  the  dyepots. 

There  are  other  forms  of  experimental  dyebaths  in  use  where  solu- 
tions of  calcium  chloride,  common  salt,  glycerin,  etc.,  are  used  for  heating 
the  dyepots.     Strong  solutions  of  calcium  chloride  are  capable  of  being 

with  the  subject  of  dyeing  printed  in  English  appeared  in  London  in  1583,  and  was  a 
translation. 


EXPERIMENTAL  DYEBATHS 


17 


m 


heated  far  above  the  boihng-point  of  water,  and  consequently  in  such 
a  bath  it  is  easy  to  bring  the  dyepots  to  the  boil.  But  calcium  chloride 
solutions  attack  the  baths  in  which  they  are  contained.  In  case  of  cop- 
per vessels  with  soldered 
seams  the  solder  is  rapidly 
eaten  out  and  leaks  fre- 
quently occur.  In  a  dye- 
bath  using  a  solution  of 
calcium  chloride  the  seams 
should  be  brazed,  which 
makes  the  apparatus  rather 
expensive,  and  even  then 
the  copper  itself  is  soon 
attacked. 

In  large  dye  laboratories 
to  be  met  with  in  dyestuff 
factories  or  dyehouses  and 
mills,  and  where  a  dyebath 
is  required  to  take  care  of 
a  large  number  of  dyepots 
at  once,  a  good  form  of 
apparatus  is  a  cast-iron  or 
wooden  trough  1  to  lb  ft. 
wide,  3  to  4  ft.  long  and  about  10  ins.  deep.  This  is  hned  with  a  good 
quality  of  sheet  lead.  The  top  consists  of  sheet  lead  properly  braced,  and 
containing  openings  for  the  dyepots.     In  this  form  of  bath  several  dozen 

steam  Outlet  P^*^  "^^^  ^^  heated  at  once, 

.steam  _L  The  solution  used  in    the 

Q  bath    should    be     calcium 

-^  chloride    of   such   strength 

that  a  temperature  of  220° 

F.  may  be  obtained.     This 

will  be  sufficient   to  allow 

of  the  dyebaths  in  the  pots 

to  be  brought   to  the  boil. 

The  heating  of  the  bath  is 

effected   by  a   lead   steam 

coil.      With    solutions     of 

common  salt  it  is  difficult 

to  obtain    a    temperature 

of  212°  F.  in  the  dyepots;  that  is,  to  bring  them  to  a  state  of  active 

boiling.      A    temperature    of    210°    F.,    however,    can    be    maintained, 

and    probably    this    is    nearer    the    actual    temperature    of   the    open 


Fig.  8.— Dye-Test  Bath;  Gas  Heated. 


i  steam 


Fig.  9.— Dye-Test  Bath;  Steam  Heated. 


18  INTRODUCTION 

dyevat  in  practice,  and  gives  as  good  results  as  if  the  liquid  was  in 
an  actual  state  of  ebullition.  Solutions  of  common  salt  are  perhaps  to 
be  preferred  to  those  of  calcium  chloride  where  a  copper  dyebath  is  used, 
as  they  do  not  have  a  corroding  action.  By  the  use  of  glj^cerin  in  the  bath 
a  boiling  temperature  can  readily  be  obtained  in  the  dyepots,  but  glycerin 
baths  continually  emit  disagreeable  vapors.  Whenever  possible,  baths 
containing  such  solutions  should  be  heated  by  a  steam-coil  (with  steam 
under  pressure)  rather  than  by  direct  gas  flames.  The  great  disadvan- 
tage of  all  baths  using  solutions,  and  one  from  which  the  airbath  is  free, 
is  that  the  water  is  constantly  being  evaporated  from  the  solution  and 
has  to  be  as  constantly  replaced. 

When  dyeing  the  test  skeins  they  should  be  systematically  "  worked  " 
or  turned  in  the  dye  solution.  This  is  best  accomplished  by  suspending 
the  skein  in  the  bath  from  two  glass  rods,  and  using  these  from  time  to 
time  for  the  purpose  of  turning  the  skeins.  These  glass  rods  should  be 
J  to  f  in.  in  diameter,  and  8  to  10  ins.  in  length.  The  skeins  should  be 
turned  sufficiently  to  insure  even  penetration  of  the  solution  through  the 
entire  portion  of  the  material. 

The  dye  solution  employed  in  the  baths  will  usually  cause  discolor- 
ations  on  the  porcelain  or  glass  beakers  used,  as  well  as  on  the  glass  rods 
and  other  vessels  with  which  they  come  in  contact.  In  starting  a  new 
dye-test  it  is  essential  that  all  of  the  apparatus  be  clean  and  free  from  pre- 
vious dye  stains.  As  many  of  these  stains  cannot  be  removed  readily  by 
water  or  soap  solutions,  stronger  chemical  treatment  is  generally  necessary. 
For  this  purpose,  it  is  well  to  have  on  hand  a  strong  solution  of  chromic 
and  sulphuric  acid.  This  is  prepared  by  using  about  1  part  of  sohd  sodium 
bichromate  with  10  parts  of  strong  sulphuric  acid  (sp.  gr.  1.84).  This 
mixture  should  be  kept  in  a  stout  glass  or  porcelain  container.  It  will 
remove  almost  all  color  stains  on  apparatus  and  can  be  used  over  and 
over  again  if  care  is  taken  not  to  dilute  it  unduly.  As  the  solution  is  very 
corrosive  it  should  not  get  on  the  hands  or  clothing  or  on  metal  ware. 

The  skeins  of  yarn  for  use  in  the  test  experiments  may  conveniently 
be  made  on  a  small  yarn  reel,  such  as  is  used  in  most  yarn  mills  for  making 
test  skeins  to  determine  the  size  of  the  yarn  (see  Fig.  10).  In  the  case  of 
wool  and  silk  yarns  the  material  will  generally  be  obtained  in  the  form 
of  large  hanks  or  skeins.  These  will  have  to  be  put  on  a  suitably  sized 
"swift"  (or  frame  for  holding  the  skein)  and  run  therefrom  to  the  reel- 
ing machine.  In  the  case  of  cotton,  this  can  usually  be  obtained  in  the 
form  of  cones,  which  are  far  more  convenient  to  reel  from.  There  is  wide 
variation  possible  in  the  selection  of  the  yarn  to  be  used.  It  is  well  not 
to  use  too  fine  a  yarn,  as  this  consumes  considerable  time  in  the  prepa- 
ration of  the  test  skeins;  also  finer  yarns  are  more  expensive  than 
coarser  ones,  and  are  more  Uable  to  break  and  tangle  up.     In  the  case. 


MATERIALS    FOR   DYE-TESTS 


19 


of  wool  dyeing,  two-ply,  soft  worsted  yarns  will  yield  better  looking 
tests  than  carded  woolen  yarns.  With  silk  it  is  best  to  have  twisted 
thread  silk  yarns,  as  these  will  break  and  tangle  less  and  may  be  easily 


Fig.  10.     Yarn  Reel. 

rewound  if  required.  If  this  form  of  silk  yarn  is  too  expensive,  however, 
spun  silk  yarn  may  be  used.  With  cotton  it  is  well  to  use  a  good 
quaUty  two-ply  combed  peeler  yarn    (in  size  about  2/20's  or  2/ 16's). 


^^fifduaMaa^irm 


Fig.  11. — Porcelain  Dyepots. 


As  already  mentioned,  the  wool  and  silk  should  be  made  up  into  skems 
weighing  5  grams,  while  the  cotton  is  used  in  skeins  of  10  grams. 

The  dyestuffs  and  various  chemicals  employed  in  carrying  out  the 
dye-tests  should  be  used  in  the  form  of  solutions  of  such  strength  that 


20 


INTRODUCTION 


C  ; 

20°  c; 

10      50 


small  quantities  of  the  products  may  be  measured  out  in  convenient  vol- 
umes. As  the  amount  of  material  being  dyed  (5  or  10  grams)  is  relatively 
small,  and  as  small  amounts  of  the  dycstuffs,  etc.,  are  used,  it  would  be 
both  inconvenient  and  inaccurate  (unless  very  precise  weighings  were 
made  on  expensive  and  accurate  balances)  to  weigh  the  chemicals  em- 
ployed in  each  test;   but  by  preparing  solutions  of  definite  strengths  the 

required  amounts  may  be  readily  and  accu- 
rately measured  off.  The  proper  preparation 
of  these  solutions  will  be  taken  up  as  demanded 
by  the  course  of  the  experiments.  For  the 
measurement  of  the  solutions  a  glass  cylinder 
graduated  into  100  cc.  is  very  convenient;  this 
readily  permits  of  the  rather  accurate  meas- 
urement of  such  quantities  as  5  cc,  10  cc, 
etc.  Volumetric  measuring  flasks  of  100,  500, 
and  1000  cc.  capacity  are  also  convenient  for 
the  preparation  of  standard  solutions  of  dye- 
stuffs  and  chemicals.  In  cases  where  very 
minute  quantities  are  desired,  and  it  is  neces- 
sary to  measure  to  an  accuracy  of  iV  cc,  a 
small  glass  tube  (known  as  Mohr's  pipette) 
accurately  graduated  to  iV  cc.  is  very  useful. 
These  pipettes  may  be  obtained  in  sizes  holding 
5,  10,  25,  or  50  cc,  and  by  their  use  volumes  accurate  to  iV  cc.  may  be 
readily  measured  out.  A  thermometer  is  also  necessary  for  use  in  the 
dye-tests.  A  good,  practical  and  inexpensive  form  is  the  so-called 
"dairy"  thermometer  with  a  paper  scale  and  reading  to  220°  F.  By 
the  use  of  this  thermometer  the  temperatures  of  the  dye  solutions  or 
other  liquids  employed  in  the  tests  may  be  ascertained.     An  agate  cup 


Fig.  12.— Glass  Cylinder  and 
Graduate. 


af'PBfMM,!!!!!!'™"^"""''",""!!"!!! 


Fig.     13.— Mohr's  Pipette. 


(pint  or  quart  size)  is  a  useful  adjunct  for  the  preparation  and  mixing 
of  the  various  solutions  needed.  A  bunch  of  small  tags  should  also  be 
available  so  that  every  skein  with  which  a  test  has  been  made  may  be 
properly  labeled  for  indentification  and  reference. 

5.  Practical  Process  of  Dyeing. — In  carrying  out  the  methods  of 
dyeing  on  a  practical  scale,  the  object  is  usually  to  impregnate  the  material 
to  be  dyed  with  the  various  solutions  of  coloring  matter  or  other  materials 


VATS  FOR  DYEING   YARN 


21 


Waste  Pipe 


Fig.  14. — Dyevat  for  Yarn.     (Direct  Steam.) 


s        ^^ 


:^E 


'i  v  A  I.. A  v:.i  u'A  \:-A  v.'A  w/A  ^^-:'^  XWA\  v/M\Y^\  v,fA\  YVA  v^-f-'i  m,^ 


T)       O        O 


sL 


m: 


^^ 


Fig.  15. — Dyevat  for  Yarn.     (Indirect  Steam.) 


22 


INTRODUCTION 


which  may  be  employed.     There  are  two  general  methods  of  procedure 
for  this  purpose: 

(1)  The  textile  material  is  simply  immersed  in  the  dye  liquor,  and  moved 
about  or  "  worked "'  in  such  a  manner  as  to  promote  an  even  distribution  of 
the  color.  The  form  of  the  material  being  dyed  will,  of  course,  necessitate 
modifications  in  the  method  of  handling.  In  the  case  of  loose  wool  or 
cotton,  the  material  is  immersed  in  a  suitable  vat  or  tank  containing  the 
dye  liquor,  and  is  stirred  about  from  time  to  time  by  means  of  poles.  When 


Fig.  16.— Winch  for  Dyeing  Cloth. 


yarn  is  to  be  dyed,  the  skeins  are  placed  on  sticks  and  hung  in  the  dye 
liquor  conttiined  in  a  tank  of  suitable  dimensions  and  usually  of  rectangu- 
lar form,  the  sides  of  the  tank  supporting  the  dj'e  sticks.  The  position 
of  the  hanging  skeins  is  changed  from  time  to  time  by  turning  so  that 
every  part  will  be  equally  expo.:en  to  the  action  of  the  dN'e  liquor.  In 
the  case  of  cloth  (or  woven  fabrics  in  general),  the  ends  are  joined  together, 
thus  forming  an  endless  string  which  is  run  continuously  through  the  dye 
liquor  over  a  rotating  "winch."  Of  cotirse  various  mechanical  devices 
have  been  introduced  for  the  purpose  of  economizing  labor  and  for  auto- 


VATS   FOR  DYEING  LOOSE  STOCK 


23 


Fig.  17.— Hand  Vat  for  Dyeing  Loose  Stock.     (Both  Direct  and  Indirect  Steam.) 


Fig.  18. — Round  Wooden  Dyevat,  Vertical  Section. 


24 


INTRODUCTION 


matically  movinp;  the  material  with  a  minimum  amount  of  injury  to  the 
fiber.  Although  a  considerable  quantity  of  loose  wool  and  cotton  is  still 
dyed  in  the  primitive  fashion  by  hand  poling,  the  more  approved  method 
is  to  employ  macliines  for  stock-dyeing.  These  usually  consist  of  a 
large  basket  divided  into  several  interior  compartments.  The  stock  is 
loaded  into  the  basket  which  is  then  made  to  rotate  in  the  dye  liquor  con- 
tained in  an  outer  tank  into  which  the  basket  fits.  Yarn  may  be  dyed 
by  placing  it  on  sticks  held  in  a  revolving  frame  which  moves  slowly 
through  the  dye  liquor.     Cloth  may  be  automatically  run  through  the 


3 


Fig.  19. — Series  of  Vats  for  Dyeing  Loose  Stock. 


dye  liquor  in  string  form  by  means  of  moving  rollers,  or  it  may  be  moved 
back  and  forth  in  open  width  by  passing  from  one  roll  to  another  (as  in 
the  jigger). 

(2)  The  material  to  be  dyed  may  be  held  stationary  in  a  compact 
form  and  the  dye  Uquor  is  circulated  through  it  by  means  of  pumps  or 
steam  or  air  pressure.  Machines  of  this  type  are  coming  into  vogue 
very  largely  at  the  present  time,  as  they  possess  the  advantage  of  being 
able  to  handle  large  quantities  of  material  in  a  small  space,  and  further- 
more they  do  not  injure  the  goods  by  the  mechanical  straining  and  fric- 


DYEING   MACHINES 


25 


tion  necessitated  in  the  older  methods.     Large  economies  in  dyestuflf, 
steam,  and  water  are  also  possible. 


Fig.  20.— Showing  General  Principle  of 
Pack  System  of  Dyeing. 


Fig.  21. — The  Dreze  Dyeing  Machine. 
(Showing  Pack  System.) 


Fig.  22.— Revolving  Cylinder  Type  Raw  Stock  Dyeing  and  Bleaching  Machine. 
(Delahunty  Dyeing  Machine  Co.) 

The  construction  and  methods  of  operations  of  the  various  types  of 
dyeing  machines  will  be  taken  up  in  detail  in  their  proper  connection. 

The  practical  operation  of  dyeing  usually  necessitates  several  con- 
secutive processes,  as  follows: 


26 


INTRODUCTION 


(1)  Scouring  (or  wet  ting-out); 

(2)  Dyeing  (which  may  also  include  a  mordanting  operation); 

(3)  Rinsing; 

(4)  Hydro-extraction  (or  removal  of  the  excess  of  water  by  squeez- 

ing, centrifugal  action,  or  wringing); 

(5)  Drying. 

The  exact  nature  of  these  processes  and  the  appliances  employed  m 
carrying  them  out  will  depend  very  largely  on  the  character  and  form 
of  the  material  being  dyed. 


Fig.  23.— Hydro-Extractor.     (Tolhurst.) 


6.  Water  and  Steam  in  the  Dyehouse. — As  water  is  used  in  rela- 
tively large  quantities  in  nearly  all  the  operations  of  dyeing,  it  becomes 
an  essential  feature  to  be  considered  carefully  in  the  practical  dyehouse. 
It  is  not  only  necessary  that  water  be  available  in  large  quantities  and 
at  a  low  cost,  but  also  that  it  be  comparatively  pure  in  quality,  of  a  low 
degree  of  hardness,  and  contain  a  minimum  amount  of  iron.  Owing  to 
the  importance  of  the  water  in  dyeing,  it  will  receive  a  special  consider- 
ation in  the  course  of  this  work. 

The  amount  of  water  required  in  dj'eing  operations  depends  both 
on  the  nature  and  character  of   the  fiber  as  well  as  the  construction 


WATER  IN  DYEING 


27 


and  form  of  the  machine  in  which  the  dyeing  takes  place.  When  the 
material  is  dyed  in  the  open — that  is  to  say,  not  packed  tightly  in  the 
machine,  but  where  the  goods  are  required  to  be  worked  in  the  solution — 
there  will  be  required  a  sufficient  volume  of  water  to  properly  manipu- 
late  the  goods.  Cotton  takes  less  water  than  wool  or  silk,  being  a  more 
compact  fiber  and  yielding  denser  yarns  and  woven  goods.  It  requires 
about  twenty  times  its  weight  of  water  for  the  dyebath;  that  is  to  say,  1  lb. 


Fig.  24. — Yarn  and  Slubbing  Dyeing  Machine.     (Lorimer  Machinery  Co.) 


of  cotton  yarn,  for  example,  will  require  about  2|  gallons  of  dye  Hquor 
in  which  to  dye  it,  and  a  vat  for  dyeing  100  lbs.  of  cotton  is  usually  figured 
so  as  to  contain  225  to  250  gallons  of  liquor.  Wool  and  silk  will  require 
about  twice  the  proportion  of  dyebath  as  cotton ;  that  is  to  say,  1 :  40  or 
1:  50,  or  1  lb.  of  wool  (or  silk)  in  skein  yarn  form  will  require  about  5  gal- 
lons of  dye  liquor;  less  than  this  will  be  found  impracticable,  as  it  will 
not  be  possible  to  work  the  material  satisfactorily  in  order  to  obtain  uni- 
form penetration.  Where  dyeing  machines  are  used  of  such  a  character 
that  only  a  portion  of  the  material  is  in  the  dye  liquor  at  any  one  time, 


28 


INTRODUCTION 


or  where  the  material  is  tip;htly  packed  and  the  dye  Uquor  is  circulated 
through  it,  a  much  smaller  proportion  of  liquor  will  be  needed  than  that 
mentioned  above.  Under  these  conditions  the  relative  proportions  of 
water  and  fiber  may  drop  down  to  as  low  as  1:15  or  even  1:10. 

For  purposes  of  rinsing  after  dyeing  it  will  require  at  least  as  much 
water  as  originally  employed  for  dyeing,  the  purpose  being  to  replace 
the  residual  dye  liquors  held  in  the  interstices  of  the  yarns  and  fibers 
with  clear  fresh  water  so  as  to  wash  away  the  color  which  would  other- 
wise be  supei-ficially  deposited  on  the  gootls.  In  general  it  may  be  stated 
that  each  pound  of  dyed  yarn  will  require  from  2  to  5  gallons  of  water 
for  proper  rinsing.  Of  course,  there  may  be  cases  where  a  much  more 
thorough  rinsing  is  necessary,  and  in  consequence,  a  greater  proportion 
of  water  will  be  needed. 


Fig.  2.5. — Cop  Dj-eing  Machine. 


As  most  of  the  liquors  cmploj^ed  in  dyeing,  scouring,  etc.,  are  heated 
and  often  require  to  be  raised  to  the  temperature  of  boiling,  it  is  mani- 
fest that  large  quantities  of  steam  are  used  in  the  d3'ehouse.  In  the  old 
days,  dyevats  were  heated  by  direct  fire,  but  at  the  present  time  steam 
heating  is  universally  employed.  Heating  by  steam  may  be  done  either 
by  the  use  of  a  clo.sed  coil  of  pipe,  or  b}'  the  use  of  a  perforated  pipe,  and 
thus  blowing  the  live  steam  directly  into  the  liquor.  The  former  method 
is  preferable,  as  it  does  not  introduce  into  the  dyebath  any  of  the  impurities 
(such  as  oil)  which  may  be  carried  along  bj^  the  steam.  Also  the  dye- 
bath  does  not  become  continually  diluted  by  water  from  the  condensed 
steam.  Another  bad  feature  of  having  live  steam  blowing  directly  mto 
the  bath  is  that  it  causes  excessive  agitation  in  the  hquor  which  may 
result  in  the  tangling  and  felting  of  the  goods,  and  also  the  goods  directly 


STEAM   IN   DYEING 


29 


in  contact  with  the  live  steam  are  in  danger  of  becoming  overheated  and 
injury  to  the  color  or  to  the  fiber  itself  may  result.  Economy  in  the 
use  of  steam  has  an  important  bearing  on  the  actual  cost  of  dyeing.  As 
steam  for  the  dyehouse  is  usually  obtained  in  connection  with  steam  for 
the  power  plant,  it  is  often  possible  to  employ  the  exhaust  steam  from 
the  engine  for  the  purpose  of  heating  the  dyevats.  This,  however,  is 
not  possible  where  a  condenser  type  of  engine  is  used,  though  arrange- 
ment may  be  made  whereby  the  hot  water  from  the  condenser  may  be 
utilized.     Steam  for  heating  dyevats  should  not  be  employed  at  a  very  high 


Fig.  26. — Skein  Dyeing  Machine.     (Giles  JJye  Machinery  Co.) 


pressure  (such  as  employed  for  engines),  but  a  reducing  valve  should  be 
introduced  into  the  steam-main  coming  into  the  dyehouse  so  that  the 
pressure  may  not  be  over  40  lbs. 

The  problem  of  removing  the  dense  vapors  usually  encountered  in 
a  dyehouse  is  an  important  one,  both  on  account  of  the  health  of  the  opera- 
tives, and  for  the  production  of  good  work.  These  vapors  may  be  removed 
either  by  the  use  of  a  suction  fan  or  by  the  natural  ventilation  obtained 
by  a  suitable  arrangement  of  the  dyehouse  roof.  In  cold  weather  satis- 
factory results  in  the  removal  of  fog  cannot  be  obtained  unless  heated 
air  be  introduced  into  the  dyehouse  in  case  suction  fans  are  employed, 


30 


INTRODUCTION 


for  as  the  fan  expels  the  air  from  the  dyehouse,  if  fresh  cold  air  is  drawn 
in  from  the  outside  it  will  help  to  increase  the  fog  by  lowering  the  tempera- 
ture inside.  A  good  plan  is  to  draw  the  entering  air  from  the  heated 
drj'ing  rooms  or  the  boiler  house,  and  this  will  be  found  to  expel  rapidly 
any  fog  produced  in  cold  weather.  In  case  the  dyehouse  is  located  in 
a  separate  building  of  a  single-story  construction,  it  is  possible  to  arrange 


Fig.  27. — Squeezing  Machine  for  Cloth  or  Yarn. 


the  roof  in  such  a  manner  as  to  give  excellent  ventilation  which  will 
effectually  remove  all  fog  in  both  warm  and  cold  weather. 

As  proper  light  has  an  important  bearing  on  the  problems  of  color 
matching,  a  dyehouse  well  lighted  from  a  northern  exposure  would  be  the 
most  suitable.  This,  however,  cannot  always  be  practically  reahzed; 
although  under  the  conditions  prevailing  the  best  light  possible  should  be 
given  the  dyehouse,  and  the  usual  practice  of  placing  this  department  of 
the  mill  in  a  dark  basement  should  be  condemned. 


DYEING   DIFFERENT   FORMS  OF  TEXTILES 


31 


7.  Forms  in  Which  Textiles  are  Dyed. — With  respect  to  the  form  in 
which  textile  materials  are  dyed,  this  varies  greatly  with  the  circum- 
stances of  manufacture.  Wool  is  extensively  dyed  in  the  loose  state,  and 
also  in  the  form  of  slubbing  and  tops.  Yarns  of  both  wool  and  worsted 
are  also  largely  dyed.  In  cases  where  woven  fabrics  are  to  be  finished 
in  solid  colors,  the  dyeing  is  generally  done  in  the  piece.  Cotton  is  also 
largely  dyed  in  the  loose  state,  though  both  yarns  and  piece-goods  are 
extensively  colored.  Silk  is  dyed  chiefly  in  the  form  of  skeins  of  yarn, 
and  to  a  much  less  degree  in  the  piece.  Loose  silk,  of  course,  can  only  be 
dyed  in  the  case  of  waste  silk.     In  the  case  of  both  cotton  and  wool,  it  is 


Fig.  28.— Machine  for  Brushing  and  Lustering  Skein  Yarns. 

cheaper  to  dye  in  the  loose  state  than  in  the  form  of  yarn,  and  there  is 
but  little  trouble  experienced  in  getting  the  resultant  yarn  even  in  color, 
as  the  carding,  drawing,  and  spinning  processes  will  even  up  any  irregu- 
larities which  may  have  been  formed  in  the  dyed  color  of  the  loose  stock. 
The  color  also  has  better  penetration  and  in  some  cases  is  faster.  There  is 
also  a  considerable  saving  in  the  manufacturing  costs,  for  when  yarn  is 
dyed  it  is  necessary  to  reel  the  yarn  from  the  cops  or  bobbins  (on  which  it 
is  spun)  into  the  form  of  skeins;  these  latter  are  then  dyed,  and  must 
again  be  wound  back  into  the  desired  package,  such  as  bobbin  (for  weaving), 
cone,  or  tube.     Whereas,  if  the  material  is  dyed  in  the  loose  stock,  the  cop 


32 


INTRODUCTION 


or  bobbin  obtained  by  spinning  is  used  directly  for  weaving,  or  is  wound 
directly  into  tube  or  cheese,  if  desired  for  other  purposes.  There  are  some 
drawbacks,  however,  to  dyeing  in  the  loose  state.  In  the  first  place,  there 
is  always  more  or  less  of  the  colored  material  left  over  in  the  manufacturing 
in  the  form  of  card  waste,  slubbing,  roving,  etc.,  which  has  a  lower  value, 
as  it  is  much  harder  to  utilize  than  if  the  fiber  were  undyed.     In  the 


Fig.  29.— Yarn  Glazing  and  Softening  Machine. 

second  place,  the  dyed  stock  is  generally  somewhat  more  difficult  to  manu- 
facture and  spin  than  the  undyed,  the  fibers  becoming  more  or  less  matted 
together,  and  lose  considerable  of  their  elasticity  and  good  spinning  qual- 
ities. In  the  case  of  cotton,  most  of  the  natural  wax  on  the  fiber  is  re- 
moved so  that  the  stock  is  difficult  to  card  and  spin.  On  this  account  it  is 
not  always  feasible  to  dye  cotton  in  the  stock,  as  the  fiber  may  be  left  in 
a  condition  impracticable  for  spinning.      Furthermore,  stock  dyeings,  as 


HYDRO-EXTRACTING   DYED   GOODS 


33 


a  rule,  do  not  have  the  brilhancy  or  purity  of  hue,  which  is  obtainable 
in  skein  dyeing,  for  the  manufacturing  processes  through  which  the  stock 
must  pass  deteriorate,  more  or  less,  the  quality  of  the  color.  Dyeing  in 
the  piece  is  of  course  the  cheapest  form  of  handling  textile  materials,  as 
in  this  case  there  is  no  after-waste  of  dyed  material ;  but,  of  course,  piece 
dyeing  is  limited  to  the  production  of  solid  colors — that  is,  a  single  color 
over  the  entire  piece.  There  are,  however,  certain  methods  by  which 
two  color  effects  may  be  obtained,  such  as  using  mixed  fibers  (wool  and 


Fig.  30. — Stretching  and  Glazing  Machine  for  Yarns. 


cotton,  silk  and  cotton,  etc.)  or  by  employing  yarns  especially  treated 
so  as  to  take  a  deeper  color  or  not  to  take  the  color  at  all  (resist  yarns). 
8.  Hydro-extracting  and  Drying. — The  purpose  of  hydro-extracting  (or 
squeezing)  is  to  remove  the  large  amount  of  water  which  is  mechanically 
held  in  the  interstices  of  the  fibers  so  as  to  permit  of  better  and  more  rapid 
drying.  Yarns,  cloth,  etc.,  even  after  thorough  squeezing  will  still  retain 
from  1  to  1^  times  their  weight  of  water.  By  hydro-extracting  in  an 
efficient  form  of  centrifugal  machine  the  proportion  of  water  left  in  the 
goods  is  about  65  to  100  per  cent  of  their  v/eight;  that  is  to  say,  100  lbs. 


34 


INTRODUCTION 


of  dyed  and  rinsed  yarn,  for  instance,  after  being  properly  centrifuged  will 
still  contain  about  65  to  100  lbs.  of  water. 

The  drying  of  dyed  material  is  a  process  which  has  to  be  carried  out 
carefully,  and  in  many  cases  with  proper  respect  to  the  dyestuff  employed. 
The  apparent  color  of  the  material  at  times  alters  considerably  on  drying; 
this  is  especially  true  of  cotton,  which  always  appears  much  darker  in 
color  when  wet.  Nearly  always  some  form  of  artificial  drying  is  resorted 
to,  as  drying  in  the  air  is  generally  inconvenient  and  also  takes  too  long. 


Fig.  31. — Silk  Skein  Stretching  and  Lustering  Machine. 


Generally  suitably  heated  rooms  are  used,  or  machines  specially  constructed 
to  take  care  of  the  material  being  dried.  It  is  never  well  to  dry  at  a  very 
high  temperature,  as  this  will  usually  affect  both  the  fiber  and  the 
coloring  matter,  though  there  is  not  much  chance  of  danger  if  the  tempera- 
ture is  kept  at  180°  F.  or  lower. 

9.  After-treatment  of  Dyed  Material. — It  is  frequently  necessary  after 
dyeing  to  subject  the  dyed  goods  to  further  operations  which  may  properly 
be  considered  as  merely  a  continuation  or  finishing  off  of  the  dyeing  process. 
Woolen  material,  for  example,  is  sometimes  soaped  in  order  to  remove 


METHODS  OF  AFTER-TREATMENT 


35 


excess  of  coloring  matter.  Cotton  dyeings  are  frequently  passed  through 
a  softening  bath  containing  usually  an  oil  emulsified  with  soap  or  alkali. 
A  small  amount  of  oil  is  thus  left  in  the  fiber  which  has  the  effect  o^  softening 
the  goods  as  well  as  of  brightening  the  color.  Many  operations  of  dyeing 
tend  to  make  cotton  harsh  and  stiff,  as  when  mordanting  with  tannin  and 
metallic  salts  or  with  sulphur  dyes.  The  oil  treatment  much  improves 
the  appearance  and  handle  of  the  dyed  goods.  Silk  is  very  often  "  bright- 
ened "  and  "  scrooped  "  after  dyeing;  this  is  usually  accomplished  by 
passing  the  dyed  goods  through  a  bath  containing  acetic  or  tartaric  acid, 


Fig.  32. — Yarn  Stretching  and  Beating  Machine. 


squeezing,  drying,  or  steaming  and  stretching  in  a  special  machine.  The 
effect  of  the  acid  is  to  give  the  fiber  a  crackling  or  crunching  sound  when 
squeezed  in  the  hand,  which  is  the  so-called  "  scroop";  while  the  steaming 
and  stretching  serves  to  straighten  out  the  fiber  and  give  it  a  high  luster. 
In  old  methods  of  dyeing  woolen  goods  the  dyed  color  was  frequently 
"  saddened  "  by  passing  the  goods  through  a  bath  containing  copperas 
(sulphate  of  iron).  The  effect  of  this  was  to  form  an  iron  lake  with  the 
dyestuff  (usually  a  vegetable  mordant  coloring  matter),  which  was  always 
darker  and  duller  than  the  other  lakes,  and  thus  dulled  or  "  saddened  " 
the  color. 


CHAPTER  I 

CHEMICAL  STUDY  OF  THE  FIBERS* 

1.  Action  of  Acids  on  Textile  Fibers. — The  animal  and  vegetable  fibers 
show  a  marked  contrast  in  their  behavior  with  acids.  Wool  absorbs  min- 
eral acids  (sulphuric,  hydrochloric,  and  nitric)  from  solution  and,  unless 
the  acid  is  quite  concentrated,  the  fiber  is  not  decomposed.  The  acid,  in 
this  case  no  doubt  combines  chemically  with  the  wool  on  account  of  the 
iasic  nature  of  this  fiber^  This  is  evidenced  by  the  fact  that  wool  which 
has  been  treated  with  acid  \/ill  dye  with  acid  coloring  matters  much 
better  than  ordinary  wool.  Also,  when  wool  is  treated  with  a  solution 
containing  sulphuric  acid  and  then  washed  until  the  wash  waters  are 
neutral,  there  will  still  be  some  of  the  acid  remaining  in  the  wool. 
Nitric  acid,  unless  very  dilute,  gives  wool  a  yellow  color,  especially  if  the 
acid  is  heated.  Below  a  strength  of  5°  Tw.,  however,  the  yellow  color  is 
formed  very  slowly,  and  therefore  nitric  acid  of  this  strength  may  be  used 
for  stripping  many  dyed  colors  from  woolen  rags  and  shoddy.  Cotton,  on 
the  other  hand,  is  rather  easily  affected  by  solutions  of  the  mineral  acids, 
especially  when  such  a  solution  is  allowed  to  dry  into  the  fiber.  Cotton 
does  not  possess  any  basic  qualities,  and  therefore  does  not  combine 
chemica'-ly  with  the  acid,  thereby  neutralizing  it,  as  in  the  case  of  wool. 
Unless  employed  in  very  weak  solutions,  all  the  mineral  acids  have  a  ten- 
dering action  on  cotton,  causing  a  disintegration  of  the  fiber  through  a 
breaking  down  of  the  cellulose  molecule  of  which  the  cotton  is  composed,  f 
The  compound  of  cellulose  so  formed  is  known  as  hydrated  cellulose  and  is 
brittle  in  nature.  On  this  difference  in  the  reaction  of  wool  and  cotton 
with  acids  is  based  the  process  of  "  carbonizing  "  or  separating  vegetable 

*  A  very  exhaustive  consideration  of  the  microscopical,  physical,  and  chemical 
properties  of  the  various  textile  fibers  is  to  be  found  in  the  author's  "Textile  Fibers." 
For  the  present  purpose  only  those  chemical  properties  of  the  fibers  will  be  considered 
which  possess  a  direct  bearing  on  the  processes  of  dyeing. 

t  With  strong  nitric  acid,  especially  if  mixed  with  sulphuric  acid,  cotton  reacts  in  a 
very  specific  manner,  giving  rise  to  nitrated  cotton,  or  gun-cotton.  This  is  used  as  an 
explosive  and  as  a  basis  for  cellulose  and  pyroxylin  products.  When  steeped  for  several 
hours  in  strong  nitric  acid  (84°  Tw.)  cotton  acquires  the  property  of  combining  directly 
with  acid  dyestuffs,  and  is  said  to  be  "animalized."  Such  a  process,  however,  has 
never  received  commercial  application,  as  it  is  impossible  to  avoid  injury  to  the  fiber. 

36 


ACTION   OF  ACIDS  ON   TEXTILES 


37 


fibers  from  a^ooI  in  woven  fabrics  or  in  shoddy  where  it  is  desired  to  recover 
the  wool  and  ehminate  the  cotton. 

Organic  acids  (such  as  formic,  acetic,  oxahc,  and  tartaric)  do  not  have 
the  same  tendering  action  on  cotton  as  the  mineral  acids;  formic  and 
acetic  acids,  being  both  volatile,  are  removed  from  the  fiber  on  drying  and 
hence  do  not' injure  cotton;  oxalic  and  tartaric  acids,  on  the  other  hand, 
are  not  volatile,  and  if  strong  solutions  are  used  somewhat  tender  the  cotton 
when  drying.     From  these  facts  it  may  readily  be  understood  that  when 


Fig.  33. — Skein  Mercerizing  Machine.     (German  Type.) 


it  is  necessary  to  employ  acid  solutions  in  connection  with  cotton,  it  is 
always  preferable  to  use  acetic  or  formic  acid  for  this  purpose. 

It  will  be  obvious  that  in  all  processes  of  dyeing  or  bleaching  where 
cotton  (or  other  vegetable  fibers)  comes  in  contact  with  solutions  contain- 
ing mineral  acids,  or  salts  of  an  acid  character,  it  is  always  necessary  to 
remove  completely  the  acid  by  thorough  washing  or  by  neutralizing  with 
an  alkali  before  the  cotton  is  allowed  to  dry ;  otherwise  the  fiber  will  become 
weakened.  This  is  frequently  the  source  of  much  trouble  in  bleaching 
and  dyeing. 


38 


CHEMICAL  STUDY  OF  THE  FIBERS 


What  has  been  said  with  reference  to  the  action  of  acids  on  cotton  is 
also  true  of  other  vegetable  fibers,  such  as  linen,  hemp,  jute,  etc.,  as  well 
as  artificial  silk. 

Silk  behaves  towards  acid  solutions  much  in  the  same  manner  as 
wool,  and  may  be  dyed  in  acid  dyebaths  without  special  injur}'.  It  is  also 
extensively  weighted  by  the  use  of  stannic  chloride,  a  salt  of  a  strongly 
acid  character.  Silk,  however,  is  not  as  resistant  as  wool  to  the  effect  of 
mineral  acid  solutions  drj'ing  into  the  fiber,  as  the  luster  is  liable  to  be 
affected,  therefore  all  such  acid  should  be  thoroughly  washed  out  of  the 


Fig.  34. — Yam  Mercerizing  Machine  with  Hj'draulic  Tension:  Automatic  Type. 

(J.  Kleinwefer's  Sons.) 


silk  before  dr\'ing.  In  the  case  of  hydrochloric  acid  the  silk  fiber  is  liable 
to  become  much  weakened  if  the  acid  is  allowed  to  concentrate  in  the  filler 
by  dr}'ing.  Weakened  silk  may  frequently  be  traced  back  to  this  source 
of  injur}',  especially  with  weighted  silk.*  Organic  acids  do  not  have  a 
tendering  effect  on  silk,  and  are  generally  to  be  recommended  for  use 
where  an  acid  is  required  in  a  treatment  of  this  fiber.  If  an  organic  acid 
is  allowed  to  dr>'  into  the  fiber  the  silk  acquires  a  "  scroop  " ;  that  is  to  say, 
it  gives  out  a  crunching  sound  when  squeezed.     Acetic  and  tartaric  acids 

*  Sometimes  the  weakening  effect  does  not  become  apparent  until  after  the  lapse 
of  considerable  time. 


ACTION  OF  TANNIC  ACIDS 


39 


are  particularly  used  in  this  connection.  Tlie  luster  is  also  increased,  espe- 
cially if  the  fiber  (generally  in  the  form  of  skein  yarn)  is  stretched  and 
steamed  after  drjdng.  This  acid  and  steaming  treatment  is  known 
as  "  brightening  "  the  silk. 

Tannic  acid  (and  the  vegetable  astringent  extracts  broadly  classified 
under  the  general  name  of  "  tannins  ")  has  a  rather  special  action  on  the 
textile  fibers,  differing  quite  radically  in  this  respect  from  the  other  organic 
acids.     Cotton  readily  absorbs  tannic  acid  from  solution  in  considerable 


Fig.  35. — Skein  Mercerizing  Machine.     (English  Form.) 


proportion,  and  though  most  of  the  acid  may  be  removed  from  the  cotton 
by  washing  in  fresh  water,  nevertheless  it  may  be  permanentlj^  fixed  in  the 
fiber  by  treatment  with  a  solution  of  a  metallic  salt  with  which  it  forms  an 
insoluble  tannate,  such  as  tartar  emetic  (antimony  potassium  tartrate) 
and  iron  salts  (copperas).  On  this  process  is  based  the  general  method 
of  mordanting  cotton  for  dyeing  with  the  basic  dyes,  and  the  method  is 
also  used  extensively  in  calico  printing.  Silk  also  absorbs  tannic  acid  very 
readily,  and  the  treatment  of  this  fiber  with  tannin  solutions  is  utiUzed  in 
the  weighting  of  silk  for  black  dyeing,  the  tannin  being  fixed  in  this  case 


40 


CHEMICAL  STUDY  OF  THE  FIBERS 


with  an  iron  salt.  Wool  also  combines  with  tannic  acid,  and  the  tannin 
may  be  fixed  with  tartar  emetic  or  tin  salts  (stannous  chloride).  Wool 
treated  in  this  manner  develops  the  peculiar  property  of  being  quite  inert 
towards  many  dycstuffs.  The  process  is  utilized  in  dyeing  in  what  is 
known  as  the  "  resist  "  method. 


Fig.  36. — Skein  Mercerizing  Machine.     (Swiss  Type.) 


2.  Action  of  Alkalies.— Alkalies  react  with  the  animal  and  vegetable 
fibers  in  just  the  opposite  manner  to  acids.  Caustic  soda,  even  in  very 
dilute  solutions  and  at  not  very  high  temperatures,  will  completely  dis- 
integrate and  dissolve  the  wool  fiber;  whereas  cotton  is  not  affected.  Even 
with  solutions  of  sodium  carbonate  (soda  ash)  the  wool  fiber  will  be  seri- 
ously weakened  and  injured  in  appearance  unless  such  solutions  are  com- 
paratively weak  and  employed  at  rather  low  temperatures.  Due  to  these 
facts  caustic  soda  cannot  be  used  for  the  scouring  of  wool,  nor  should 


MERCERIZING   OF  COTTON  41 

it  be  used  in  any  connection  with  wool.*  Soda  ash  when  employed  in 
scouring  or  any  other  process  in  contact  with  wool,  must  be  carefully 
handled  in  order  that  the  solution  of  the  same  does  not  become  too  concen- 
trated nor  heated  too  high.  Cotton,  on  the  other  hand,  is  not  weakened  by 
alkalies,  and  is  scoured  by  the  use  of  boiling  caustic  soda  or  soda  ash  with- 
out fear  of  being  injured.  Ammonium  carbonate  and  ammonia  water  are 
much  milder  in  their  alkaline  action  and  do  not  have  any  injurious  effect 
on  wool  at  ordinary  concentrations,  on  which  account  they  make  very  good 
scouring  compounds,  although  too  expensive  for  the  majority  of  materials. 

Concentrated  solutions  of  caustic  soda  (50°  Tw.  or  over)  when  used 
cold  have  a  peculiar  effect  on  wool;  the  fiber  is  not  dissolved,  but  the  luster 
is  greatly  increased  and  the  fiber  is  hardened  and  loses  its  felting  property 
to  a  considerable  degree.  The  strong  alkah  must  be  used  cold  and  must 
be  washed  out  of  the  fiber  quickly,  and  finally  completely  neutralized  by 
washing  in  dilute  acid.  This  process  is  made  use  of  in  the  so-called 
"  washing  "  of  Oriental  rugs;  the  rug  is  laid  out  and  swabbed  over  with  a 
strong  caustic  soda  solution,  which  is  then  washed  out  with  plenty  of  fresh 
water.  The  effect  is  to  reduce  the  high  colors  somewhat,  but  mostly  it  is 
to  give  the  woolen  nap  of  the  rug  a  good  luster.  The  process  is  to  be 
condemned,  as  it  injures  the  fiber,  and  making  it  brittle,  much  reduces  its 
life,  and  the  result  is  that  the  rug  rapidly  wears  out. 

Silk  is  injuriously  affected  by  alkalies  in  a  manner  similar  to  wool, 
only  the  fiber  does  not  dissolve  as  readily  in  solutions  of  caustic  soda; 
the  luster  and  strength,  however,  are  badly  impaired.  As  raw  silk  is 
scoured  in  very  strong  boiling  soap  solutions,  care  should  be  had  that  the 
soaps  employed  should  be  free  from  uncombined  alkali  in  order  that  the 
good  qualities  of  the  silk  may  be  preserved. 

3.  Mercerizing  of  Cotton. — When  cotton  is  treated  with  concen- 
trated solutions  of  caustic  soda  it  undergoes  a  peculiar  change,  known 
as  "  mercerization, "  derived  from  John  Mercer,  the  discoverer  of  the 
process.  If  cotton  (yarn  or  cloth)  is  steeped  in  a  cold  solution  of  caustic 
soda  of  50  to  55°  Tw.  for  several  minutes  and  then  thoroughly  washed 
free  from  the  alkali,  it  will  be  found  to  have  shrunk  very  considerably 
(from  10  to  25  per  cent  of  its  length)  and  to  have  greatly  increased  in 
stiength  (from  10  to  40  per  cent).  If  the  yarn  or  cloth  be  maintained 
in  a  stretched  condition  so  that  it  cannot  shrink  when  treated  with  the 
caustic  soda  solution,  and  then  washed  free  from  alkali,  still  in  the  stretched 
condition,  the  fiber  will  be  found  to  have  developed  a  high  degree  of  luster. 
This  is  especially  noticeable  in  cotton  goods  made  from  Egyptian  or  Sea 
Island  long-stapled  fiber.  This  process  is  extensively  used  in  practice 
for  the  production  of  mercerized  or  lustered  cotton. 

*  Soaps,  for  instance,  used  in  scouring  or  washing  wool  or  woolen  goods  should  not 
Qontain  any  free  alkali  (caustic  soda  or  caustic  potash). 


42 


CHEMICAL  STUDY  OF  THE  FIBERS 


There  are  two    general    methods    in    use    for   the    mereerization    of 
cotton  yarns  at  the  present  time.     The  first  and  older  method  is  that 


Fig.  37. — Lustering  Machine  for  Mercerized  Yam. 

of  mercerizing  tho  yarn  in  the  form  of  skeins,  and  this  requires  the  use  of 
a  skein  mercerizing  machine.  This  method  of  mercerizing  was  that  first 
employed  in  the  early  days  of  the  industry  in  Europe,  both  on  the  Conti- 


METHODS   OF   MERCERIZING 


43 


nent  and  in  England,  and  it  is  still  the  method  which  is  almost  exclusively 
used  in  the  former,  and  even  to  a  very  large  extent  in  England  to  the  pres- 
ent day.  The  second  method,  and  one  which  has  been  an  American 
development,  is  known  as  the  warp  process,  in  which  the  yarn  is  operated 
on  in  the  form  of  a  long  chain  or  warp  in  a  continuous  manner.  The  greater 
part  of  yarn  mercerized  in  America  at  the  present  time  is  made  according 


Fig.  38. — Skein  Mercerizer;  Vertical  Type.     (Pornitz.) 


to  the  warp  method,  there  being  but  a  comparatively  small  amount  of 
skein  mercerizing  done  in  the  United  States. 

The  skein  method  of  mercerizing  is  more  or  less  of  a  discontinuous 
process;  that  is  to  say,  the  various  operations  through  which  the  yarn 
is  required  to  pass  do  not  take  place  in  an  unbroken  sequence  on  the  same 
machine.  The  yarn,  for  instance,  is  first  boiled  out  in  the  ordinary  man- 
ner in  the  kier  or  tank,  as  is  customary  for  yarn  in  the  form  of  skeins  to  be 
used  for  bleaching  or  dyeing.     The  hanks  are  then  put  on  the  mercerizing 


44 


CHEMICAL  STUDY  OF  THE  FIBERS 


machine,  where  they  are  subjected  to  tension  and  treated  with  a  solution 
of  caustic  soda.    The  partial  operation  of  washing  is  also  carried  out  on 


Fig.  39— Skein  Wcrcerizer.     (Smith,  Drum  &  Co.) 


^^^^^^^^^^Hjl^^^^  '^^S 

'■=?gsfe'-      ^itm 


Fig.  40.— Warp  Mercerizer.     (Smith,  Drimi  &  Co.) 

the  machine  without  removal  of  the  skeins,  for  the  reason  that  the  first 
step  in  the  washing  or  removal  of  the  strong  solution  of  caustic  soda  from 


MERCERIZING   MACHINES 


45 


46 


CHEMICAL  STUDY  OF  THE  FIBERS 


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WARP  PROCESS  OF   MERCERIZING  47 

the  fiber  must  be  accomplished  while  the  yarn  is  still  under  a  state  of  ten- 
sion. The  skeins  are  then  removed  from  the  mercerizing  machine  and 
given  a  further  washing,  usually  in  an  ordinary  tank,  though  this  process 
may  also  be  effectually  conducted  in  a  skein  washing  machine.  After 
the  caustic  soda  solution  has  been  removed  from  the  fiber  as  far  as  practic- 
able by  washing,  the  yarn  is  next  soured  or  treated  in  a  bath  of  dilute 
sulphuric  acid,  usually  in  the  ordinary  form  of  tank.  This  is  for  the  pur- 
pose of  completely  neutralizing  the  residue  of  caustic  soda  which  is  still 
left  in  the  yarn  even  after  thorough  washing.  A  further  washing  oper- 
ation has  to  be  given  in  order  to  remove  any  excess  of  acid  from  the  fiber, 
and  also  to  take  out  the  sulphate  of  soda  which  is  produced  by  the  reaction 
of  the  acid  with  caustic  soda.  Finally  a  finishing  bath  is  given  the  yarn 
for  the  purpose  of  softening  the  fiber.* 

In  the  warp  process  the  yarn  is  first  made  up  into  long  warps  in  a  man- 
ner suitable  for  subsequent  quilling  if  the  yarn  is  to  be  converted  back 
into  packages  such  as  cones,  tubes,  or  skeins,  or  for  beaming  if  it  is  to  be 
employed  directly  for  weaving  warps.  These  warps  are  then  run  through 
the  warp  mercerizing  machine,  which  is  so  constructed  as  to  permit  of 
the  continuous  treatment  of  the  yarn  in  successive  compartments  to  the 
operation  of  boiling-out,  impregnation  with  the  strong  caustic  soda  solu- 
tion, washing,  souring,  washing  and  finishing.  In  some  cases,  for  special 
reasons,  the  boiling-out  compartments  are  separated  in  sequence  from  the 
rest  of  the  machine,  so  as  to  permit  of  the  ageing  of  the  yarn  between  the 
operations  of  boiling-out  and  treatment  with  the  caustic  soda  solution. 
But  even  in  this  case  the  remaining  operations  are  conducted  continu- 
ously and  in  seriatim.^ 

*  From  this  brief  outline  it  may  be  seen  that  there  are  quite  a  number  of  different 
operations  through  which  the  yarn  must  pass  in  the  process  of  mercerizing,  and  in 
the  skein  process  this  entails  considerable  handling  and  rehandling  of  the  yarn  back 
and  forth  between  the  different  baths  required.  To  the  American  idea  this  appears 
as  an  unwieldy  and  laborious  method,  entailing  far  too  much  hand  labor  to  be  economical 
in  practice.  It  was  natural  to  seek  for  a  more  continuous  process  in  which  the  yarn 
could  be  handled  economically  and  without  breaking  the  sequence  of  the  various  opera- 
tions. This  naturally  led  to  the  development  of  the  warp  method.  The  skein  method 
also  gave  but  a  comparatively  small  production  on  each  mercerizing  machine,  and 
there  was  a  considerable  lapse  of  time  in  which  the  machine  itself  was  not  actually  per- 
forming its  special  work;  that  is  to  say,  the  machine  was  practically  "dead"  during 
the  time  required  for  loading  and  unloading  the  skeins,  and  there  was  also  considerable 
time  consumed  when  the  machine  was  putting  on  and  taking  off  the  tension  on  the 
skeins. 

t  From  the  standpoint  of  mill  economy,  the  warp  process  has  many  marked  advan- 
tages over  the  skein  method  of  treatment.  With  respect  to  economical  conservation 
of  labor,  automatic  and  continuous  operation,  as  well  as  daily  output  of  product,  the 
skein  method  falls  far  behind  in  comparison  with  the  warp  process.  But  besides  all 
this,  there  is  another  consideration  which  has  proved  to  be  important,  especially  in 
American  practice,  and  this  is  evenness  of  the  product  with  respect  to  its  degree  of 


48  CHEMICAL  STUDY  OF  THE  FIBERS 

Cotton  Is  also  extensively  mercerized  in  the  form  of  cloth,  for  which 
purpose  special  machines  are  used.  The  goods  (after  singeing  and  pre- 
paring) are  padded  with  the  strong  caustic  soda  solution  and  then  carried 
on  to  a  tenter  frame  which  keeps  the  cloth  in  a  state  of  tension  while  it 
is  w\ashed  and  soured.  The  cloth  is  then  well  washed  and  finished  in 
the  usual  machines. 

Cotton  cloth  is  mercerized  to  a  great  extent  not  only  for  the  purpose 
of  giving  the  fiber  a  high  luster,  but  also  for  the  purpose  of  increasing  the 
dyeing  qualities  of  the  goods  and  for  the  purpose  of  obtaining  a  trans- 
lucent finish  on  such  goods  as  cotton  lawns,  voiles,  etc. 

The  mercerizing  of  cotton  cloth  in  the  piece,  as  far  as  the  principles 
of  the  treatment  are  concerned,  is  exactly  similar  to  that  of  mercerizing 
cotton  in  the  form  of  yarn.  There  is,  however,  a  radical  difference  in  the 
method  of  treatment,  necessitated,  of  course,  by  the  form  of  the  material 
to  be  handled. 

mercerization.  In  the  skein  process  we  must  bear  in  mind  that  the  individual  unit  is 
the  single  hank  or  skein,  and  consequently  the  process  deals  with  a  large  number  of  small 
units  as  compared  with  the  warp  process,  where  the  whole  warp  itself  forms  the  unit 
on  which  to  operate.  The  sub-division  of  the  3'arn  into  small  units,  of  course,  allows  of 
great  possibility  in  the  matter  of  uneven  treatment  of  the  separate  skeins;  whereas 
this  is  minimized  in  the  case  of  warps  where  onlj'  a  few  large  units  are  dealt  with  at  a 
time.  Fiu-thermore,  the  frequent  interruption  in  the  continuity  of  the  process  and 
rehandling  of  the  yarn  in  the  skein  method  may  also  permit  uneven  treatment  to  creep 
in.  But  besides  all  this  we  have  to  consider  the  difference  in  the  makeup  of  the  j'arn 
in  the  two  cases.  The  skein  consists  of  a  single  strand  wound  round  and  round  and 
overlapping.  The  laps  of  the  yarn  around  the  skein  are  approximately  equal  in  length, 
especially  when  carefully  wound,  as  would  necessarily  be  the  case  when  the  skein  has 
been  prepared  with  a  view  to  mercerizing  and  when  the  skein  is  kept  rather  small  in  size. 
But  this  "approximate  equahty"  in  length  allows  of  sufficient  deviation  to  give  an 
unequal  tension  on  the  individual  strands  when  the  skein  as  a  whole  is  stretched  over 
the  rolls  of  the  mercerizing  machine.  Furthermore,  the  skein  is  generally  wound  in 
such  a  manner  that  the  laps  are  laid  spirally  back  and  forth  the  width  of  the  skein,  and 
this  diagonal  position  across  the  line  of  tension  must  necessarily  cause  a  slippage  of  the 
strands  when  they  are  revolving  in  a  stretched  condition  around  the  rollers  of  the  mer- 
cerizing machine  in  the  caustic  soda  solution.  Consequently,  it  may  be  seen  from  the 
very  makeup  of  the  skein  there  is  a  condition  permitting  of  uneven  tension,  and  hence 
uneven  mercerizing.  This  condition  is  reduced  to  a  minimum  when  the  yarn  is  straight- 
wound  in  the  skein,  rather  than  cross-wound,  and  when  the  skein  is  kept  to  a  small  bulk 
so  that  there  is  not  much  overlapping  of  the  strands  on  one  another.  This  also  sup- 
poses, of  course,  that  during  the  reeling  of  the  skein  an  even  tension  has  been  main- 
tained on  the  yarn. 

In  the  makeup  of  the  warp  the  condition  of  the  yarn  is  very  different.  In  the  first 
place  the  several  strands  of  the  yarn  run  through  the  warp  in  a  fairly  parallel  manner, 
so  that  the  direction  of  the  yarn  is  in  the  line  of  tension  as  applied  to  the  warp.  In  the 
second  place,  each  strand  in  the  warp  is  a  separate  and  distinct  thread,  so  that  the  thread, 
even  in  passing  over  the  rollers  of  the  machine,  does  not  overlap  on  itself  as  is  the  case  in 
the  skein,  so  there  is  no  chance  of  binding  and  uneven  tension  by  the  take-up  of  one  lap 
on  another. 


MERCERIZING  OF  CLOTH 


49 


From  what  has  been  stated  on  the  mercerizing  of  cotton  yarns,  it  will 
be  readily  understood  that  the  mercerizing  of  cotton  cloth  in  the  piece 
requires  the  following  processes: 

(1)  Treatment  of  the  cloth  to  a  preHminary  boiling-out  process  whereby 
the  fiber  is  brought  into  such  a  condition  as  to  be  readily  absorbent  of  the 
mercerizing  liquors.  In  the  case  of  the  heavier  weaves  of  cloth,  this  boiling- 
out  process  must  be  especially  thorough,  otherwise  the  mercerizing  liquors 
will  not  penetrate  uniformly  and  completely  through  the  mass  of  the 
fabric  and  this  will  lead  to  bad  work. 


Fig.  43.— Mercerizing  Paddle,  3-Roll.     (Textile-Finishing  Machinery  Co.) 


(2)  Saturation  of  the  cloth  with  a  caustic  soda  solution  of  55  to  60° 
Tw.  This  treatment  is  usually  accomplished  in  a  special  form  of  padding 
machine  provided  with  suitable  squeeze  rolls  so  as  to  force  the  caustic 
hquor  well  into  the  fiber  of  the  goods.  This  solution  is  the  mercerizing 
bath,  and  the  temperature  must  be  maintained  below  70°  F.,  and  the  den- 
sity or  strength  of  the  liquor  must  be  kept  at  a  constant  point  by  proper 
circulation  and  additions  of  stronger  solutions  to  make  up  for  the  caustic 
soda  which  is  taken  up  in  combination  with  the  cotton. 

(3)  Application  of  tension  to  the  cloth  immediately  after  it  has  become 
saturated  with  the  caustic  soda.     This  tension  must  also  be  appKed  in 


50 


CHEMICAL  STUDY  OF  THE  FIBERS 


both  the  direction  of  the  warp  as  well  as  that  of  the  filling,  for  both  threads 
must  be  kept  under  proper  tension  to  prevent  shrinkage  in  either  length 
or  width.  It  is  only  in  this  manner  that  a  proper  degree  of  mercerizing 
can  be  brought  about;  for  if  tension  is  applied  in  the  warp  direction  alone, 
these  threads  will  be  mercerized  and  lustered,  whereas  the  filling  threads 
will  shrink  considerably,  causing  the  cloth  to  pucker,  and  furthermore 
these  threads  will  not  receive  any  luster,  and  the  mercerizing  of  the  cloth 
as  a  whole  will  be  sadly  defective. 

(4)  Treatment  of  the  cloth  with  wash  waters  for  the  purpose  of  com- 
pleting the  mercerizing  action  and  removing  the  majority  of  the  caustic 


Fig.  -44. — Machine  for  Lustering  by  Schreiner  Process.     (German  Type.) 


soda  liquors  from  the  goods.  This  washing,  or  at  least  the  first  portion  of 
the  washing,  must  be  carried  out  while  the  cloth  is  still  maintained  in  a 
state  of  tension,  otherwise  the  goods  will  shrink  up  and  the  mercerizing 
effect  will  be  lost. 

(5)  Treatment  of  the  cloth  with  a  dilute  solution  of  acid  for  the  pur- 
pose of  removing  the  last  traces  of  the  caustic  soda  from  the  cloth.  This 
treatment  is  not  carried  out  with  the  cloth  in  a  state  of  tension,  as  after 
the  majority  of  the  caustic  soda  has  been  removed  by  the  washing  with 
water,  the  mercerizing  reaction  is  completed  and  the  fiber  is  set  in  its  per- 
manently mercerized  form;  consequently  the  tension  is  no  longer  necessary. 


MERCERIZING   OF   CLOIH 


51 


In  fact,  the  cloth  at  this  point,  that  is  to  say,  when  the  treatment  with  acid 
is  carried  out,  shows  a  tendency  to  stretch  out  somewhat,  rather  than 
contract. 

(6)  A  final  finishing  operation,  usually  employing  a  softening  com- 
pound for  the  purpose  of  neutralizing  any  excess  of  acid,  and  also  for  the 
purpose  of  softening  the  fiber,  which  is  rendered  rather  harsh  by  the 
treatment  with  the  caustic  soda  as  well  as  the  acid  baths.  This  operation 
may  be  considered  as  completing  the  mercerizing  process  proper.    The 


Fig.  45. — Hydraulic  Schreiner  Calender.     (Textile-Finishing  Machinery  Co.) 


processes  of  calendering,  stiffening,  embossing,  etc.,  which  may  follow 
after  the  mercerizing,  are  to  be  considered  further  processes  of  finishing, 
and  cannot  be  included  within  the  scope  of  the  mercerizing  itself. 

The  boiling-out  of  cloth  for  mercerizing  has  to  be  done  with  more  care 
and  thoroughness  than  is  the  case  with  yarn.  This  is  on  account  of  the 
fact  that  the  impurities  in  cloth  are  of  a  different  character  and  of  nuich 
greater  amount  than  with  yarn.  While  yarn  has  only  the  natural  impuri- 
ties of  the  fiber,  cloth  contains  a  quantity  of  sizing  used  for  facilitating 
the  weaving  operations.  This  size  consists  of  various  mixtures  of  starch, 
fats,  and  gums,  and  is  somewhat  difficult  to  remove  thoroughly.     There- 


52  CHEMICAL  STUDY  OF  THE  FIBERS 

fore,  as  a  rule,  a  simple  boiling  of  the  cloth  in  soap  solution,  or  soluble  oil, 
or  a  dilute  solution  of  alkali  is  not  sufficient  as  is  the  case  with  yarns.  The 
cloth  must  be  subjected  to  a  very  thorough  kier  boiling  in  a  manner 
similar  to  that  used  previous  to  bleaching  cloth.  A  good  soda  boil  in  a 
high  pressure  kier  for  six  to  eight  hours  is  required.  This  will  decompose 
the  starchy  matter  and  saponify  the  fats  and  oils  which  may  have  been 
used  in  the  size.  After  the  boiling,  a  good  washing  must  be  given  in  order 
to  remove  all  the  decomposed  matters.  The  boiling  of  cotton  cloth  pre- 
vious to  mercerizing  should  be  always  carried  out  with  the  purpose  of 
obtaining  as  clean  and  pure  a  cloth  as  possible;  impurities  of  any  kind 
will  act  in  a  detrimental  manner  in  the  mercerizing  process,  and  cause 
defects  to  arise  in  the  cloth  as  well  as  giving  deficient  luster,  the  real  object 
of  the  mercerizing  process. 

The  saturation  of  the  cloth  with  the  mercerizing  or  caustic  soda  solu- 
tion must  be  carried  out  with  care  and  intelligence,  for  if  the  cloth  is  not 
evenly  and  thoroughly  saturated  the  mercerizing  or  luster  will  not  be  pro- 
duced with  uniformity  and  defective  cloth  will  be  the  result.  The  machine 
employed  for  saturation  is  of  a  special  type  built  for  this  immediate  pur- 
pose. It  is  a  mangle  usually  with  three  bowls,  the  middle  roll  consisting 
of  iron  and  the  other  two  of  hard  rubber.  Care  must  be  had  that  the  rolls 
are  very  even  across  their  width,  as  otherwise  the  cloth  would  become 
unevenly  saturated.  The  running  of  the  cloth  through  the  mangle  should 
be  so  arranged  that  the  piece  gets  two  to  three  dips  in  the  caustic  soda 
solution  with  heavy  squeezes  between  each  dip.  The  caustic  soda  solution 
in  the  mangle  must  be  maintained  at  a  constant  strength  and  cooled  by 
means  of  circulation  through  a  large  reservoir  of  caustic  soda,  as  was 
explained  in  the  case  of  yarn  mercerizing.  Artificial  cooling  of  the  liquor 
in  the  mangle  box  is  not  necessary  if  this  circulation  is  properly  conducted. 

In  the  case  of  Ught-weight  fabrics  like  muslins,  lawns,  and  shirtings, 
it  will  only  be  necessaiy  to  take  the  cloth  through  the  saturating  mangle 
once,  so  these  goods  can  then  be  taken  straight  away  from  the  mangle  to 
the  tenter  frame  for  the  purpose  of  putting  on  the  required  degree  of  ten- 
sion. But  with  heavy  goods,  it  will  often  be  necessary  to  pass  the  cloth 
through  the  mangle  twice  before  being  fed  into  the  tenter. 

The  tenter  frame  should  be  provided  with  special  clips  for  mercerizing 
being  made  entirely  of  iron,  as  the  usual  brass  clips  would  be  rapidly 
attacked  by  the  strong  caustic  soda  liquors.  These  clips  must  also  be  espe- 
cially strong  and  so  adapted  that  a  very  considerable  tension  can  be  put 
on  the  cloth.  The  usual  form  of  tenter  employed  for  mercerizing  ranges 
is  of  the  self-feeding  type;  but  even  with  this,  it  is  necessary  that  great 
care  be  had  that  the  clips  take  up  the  cloth  evenly  and  tightly,  and  it  is 
necessary  to  have  a  careful  workman  give  this  point  his  constant  attention. 
If  this  is  neglected  there  will  be  streaks  across  the  cloth  owing  to  irregular 


MERCERIZING   BY  SCHREINERING   PROCESS  53 

mercerizing ;  a  defect  which  will  be  emphasized  if  the  cloth  is  subsequently 
dyed  in  light  colors.  The  tenter  frame  is  usually  about  40  feet  in  length 
and  will  get  off  about  10,000  to  15,000  yards  of  cloth  per  day.  As  the 
cloth  passes  along  the  tenter  frame  under  tension,  it  is  first  stretched  out 
to  its  required  width,  then  travels  along  at  an  even  tension  for  some  time. 
After  traveling  about  half  the  length  of  the  frame,  the  cloth  is  then  sub- 
jected to  the  action  of  water  through  spray  pipes  a'oove  and  below.  The 
first  washing  of  this  kind  is  usually  done  with  warm  water,  and  the  wash 
waters  are  caught  in  a  basin  l^elow  the  machine. 

When  the  cloth  comes  off  the  tenter  the  most  of  the  caustic  soda  should 
have  been  removed  from  the  cloth,  after  which  the  mercerizing  action 
proper  is  finished,  and  the  tension  can  be  removed.  Coming  from  the 
tenter  frame,  the  cloth  is  next  passed  into  a  washing  box  where  it  receives 
a  further  good  washing  with  cold  water,  the  cloth  of  course  being  kept  in 
the  open  width  in  all  these  operations  after  leaving  the  tenter  frame. 
From  the  washing  box,  the  cloth  is  carried  through  a  similar  box  con- 
taining a  solution  of  dilute  sulphuric  acid  for  the  purpose  of  neutralizing 
the  final  trace  of  alkali  which  is  practically  impossible  totally  to  remove 
by  washing  in  water  alone.  The  strength  of  the  acid  should  be  so 
adjusted  as  to  leave  but  a  slight  excess  of  acid  in  the  cloth  after  the  alkali 
is  neutralized.  A  further  washing  with  cold  water  is  now  required  to 
remove  the  excess  of  acid,  and  the  process  may  then  be  considered  as 
finished  as  far  as  the  mercerizing  process  is  concerned. 

Frequently  a  further  lustering  operation  is  given  the  mercerized  cloth 
by  a  special  method  of  calendering,  known  as  "  Schreinering."  This 
consists  essentially  of  calendering  the  cloth  with  a  hot  steel  roll  which  is 
engraved  with  very  fine  lines  running  about  250  per  inch.  The  direction 
of  the  lines  usually  runs  at  an  angle  to  the  length  of  the  cloth,  and  is  more  or 
less  conditioned  by  the  direction  of  the  twist  in  the  yarn  to  get  the  best 
results.  This  operation  is  practically  embossing  the  cloth  in  a  pattern 
made  up  of  fine  diagonal  lines  so  close  together  as  to  be  invisible  to  the  eye. 
The  effect  is  greatly  to  enhance  the  luster,  as  it  causes  a  peculiar  reflection 
of  the  light  rays.  The  Schreinering  process  can  l)e  carried  out  on  cloth 
independently  of  mercerizing,  and  is  used  to  a  great  extent,  for  it  produces 
a  fabric  which  has  a  luster  and  appearance  very  closely  resembling  a  silk 
fabric,  and  therefore  it  has  come  into  great  demand. 

4.  Action  of  Metallic  Salts  on  Fibers. — Wool  is  quite  reactive  towards 
solutions  of  most  metallic  salts,  absorbing  many  of  them  from  solution 
and  fixing  the  oxide  of  the  metal  in  chemical  combination  with  the  fiber. 
For  instance,  when  wool  is  boiled  with  a  dilute  solution  of  potassium  or 
sodium  bichromate  (chrome),  the  latter  salt  becomes  decomposed  to  a  con- 
siderable extent  and  quite  a  proportion  of  chromium  oxide  becomes 
chemically  combined  with  the  fiber.     This  fact  is  evidenced  by  the  wool 


54  CHEMICAL  STUDY  OF  THE  FIBERS 

showing  the  presence  of  the  metalUc  compound  by  its  color  and  by  being 
able  to  form  a  color-lake  with  certain  dyestuffs  which  will  not  combine 
directly  with  ordinary  wool. 

Solutions  of  neutral  salts  such  as  sodium  chloride  (common  salt), 
sodium  sulphate  (glaubersalt),  magnesium  sulphate,  etc.,  have  no  appa- 
rent action  on  wool;  only  traces  of  these  salts  are  absorbed  by  wool  from 
solution,  and  they  are  readily  washed  out  with  water.  Salts  of  the  heavy 
metals,  such  as  aluminium,  iron,  copper,  tin,  lead,  manganese,  zinc,  etc., 
act  in  much  the  same  manner  as  chrome,  in  that  the  wool  absorbs  the 
metallic  base  in  the  form  of  a  mordant.  Some  of  these  salts  tend  to  make 
the  wool  harsh,  as  is  the  case  with  stannous  chloride,  which  makes  the  wool 
fiber  rather  harsh  and  brittle  unless  used  in  small  amounts. 

Cotton,  on  the  other  hand,  has  but  veiy  slight  affinity  for  metallic 
salts,  being  very  inert  in  this  connection,  as  the  fiber  does  not  appear  to 
be  able  to  absorb  and  fix  the  metallic  oxide  as  in  the  case  of  wool.  Cotton 
is  rather  easily  dissolved  by  a  solution  of  copper  oxide  in  ammonia  (cup- 
rammonium  solution,  or  Schweitzer's  reagent),  from  which  it  is  precipitated 
in  a  gelatinous  state  by  addition  of  acids.  On  this  reaction  is  based  the 
method  of  preparing  artificial  silk  by  the  cuprammonium  method  (the 
so-called  "  glanzstoff  "  silk);  also  the  method  of  waterproofing  canvas  by 
the  Willesden  process  whereby  the  cloth  is  given  a  superficial  treatment 
with  the  cuprammonium  solution. 

The  reaction  of  wool  with  metallic  salts  forms  the  basis  of  the  opera- 
tions of  mordanting  wool  preliminary  to  the  dyeing  with  the  alizarine  and 
other  mordant  colors  which  require  a  base  of  some  metallic  oxide  with 
which  to  form  a  color-lake;  and  also  due  to  the  inert  character  of 
cotton,  this  fiber  cannot  be  readily  dyed  with  these  colors. 

Silk,  in  its  behavior  towards  metallic  salts,  is  very  similar  to  wool; 
that  is  to  say,  it  absorbs  the  salt  from  solution  and  the  metallic  base  is 
permanently  fixed  in  the  fiber.  This  reaction  is  the  basis  of  the  methods 
of  mordouidng  and  weighting  silk.  The  so-called  "  nitrate  of  iron  " 
(really  a  basic  ferric  sulphate)  in  conjunction  with  tannic  acid  is  largely 
used  for  weighting  black-dyed  silk;  while  stannic  chloride  ("  dynamite  ") 
is  generally  employed  for  weighting  white  or  light-colored  silk.  A  very 
concentrated  solution  of  zinc  chloride  (140°  Tw.)  rapidly  dissolves  silk 
and  may  be  used  for  estimating  this  fiber  in  the  presence  of  wool  and 
cotton. 

5.  Action  of  Chlorine  Compounds  and  Oxidizing  Agents. — Bleaching 
powder  has  a  peculiar  action  on  wool;  this  chemical  is  a  strong  oxidizing 
agent  and  in  hot  solutions  of  any  considerable  concentration  will  rapidly 
disintegrate  the  wool  fiber.  In  cold  and  dilute  solutions,  however,  a 
chemical  reaction  apparently  takes  place  between  the  wool  and  the  chlorine 
evolved  by  the  bleaching  powder,  giving  a  product  known  as  "  chlored  " 


CHLORINATED  WOOL  55 

or  "  chlorinated  "  wool  without  much  physical  alteration  of  the  fiber.* 
Wool  so  treated  exhibits  a  much  stronger  affinity  towards  many  coloring 
matters,  and  almost  completely  loses  its  felting  properties,  and  acquires 
a  higher  luster.  The  process  of  chlorinating  wool  is  extensively  employed 
at  the  present  time  for  producing  unshrinkable  woolen  garments  (chiefly 
underwear).  For  this  purpose  a  solution  of  hypochlorite  of  soda  is  gen- 
erally used,  to  which  hydrochloric  acid  is  added.  The  yellow  color  pro- 
duced on  the  goods  by  this  treatment  is  removed  by  sodium  bisulphite 
solution,  and  the  fabric  is  finally  softened  by  a  scouring  with  soap.  The 
solution  of  sodium  hypochlorite  may  be  prepared  in  the  following  manner: 
First  prepare  a  solution  of  160  lbs.  bleaching  powder  at  14°  Tw.  and  add  to 
tliis  100  lbs.  of  soda  ash,  gradually  and  with  constant  stirring.  Then 
allow  to  settle  and  decant  the  clear  liquor  for  use.  It  is  not  well  to  use  a 
solution  of  bleaching  powder  of  greater  strength  as  there  is  then  likelihood 
of  sodium  chlorate  being  formed,  which  is  very  objectionable  by  reason  of 
its  yellowing  action  on  the  wool.  The  solution  of  sodium  hypochlorite 
prepared  as  indicated  will  contain  about  4  per  cent  of  available  chlorine 
and  show  a  density  of  18°  Tw.  In  the  treatment  of  the  wool  about  |  to  1 
pint  of  this  solution  will  be  required  for  each  pound  of  fabric.  Hydro- 
chloric acid  is  also  added  gradually  in  amount  equal  to  about  two-thirds 
of  the  hypochlorite  used.  It  is  best  to  add  both  the  hypochlorite  and  the 
acid  in  several  portions.  The  goods  are  treated  for  five  to  six  minutes, 
cold.  They  are  then  well  washed  and  treated  in  a  bath  containing  1  gallon 
sodium  bisulphite  solution  (32°  Tw.)  per  100  lbs.  of  wool.  A  pint  of  sul- 
phuric acid  diluted  with  water  is  also  added  slowly  to  this  bath.  The 
goods  are  well  washed  again,  and  finally  scoured  in  a  warm  bath  containing 
soap  and  a  httle  soda  ash,  and  rinsed,  f     The  chlorination  of  wool  under 

*  This  treatment  of  wool  is  perhaps  not  really  a  "  chlorination  "  process,  but  rather 
one  of  oxidation ;  that  is  to  say,  the  chlorine,  as  such,  probably  does  not  combine  with 
the  wool,  but  simply  oxidizes  it.  This  treatment  causes  the  surface  scales  of  the  wool 
fiber  to  fuse  together  more  or  less  and  thus  lose  their  sharp  serrated  edges.  This  would 
account  for  the  increased  luster  and  the  loss  of  felting  property.  Chlorinated  wool 
can  readily  be  distinguished  from  ordinary  wool  by  the  use  of  the  following  simple 
tests:  (1)  If  a  single  drop  of  water  be  placed  on  a  fabric  of  chlorinated  wool,  it  is  quickly 
absorbed  and  the  wet-out  part  is  circular  in  form;  with  ordinary  wool  the  water  is 
absorbed  very  slowly  and  the  wet-out  part  is  irregular  in  outline.  (2)  If  a  fabric  of 
chlorinated  wool  is  wet-out  and  two  surfaces  of  it  are  rubbed  between  the  finger  and 
the  thumb  a  characteristic  "  scroop  "  is  felt.  (3)  If  chlorinated  and  ordinary  wool  are 
dyed  together  a  very  marked  difference  in  color  is  noted.  (4)  If  dry  chlorinated  and 
dry  ordinary  wool  are  rubbed  together  a  sufficient  charge  of  electricity  will  be  developed 
violently  to  disturb  an  electroscope.  Two  pieces  of  ordinary  wool  when  thus  rubbed 
show  no  charge. 

t  Another  method  given  for  the  preparation  of  chlorinated  wool  is  as  follows:  Treat 
the  wool  first  in  a  bath  containing  1^  lbs.  of  hydrochloric  acid  (cone.)  for  every  10  gallons 
of  water.     Squeeze  and  work  in  a  bath  containing,  for  100  lbs.  hard-fibered  wool,  15  to 


56  CHEMICAL  STUDY  OF  THE  FIBERS 

the  best  conditions,  however,  materially  injures  the  wearing  qualities  of 
the  garment.  This  is  not  so  much  due,  perhaps,  to  an  actual  rotting 
of  the  fiber,  as  it  is  to  the  removal  of  the  felting  property,  so  that  the 
mechanical  action  of  weaving  and  washing  tends  to  detach  the  fibers  from 
one  another.  Owing  to  the  strong  reaction  of  chlorine  compounds  with 
wool,  materials  like  bleaching  powder  and  sodium  hypochlorite  cannot  be 
employed  for  purposes  of  bleaching  this  fiber;  in  fact  hypochlorites  do  not 
bleach  the  wool  fiber  at  all,  but  give  it  a  deeper  yellow  tinge. 

Chlorine  compounds  (like  bleaching  powder,  etc.),  also  attack  silk, 
and  do  not  bleach  it. 

Cotton  docs  not  combine  with  the  chlorine  of  the  bleaching  powder, 
but  shows  the  strong  oxidizing  action  of  the  latter  in  becoming  bleached. 
This  reaction  is  the  basis  of  the  method  of  bleaching  cotton  materials  as 
well  as  all  the  other  vegetable  fibers. 

Oxidizing  agents,  such  as  sodium  and  hydrogen  peroxide  and  potassium 
permanganate,  when  employed  in  moderately  dilute  solutions,  have  no 
especially  injurious  action  on  any  of  the  textile  fibers,  though  they  have  the 
effect  of  destroying  or  bleaching  out  the  natural  coloring  matter  that  tints 
the  raw  fiber  a  yellowish  or  brownish  tone.  On  this  account  the  perox- 
ides of  both  sodium  and  hydrogen  are  extensively  employed  for  the  bleach- 
ing of  wool  and  silk  materials ;  they  could  also  be  employed  for  the  bleach- 
ing of  cotton  (and  the  vegetable  fibers  in  general)  but  they  are  not  as 
efficient  or  as  cheap  in  this  respect  as  hypochlorites.  Potassium  per- 
manganate may  also  be  utilized  for  bleaching  wool  and  silk,  though  in 
this  case  the  manganese  oxide  left  in  the  fiber  must  be  removed  by  a  treat- 
ment with  oxalic  acid  or  a  solution  of  sodium  bisulphite.  The  oxidizing 
action  of  permanganate  is  also  too  severe  to  give  a  safe  bleaching,  as  the 
fiber  is  liable  to  be  made  harsh  ond  tendered.  This  is  also  true  with 
regard  to  the  action  of  permanganate  on  cotton  and  the  vegetable  fibers, 
especially  the  bast  fibers  that  are  composed  of  several  cells.  In  this  case 
the  strong  oxidizing  action  of  the  permanganate  together  with  the  action 

20  lbs.  of  bleaching  powder  to  350  gallons  of  water,  or  for  soft-fibered  wools,  20  to  25  lbs. 
of  bleaching  powder  to  475  gallons  of  water.  The  bleaching  powder  solution  should 
have  a  strength  of  0.6  to  1 .0°  Tw.  Work  in  this  bath  for  one-half  hour,  then  add  3  ozs.  of 
hydrochloric  acid  per  10  gallons  of  bath  and  run  for  ten  minutes  longer.  Next  re-enter 
the  first  acid  bath  to  which  has  been  added  8  ozs.  of  hydrochloric  acid  per  10  gallons  of 
water.  Work  for  fifteen  minutes  then  wash  well  in  cold  water.  If  the  odor  of  chlorine 
is  still  perceptible  in  the  wool  it  is  advisable  to  treat  it  for  fifteen  minutes  in  a  bath  con- 
taining 2  per  cent  (on  the  weight  of  the  wool)  of  sodium  bisulphite  (36°  Be.),  then  rinse 
well  again.  If  wool  yarn  chlorinated  in  this  manner  is  woven  with  ordinary  wool  yarn 
and  then  dyed  in  the  piece,  a  two-color  effect  will  be  obtained,  owing  to  the  chlorinated 
wool  taking  on  a  much  heavier  shade  than  the  untreated  wool.  Also  if  the  piece  is 
suitably  woven  in  pattern  effect  and  fulled,  the  chlorinated  wool  will  not  felt  together 
like  the  other  wool,  but  will  stand  out  sharply  in  the  woven  pattern.  In  this  manner 
many  novel  effects  in  dyeing  and  finishing  may  be  produced. 


EFFECT  OF   MOISTURE   ON   TEXTILES 


57 


of  the  sodium  bisulphite  is  Hable  to  break  down  the  intercellular  matter 
between  the  separate  cells  and  cause  a  disintegration  of  the  fiber. 

6.  Effect  of  Moisture   on  Textile    Fibers. — Wool,   cotton,   and  silk 
will  all  absorb  considerable  quantities  of  moisture  from  the  air.     This 


^ 


P  — E 


"W 


Fig.  46. — Emerson  Textile  Conditioning  Oven. 


ability  to  absorb  moisture  is  known  as  their  hygroscopic  property,  and  it 
has  an  important  influence  on  the  various  operations  to  which  textile 
materials  are  subjected.  As  the  quantity  of  moisture  the  fibers  will  con- 
tain varies  with  the  atmospheric  conditions,  this  hygroscopic  quality  also 
has  considerable  influence  on  the  true  weight  of  any  given  amount  of 


58 


CHEMICAL  STUDY  OF  THE  FIBERS 


1 


C 
C 


Pi 


CONDITIONING   OF   TEXTILES 


59 


material,  consequently  it  has  an  important  bearing  on  the  proper  valuation 
of  these  fibers  in  commercial  transactions  where  they  are  bought  and  sold 
by  weight.  Under  normal  atmospheric  conditions  (about  70°  F.  tem- 
perature and  70  per  cent  humidity),  wool  will  contain  about  12  per  cent 
of  moisture,  cotton  about  5  to  6  per  cent,  and  silk  about  12  per  cent.  In 
trading  in  wool  and  silk  it  is  usual  to  have  a  certain  standard  of  moisture 
allowed  (known  ?.s  regain).  The  determination  of  this  is  known  as  con- 
ditioning, and  is  carried  out  by  drying  the  material  in  a  suitable  oven  so 
that  all  the  moisture  is  driven  off.     To  the  dry  weight  thus  obtained  there 


Fig.  48.— Yarn  Truck  Dryer  for  Cotton,  Wool,  Worsted  and  Silk  Yarns,  Tapes,  etc. 
(Philadelphia  Textile  Machinery  Co.) 


is  added  the  regain  allowed  and  this  is  known  as  the  conditioned  weight. 
In  this  country  the  standard  regain  for  silk  is  11  per  cent,  and  for  wool 
12  per  cent,  though  the  latter  varies  according  to  circumstances. 

In  the  manufacturing  operations  the  working  qualities  of  the  fibers 
are  largely  affected  by  moisture.  In  the  spinning  of  fine  cotton  yarns 
it  is  necessary  to  have  very  humid  conditions  so  that  the  fiber  may  be 
kept  moist  and  plastic.  In  the  processing  of  wool  and  silk  also  especial 
attention  must  be  paid  to  this  feature.  So  important  is  this  for  the  pro- 
duction of  uniform  and  good  quality  material  that  at  the  present  time  all 
well-organized  textile  mills  are  equipped  with  suitable  conditioning  systems 


60 


CHEMICAL  STUDY  OF  THE  FIBERS 


whereby  a  proper  and  uniform  moisture  condition  can  be  maintained, 
otherwise  the  (luality  of  the  product  would  vary  from  day  to  day  with 
variations  in  llic  humidity  of  the  air. 

In  the  carcHng,  spinning,  and  twisting  of  cotton  and  woolen  yarns  a 
considerable  amount  of  heat  is  developed  by  the  friction  of  the  fibers.  This 
causes  the  fibers  to  become  dry;  in  the  case  of  cotton  the  amount  of  mois- 
ture may  run  as  low  as  3  to  4  per  cent  and  with  wool  6  to  8  per  cent.  This 
is  a  needless  loss  in  weight  if  the  yarn  is  to  be  sold  hnmediately,  for  the 


Fig.  49. — Automatic  Yarn  Dryor  with  Thormostatio  Temperature  Control. 
(Philadelphia  Drying  Machinery  Co.) 


normal  amount  should  be  about  G  per  cent  for  the  cotton  and  12  per  cent 
for  the  wool.  This  lack  of  moisture  also  makes  the  yarns  harsh  and  more 
brittle,  thus  reducing  tlunr  good  wearing  {]ualities  and  softness  of  handle 
and  texture.  It  is  beneficial  in  such  cases  to  condition  the  yarn.  This 
is  usually  done  l)y  placing  the  yarn  (on  cops  or  tubs  or  in  hanks)  in  a  moist 
atmosphere  until  they  regain  the  proper  weight  in  moisture. 

In  the  finishing  and  drying  of  textile  fabrics  of  all  kinds  this  matter 
of  moisture  in  the  fiber  has  always  an  important  bearing.  If  the  fiber 
is  dried  down  to  a  bone-dry  condition  it  is  very  liable  to  become  perma- 


EFFECT  OF  HEAT  ON  FIBERS 


61 


nently  deteriorated  in  quality  and  sometimes  (especially  with  wool  and 
silk)  discolorations  will  be  produced.  It  is  not  proper  in  drying  oper- 
tions  to  carry  the  moisture  content  much  below  that  which  would  be  nor- 
mal under  atmospheric  conditions. 

The  electrical  condition  of  the  textile  fibers  is  also  greatly  influenced 
by  their  hygroscopic  conditions.  When  the  fibers  are  very  dry  they 
easily  become  highly  electrified  and  are  difficult  to  handle  in  carding  and 
spinning  and  winding.     This  electrification  is  especially  noticeable  in  the 


Fig.  50. — Upright  Drying  Cans  for  Cloth  and  Warps. 
(Textile-Finishing  Machinery  Co.) 


case  of  silk,  and  in  reeling  and  winding  this  material  it  is  necessary  to 
keep  it  somewhat  moist  in  order  to  have  it  run  properly. 

7.  Action  of  Heat  on  Textile  Fibers. — In  the  various  operations 
of  dyeing  and  finishing  frequently  relatively  high  temperatures  are  em- 
ployed. Of  course,  in  cases  where  the  treatment  is  with  solutions  the  tem- 
perature practically  never  exceeds  212°  F.  (100°  C),  the  boiling  point  of 
water.  But  in  drying,  pressing  and  dry  steaming,  the  fibers  may  come  in 
contact  with  much  higher  temperatures.     Wool  is  rather  easily  injured 


62 


CHEMICAL  STUDY  OF  THE  FIBERS 


when  subjected  for  any  length  of  time  to  a  dry  heat  exceeding  220°  F. 
(105°  C),  a  gradual  decomposition  of  the  fiber  taking  pla,ce,  while  it  soon 
acquires  a  yellow-brown  color,  and  ammoniacal  fumes  are  given  ofif.  At 
temperatures  above  250°  F.  the  decomposition  is  rather  rapid.  Silk  is 
affected  by  high  temperatures  much  in  the  same  manner  as  wool.  Cotton, 
however,  is  more  resistant  and  can  stand  a  prolonged  exposure  to  a 
temperature  which  would  soon  discolor  wool.  At  temperatures  beyond 
250°  F.  (120°  C),  however,  cotton  will  soon  begin  to  show  deterioration, 
and  if  exposed  to  higher  temperatures  a  discoloration  of  the  fiber  will  soon 


Fig.  51. — Crabbing  Machine.     (German  Type.) 


indicate  gradual  decomposition.     All  the  fibers  can  withstand  a  much 
higher  temperature  of  moist  heat  (steam)  than  of  dry  heat. 

In  cases  where  metalUc  salts  (such  as  mordants,  weighting  agents, 
and  fillers)  are  held  in  the  fibers  the  effect  of  heat  is  generally  much  more 
injurious.  Silk,  for  example,  which  is  heavily  weighted  with  tin,  shows 
rapid  deterioration  when  exposed  to  high  temperatures.  In  the  sizing 
and  finishing  of  cotton  goods  magnesium  chloride  or  zinc  chloride  is  fre- 
quently added  to  the  fibers;  as  these  salts  become  strongly  acid  at  high 
temperatures,  the  effect  is  to  weaken  seriously  or  tender  the  cotton.     So 


THE  CRABBING  PROCESS 


63 


under  such  conditions,  exposures  to  too  high  a  temperature  in  drying  or 
finishing  should  be  carefully  avoided. 

Under  the  ordinary  conditions  of  boiling  the  fibers  are  not  injured  by 
the  heat,  but  occasionally  conditions  arise  where  high-pressure  steam  may 
come  in  contact  with  the  goods  in  the  boiling  and  this  may  result  in  damage 
to  the  material.  In  the  kier  boiling  of  cotton,  for  instance,  where  a  closed 
pressure  kier  is  used,  and  the  precaution  has  not  been  taken  to  allow  all 
of  the  air  to  escape,  it  is  possible  to  have  the  highly  heated  steam  come 
in  direct  contact  with  the  goods  not  covered  with  the  solution  owing  to 
displacement  by  the  air,  and  the  result  will  be  burnt  and  tendered  material. 


Fig.  52. — Crabbing  and  Lustering  Machine. 


8.  Action  of  Hot  Water  on  Wool. — When  wool  is  saturated  with 
hot  water  or  moist  steam,  the  fiber  becomes  soft  and  plastic;  that  is  to 
say,  it  can  be  made  to  assume  almost  any  form  by  suitable  pressure. 
If  the  fiber  is  then  cooled  it  becomes  set  in  the  form  thus  given  it  and  will 
continue  to  retain  the  same  in  the  dried  condition.  This  property  of 
wool  (and  other  animal  hair  fibers)  is  made  use  of  in  many  manufactur- 
ing and  finishing  operations  for  the  production  of  certain  effects.  As 
good  examples  may  be  noted  the  formation  of  woolen  (or  fur)  felt  hats 
and  the  production  of  imitation  fur  effects  on  woolen  pile  plushes. 

This  effect  of  hot  water  or  steam  in  making  the  wool  fiber  plastic 
is  also  the  basis  of  the  crabbing  process  for  the  removing  of  creases 
and  wrinkles  in  fabrics  containing  woolen  and  cotton  yarns.     Such  fab- 


64 


CHEMICAL  STUDY  OF  THE  FIBERS 


rics  cockle  up  when  taken  from  the  loom  owing  to  the  difference  in  the 
elasticity  of  the  wool  and  cotton  threads;  the  wool  being  much  more 
curly  and  clastic  will  take  up  or  shrink  more  than  the  cotton  when  the 
loom  tension  is  removed.  The  same  effect  also  takes  place  in  such  goods 
when  scoured  and  finished  owing,  in  this  case,  to  the  more  or  less  degree 
of  felting  together  of  the  wool  fibers,  causing  the  wool  yarn  to  shrink  up 
more  than  the  cotton  and  thus  producing  a  cockled  appearance. 

The  crabbing  operation  consists  in  passing  the  cloth  in  full  width  and 
under  tension  through  boiUng  water,  stretching  and  cooling  and  drying 


Fig.  53. — Hydraulic  Calender.     (German  Type.) 


in  the  stretched  condition.  Or  the  cloth  may  be  wound  up  tightly  on 
perforated  cylinders  and  placed  in  an  apparatus  so  that  steam  maj^  be 
blown  directly  through  the  goods.  This  treatment  is  then  followed  by 
forcing  cold  water  or  cold  air  through  the  cloth.*    By  arranging  the  proc- 

*  Fine  qualities  of  wool  which  must  have  a  soft  and  full  handle  are  crabbed  without 
pressure  and  the  temperature  of  the  water  should  be  only  120  to  140°  F.  But  cloth  of 
very  hard  wool  must  be  crabbed  in  boiling  water  so  that  the  fiber  may  be  sufficiently 
stretched.  Crabbing  with  low  pressure  may  be  satisfactorily  done  by  rolling  on  special 
beams,  but  when  high  pressure  and  tension  arc  used  the  crabbing  machine  must  be 
employed.  After  crabbing  the  pieces  should  be  beamed  on  a  wooden  roller  and  allowed 
to  cool  down,  then  the  pieces  may  be  washed,  either  in  the  rope  form  or  in  full  width. 


THE  DECATIZING  PROCESS 


65 


ess  so  that  the  treatment  with  steam  can  be  given  under  considerable 
pressure,  the  wool  fiber  also  acquires  a  considerable  degree  of  luster.  This 
process  then  becomes  known  as  "  decatizing, "  and  is  extensively  used  on 
all-wool  and  worsted  goods  for  the  production  of  a  high-luster  finish  and 
irrespective  of  any  connection  with  a  crabbing  operation. 

In  the  decatizing  process  the  cloth  is  tightly  wound  on  a  perforated 
beam  which  is  placed  in  a  suitably  constructed  pressure  cylinder  provided 
with  the  requisite  connections.     The  air  is  first  exhausted  from  the  cloth 


Fig.  54. — Apparatus  for  Decatizing. 


by  means  of  a  vacuum,  then  high-pressure  steam  is  forced  through  the 
goods  for  a  brief  time,  followed  by  cold  air  or  cold  water.*     The  lustering 

using  soap  and  soda  or  ammonia  at  90  to  100°  F.  Material  which  is  to  have  a  soft,  full 
handle  is  then  generally  crabbed  once  more,  while  hard  material  (like  cheviots)  has 
to  be  steamed  in  order  to  avoid  cockling  and  to  impart  a  soft  handle  and  fine  luster. 

*  In  the  decatizing  process  a  perforated  iron  or  copper  cylinder  is  used.  This  is 
first  wrapped  with  several  layers  of  cotton  cloth,  then  three  to  six  pieces  are  beamed  on 
this  cylinder  and  enveloped  in  canvas,  the  ends  of  which  are  tied  up  tightly.  Steam  at 
10  to  30  lbs.  pressure  is  then  admitted  through  the  axis  of  the  cylinder  until  it  has  well 
traversed  all  the  layers  of  the  cloth,  which  usually  takes  from  five  to  eight  minutes. 
After  the  first  steaming  the  pieces  are  allowed  to  cool  in  the  beamed  state  (the  cooling 
frequently  being  hastened  by  air  suction),  the  object  of  which  is  to  give  the  goods  a  more 
pronounced  luster.  The  pieces  are  then  drawn  under  tension  on  to  another  perforated 
cylinder  and  steamed  again.  This  is  for  the  purpose  of  making  the  process  more  uni- 
form, as  in  this  manner  the  portions  furthest  from  the  center  where  the  temperature 
is  greatest,  are  brought  nearest  the  center  in  the  second  operation.  After  each  steam- 
ing (especially  when  vertical  rollers  are  employed)  it  is  very  necessary  to  place  the 
rollers  horizontally  on  a  couple  of  supports  and  on  no  account  vertically  or  slanting, 
and  to  turn  the  rollers  every  now  and  then  for  about  half  an  hour  in  order  to  induce  a 
uniform  cooling  action.  It  is  always  advisable  to  steam  the  goods  before  dyeing,  and 
then  after  dyeing  to  steam  again,  but  only  slightly,  as  in  this  way  the  best  results  are 
obtained.     Steaming  before  dyeing  also  has  the  effect  of  producing  more  level  shades. 


66  CHEMICAL  STUDY  OF  THE  FIBERS 

effect  is  doubtless  due  to  the  fact  that  under  the  action  of  the  highly 
heated  steam  the  outer  scaly  portion  of  the  wool  fiber  is  softened  and  as 
the  fiber  is  held  in  a  state  of  tension,  the  surface  tends  to  assume  a  smooth 
rod-like  appearance,  whereby  the  serrations  or  joints  of  the  individual 
scales  become  more  or  less  fused  together.  This  condition  becomes  fixed 
and  permanent  by  the  subsequent  chilling  and  drying  of  the  fiber  still 
maintained  in  its  set  state  of  tension.  This  decatizing  process  is  chiefly 
carried  out  on  close-napped  goods  such  as  broadcloths  and  the  like. 

An  operation  very  similar  to  that  of  decatizing  is  known  as  potting.* 
This  is  a  treatment  of  woolen  goods  with  steam  and  hot  water  for  the 
purpose  of  producing  a  particular  character  of  finish.  It  is  chiefly  used 
on  heavy  suitings  and  broadcloth  and  the  process  and  apparatus  employed 
is  much  the  same  as  in  decatizing. 

9.  Experimental.  Exp.  1.  Action  of  Acids  on  Wool  and  Cotton. — Place  about  300 
cc.  of  water  in  one  of  the  porcelain  beakers  employed  for  the  dye-tests,  and  add  2  cc.  of 
concentrated  sulphuric  acid.  In  this  "  bath  "  boil  a  test  skein  of  woolen  yarn  together 
with  one  of  cotJion  yarn  for  twenty  minutes;  then  remove  the  skeins,  squeeze  out  the 
excess  of  liquid,  and  dry  without  washing.  After  drying  test  the  strength  of  the  two 
skeins,  and  it  will  be  found  that  the  cotton  has  been  very  much  weakened  and  may  be 
easily  pulled  apart,  whereas  the  wool  does  not  appear  to  have  been  much  affected. 
Boil  a  second  set  of  woolen  and  cotton  skeins  in  the  same  acid  bath  for  twenty  minutes, 
then  wash  well  in  several  changes  of  fresh  water.  Take  the  woolen  skein  and,  together 
with  another  one  of  untreated  wool,  dye  by  boiling  for  twenty  minutes  in  a  beaker 
containing  300  cc.  of  water  and  10  cc.  of  Acid  Magenta  solution  (containing  5  grams  of 
the  dissolved  dyestuff  per  liter);   then  wash  well  and  dry.     It  will  be  noticed  that  the 

If  the  steaming  has  not  been  carried  out  properly,  and  especially  when  the  second  steam- 
ing is  omitted  and  vertical  cylinders  have  been  used,  the  pieces  are  liable  to  become 
"ended";  that  is  to  say,  large  patches  unnoticed  before  dyeing  will  show  up.  These 
are  caused  by  uneven  condensation  of  the  steam  in  the  goods.  These  defects  are  indis- 
cernible previous  to  the  dyeing  and  are  usually  attributed  to  the  dyer.  This  is  par- 
ticularly true  in  the  case  of  cheviots  which  often  contain  two  different  kinds  of  yarn, 
such  as  hard  tightly  twisted  worsted  warp  and  a  soft  loose  weft.  Goods  of  this  char- 
acter are  very  much  inclined  to  show  uneven  penetration. 

*  In  the  potting  process  the  pieces  are  wound  on  a  perforated  steam  cylinder  which  is 
placed  within  a  machine  with  a  reversible  driving  gear,  and  through  the  hollow  shaft  of 
the  cylinder  steam  or  water  or  both  can  be  drawn  through  the  goods.  After  washing 
and  brushing  the  goods  are  beamed  on  the  cylinder  in  the  usual  manner  and  inserted 
into  the  potting  machine.  Cold  water  is  first  forced  through  the  goods,  and  then  steam. 
Admission  of  the  steam  to  the  water  takes  place  before  it  enters  the  cylinder  so  that  the 
temperature  of  the  water  is  gradually  increased  and  is  finally  brought  almost  to  boiling. 
The  hot  water  is  thus  pumped  through  for  two  to  three  minutes,  then  the  steam  is 
turned  off,  and  the  goods  are  cooled  down  with  cold  water.  For  broadcloth  which  has 
to  receive  a  fine  gloss  and  a  soft  finish  the  following  process  is  often  used:  Steam  is 
first  forced  through  the  goods  for  fifteen  to  twenty  minutes,  then  the  steam  is  turned 
off  and  water  is  pumped  through.  This  produces  a  fine  gloss.  Next,  hot  water  is 
pumped  through  the  cloth  to  give  a  soft  handle,  then  air  is  sucked  through  and  the  goods 
unrolled. 


EXPERIMENTAL  STUDIES  67 

skein  which  has  been  treated  with  acid  will  be  dj-ed  a  heavier  color  than  the  second  skein. 
This  i?  due  to  the  wool  having  combined  chemically  with  the  acid  in  its  first  treatment, 
thus  allowing  it  to  react  more  readily  with  the  acid  dyestuff  employed.  Take  the  second 
cotton  skein  and  pass  it  through  a  cold  solution  of  1  gram  of  soda  ash  in  300  cc.  of  water 
for  ten  minutes;  then  rinse  in  fresh  water  and  dry.  It  will  be  found  that  this  skein 
has  not  become  weakened  by  the  treatment  with  the  acid  solution,  as  the  latter  has 
been  neutralized  by  the  alkali  before  drj'ing. 

Exp.  2.  Action  of  Organic  Acids  on  Cotton. — Work  a  test  skein  of  cotton  yarn  in  a 
bath  containing  300  cc.  of  water  and  5  cc.  of  acetic  acid  for  twenty  minutes  at  a  tem- 
perature of  160°  F.  Squeeze  and  dry  without  washing.  Test  the  strength  of  the  dried 
skein  and  it  will  be  found  not  to  have  become  much  weakened.  Acetic  acid  is  a  volatile 
organic  acid  and  on  drj'ing  is  volatilized  from  the  fiber. 

Exp.  3.  Action  of  Concentrated  Sulphuric  Acid  on  Cotton. — Place  about  50  cc.  of 
concentrated  sulphuric  acid  in  a  beaker  and  rapidly  pass  through  it  a  small  skein  of 
cotton  yarn,  then  immediately  wash  it  in  a  large  amount  of  water  until  all  of  the  acid  is 
removed.  It  will  be  found  that  the  strong  acid  has  caused  the  fibers  to  swell  and  form  a 
rather  gelatinous  mass.  On  drying  it  will  give  a  parchment-like  substance.  This 
treatment,  in  fact,  is  employed  for  the  preparation  of  vegetable  parchment  pajKT  from 
ordinary  paper.  The  substance  of  the  paper  is  cellulose,  which  is  the  same  as  the 
substance  of  the  cotton  fiber.  Take  a  second  small  skein  of  cotton  yarn  (or  some  loose 
cotton)  and  steep  it  for  some  time  in  the  concentrated  sulphuric  acid.  A  gelatinous 
mass  is  first  formed,  which  soon  dissolves  completely.  If  this  solution  is  carefully 
diluted  with  water  and  boiled  for  some  time,  the  dissolved  cellulose  (which  may  be 
regarded  as  existing  as  cellulose  sulphate)  will  be  converted  into  glucose. 

Exp.  4.  Illustrating  the  Carbonizing  Process. — Take  a  small  piece  of  cloth  contain- 
ing wool  and  cotton  yarns  (known  as  "  union  "  goods,  made  up  with  a  cotton  warp  and  a 
wool  filling)  and  steep  it  in  a  solution  of  100  cc.  of  water  and  2  cc.  of  concentrated 
hydrochloric  acid  until  thoroughly  saturated.  Then  squeeze  and  dry  in  an  oven  at 
220  to  240°  F.  for  two  hours.  The  sample  should  then  be  rubbed  and  beaten  vigorously, 
and  it  will  be  found  that  the  cotton  portion  will  be  easily  broken  up  and  dusted  out, 
leaving  only  the  wool  in  a  practically  pure  condition. 

Exp.  5.  Action  of  Hydrochloric  Acid  on  Silk. — Steep  a  test  skein  of  silk  yarn  in  a 
bath  containing  300  cc.  of  water  and  5  cc.  of  hydrochloric  acid  at  160°  F.  Squeeze  and 
dry  without  washing.  Test  the  strength  of  the  dried  skein  and  notice  that  it  is  some- 
what weakened.  The  tendering  effect  will  become  much  more  apparent  after  the  skein 
has  been  left  for  several  weeks. 

Exp.  6.  Scrooping  Effect  of  Organic  Acids  on  Silk.— Work  a  test  skein  of  silk  yarn 
in  a  bath  containing  300  cc.  of  water  and  5  grams  of  tartaric  acid  for  twenty  minutes 
at  140°  F.  Squeeze  and  dry  without  washing.  Notice  that  the  dried  skein  when 
squeezed  emits  a  pecuhar  crunching  sound.  Also  note  the  increased  luster  of  the  fiber. 
The  latter  will  become  more  apparent  if  the  skein  is  stretched  and  steamed  with  dry 
steam. 

Exp.  7.  Action  of  Alkalies. — Boil  a  skein  of  woolen  yarn  together  with  one  of  cotton 
in  a  bath  containing  300  cc.  of  water  and  10  cc.  of  caustic  soda  solution  (60°  Tw.). 
The  wool  will  be  disintegrated  and  dissolved.  Wash  and  dry  the  cotton  skein  and  it 
will  be  found  not  to  be  appreciably  altered.  Repeat  the  test,  using  10  cc.  of  a  solution 
of  sodium  carbonate  instead  of  caustic  soda.  Boil  for  twenty  minutes,  then  wa.sh  and 
dry.  It  will  be  found  that  the  wool  has  become  much  weakened  and  is  lifeless  and  dull 
in  appearance,  while  the  cotton  is  not  changed.  Repeat  this  test,  using  10  cc.  of  a  solu- 
tion of  ammonium  carbonate;  boil  for  twenty  minuter,  then  wash  and  dry.  It 
will  be  noticed  that  in  this  case  neither  the  wool  nor  the  cotton  is  affected  in 
strength. 


68 


CHEMICAL  STUDY  OF  THE  FIBERS 


Exp.  8.  Mercerization  of  Cotton. — Take  a  piece  of  ordinary  cotton  cloth  (calico) 
measuring  4X4  ins.  in  size,  steep  it  for  a  few  minutes  in  a  cold  solution  of  caustic  soda 
of  55°  Tw.  strength,  then  rinse  well  in  fresh  water  until  the  alkali  is  all  removed,  and 
allow  to  dry.  Now  remeasure  the  sample  and  record  the  amount  of  shrinkage;  also 
note  the  increase  in  strength.  Wind  a  small  skein  of  Sea  Island  2-ply  cotton  yarn 
tightly  on  a  small  iron  frame  (this  may  be  constructed  as  in  Fig.  55) ;  dip  this  into  a  cold 
caustic  soda  solution  as  above  for  five  minutes;  without  removing  from  the  frame  rinse 
in  fresh  water  well,  then  in  water  slightly  acidulated  with  sulphuric  acid  to  neutralize 
all  the  alkali,  and  finally  rinse  in  water  containing  a  little  ammonia  to  avoid  danger 
t)f  leaving  any  excess  of  acid  in  fiber.  Remove  the  yarn  from  the  frame  and  note  the 
increase  in  luster. 

Treat  a  skein  of  cotton  j'arn,  without  stretching,  in  the  caustic  soda  solution  (55° 
Tw.)  cold  for  ten  minutes,  then  wash  well  and  neutralize  with  a  very  dilute  solution  of 
sulphuric  acid.  Cut  the  skein  in  half  and  together  with  a  half  skein  of  ordinary  cotton 
yarn  boil  for  twenty  minutes  in  beaker  of  water  containing  10  cc.  of  Diamine  Blue  solu- 
tion; then  wash  well  and  dry.  It  will  be  found  that  the  skein  treated  with  the  caustic 
soda  takes  on  a  darker  color,  which  shows  that  mercerized  cotton  has  a  greater  affinity 
for  substantive  dyestuffs,  of  which  the  color  given  is  representative.      Boil  the  second 


Fig.  55. — Mercerizing  Test  Frame. 


half  of  the  mercerized  skein  together  with  a  half  skein  of  ordinary  cotton  yarn  for 
twenty  minutes  in  a  beaker  of  water  containing  5  cc.  of  Methylene  Blue  solution,  and 
afterwards  wash  well  and  dry.  It  will  be  found  that  the  "  mercerized  "  skein  becomes 
tinted  to  quite  an  extent  with  the  basic  dye  used,  whereas  the  other  skein  is  scarcely 
tinted  at  all.  Caustic  soda  effects  a  chemical  change  in  the  substance  of  the  cotton 
fiber  which  gives  it  an  increased  affinity  towards  basic  dyes. 

Exp.  9.  Action  of  Metallic  Salts  (Mordants). — Boil  a  skein  of  wool  together  with 
one  of  cotton  for  twenty  minutes  in  a  bath  containing  300  cc.  of  water,  and  10  cc.  of 
chrome  solution.  Rinse  with  fresh  water.  Then  boil  the  woolen  skein  together  with 
another  of  untreated  wool  in  a  bath  containing  300  cc.  of  water  and  20  cc.  of  a  solution 
of  Madder.  Finally  wash  well  and  dry.  It  will  be  found  that  the  untreated  skein 
has  not  become  dyed,  whereas  that  treated  with  the  chrome  has  become  colored.  Take 
the  cotton  skein  which  has  been  treated  with  the  chrome  and  boil  it  also  in  a  solution 
containing  300  cc.  of  water  and  20  cc.  of  Madder  solution,  then  wash  well  and  dry.  It 
will  be  found  that  the  cotton  skein  has  taken  up  but  very  little  dyestuff,  as  this  fiber 
absorbs  but  a  small  amount  of  the  mordant.  Madder  is  a  dye  which  has  no  direct 
affinity  for  the  fibers,  but  it  forms  a  color-lake  with  metallic  salts  such  as  chrome; 
hence  the  unmordantcd  wool  did  not  become  dyed.  Due  to  the  fact  that  wool  has  a 
much  greater  aflinily  for  metallic  salts  than  cotton,  it  will  be  noticed  that  the  former 
fiber  is  dyed  much  (leoi)er  than  the  latter. 

Exp.  10.  Action  of  I.Iotallic  Salts  on  Cotton.— Steep  a  skein  of  cotton  yarn  in  a 
beaker  of  water  containing  5  grams  of  calcium  chloride,  squeeze  and  dry  without  wash- 
ing.    After  drying,  test  the  strength  of  the  skein  and  it  will  be  found  to  have  become 


EXPERIMENTAL  STUDIES  69 

considerably  weakened.  Calcium  chloride  represents  a  salt  of  an  acid  nature  and 
causes  a  decomposition  of  the  cotton  fiber.  Steep  another  skein  of  cotton  yarn  in 
a  beaker  of  water  containing  5  grams  of  sodium  sulphate  (glaubersalt),  squeeze  and  dry 
without  washing.  On  testing  this  skein  it  will  be  found  that  its  strength  is  not  materi- 
ally affected.  This  second  salt  represents  a  neutral  metallic  salt  and  has  little  action  on 
cotton.  Steep  another  skein  in  a  beaker  of  water  containing  5  grams  of  copperas 
(ferrous  sulphate);  squeeze,  and  pass  through  a  second  beaker  of  water  containing  5 
grams  of  soda  ash  dissolved;  then  wash.  It  will  be  found  that  the  skein  has  become 
a  light  buff  color,  due  to  the  fact  that  the  fiber  has  absorbed  from  solution  some  of  the 
iron  salt  which  by  afterwards  coming  in  contact  with  the  alkali  formed  a  precipitate 
of  oxide  of  iron.  On  this  reaction  is  based  the  methods  of  dyeing  cotton  with  the  mineral 
pigments.  Take  this  skein  together  with  one  of  ordinary  cotton,  and  boil  them  in  a 
b(>aker  of  water  containing  1  gram  of  ground  Madder,  and  wash  and  dry.  It  will  be 
found  that  the  skein  containing  the  metallic  salt  will  become  dyed  with  the  Madder, 
while  the  other  skein  will  not.  On  this  reaction  is  based  the  principle  of  mordanting 
cotton  for  the  use  of  certain  dyestuffs  which  require  a  metallic  mordant  to  yield  a  color- 
lake. 

Exp.  11.  Action  of  Zinc  Chloride  Solution  on  Cotton. — Place  about  50  cc.  of  a  con- 
centrated solution  of  zinc  chloride  in  a  beaker  and  add  about  2  grams  of  loose  bleached 
cotton  and  heat.  The  cotton  will  be  found  to  dissolve.  Pour  a  portion  of  the  solution 
into  water,  and  a  precipitate  of  cellulose  will  be  formed.  This  solution  of  cotton  in 
zinc  chloride  solution  is  used  for  the  preparation  of  cellulose  filaments  which  are  car- 
bonized and  used  for  the  filaments  in  incandescent  electric  lamps.  The  use  of  this 
solution  of  cotton  has  also  been  tried  for  the  preparation  of  artificial  silk. 

Exp.  12.  Action  of  Ammoniacal  Solution  of  Copper  Oxide  on  Cotton. — This  solution 
is  a  blue  liquid  prepared  by  dissolving  freshly  precipitated  copper  hydrate  in  ammonia 
water.  Take  about  50  cc.  of  the  solution  in  a  beaker  and  dip  a  piece  of  bleached  calico 
in  the  liquid,  remove  and  dry  without  washing.  It  will  be  found  that  the  cloth  has 
become  coated  with  a  film  of  gelatinized  cellulose  mixed  with  copper  hydroxide,  and  is  of 
a  green  color.  On  this  reaction  is  based  the  preparation  of  the  Willesden  waterproof 
canvas.  Test  the  dried  sample  of  calico  with  water,  and  it  will  be  found  to  be  water- 
proof. Now  add  to  the  ammoniacal  copper  hydrate  solution  about  2  grams  of  bleached 
loose  cotton  and  stir  well.  The  cotton  will  soon  dissolve.  Pour  a  portion  of  the  solu- 
tion into  water  and  a  precipitate  of  cellulose  will  separate  out.  This  solution  of  cotton 
is  employed  for  the  preparation  of  artificial  silk. 

Exp.  13.  Action  of  Bleaching  Powder. — Steep  a  skein  of  woolen  yarn  together  with 
one  of  cotton  in  a  cold  solution  of  bleaching  powder  of  about  2°  Tw.  strength  for  thirty 
minutes.  Then  pass  into  a  cold  bath  containing  300  cc.  of  water  and  10  cc.  of  a  dilute 
solution  of  hydrochloric  acid  (the  odor  of  what  gas  is  noticed  here?)  and  work  for  ten 
minutes.  Then  wash  well  in  fresh  water.  It  will  be  found  that  the  cotton  has  become 
bleached,  but  that  the  wool  has  acquired  a  deeper  yellow  tint  and  is  harsh  in  feel  after 
drying.  The  wool  has  combined  with  the  chlorine  of  the  bleaching  powder  in  a  chemical 
manner  while  the  cotton  has  not;  the  only  effect  in  the  latter  case  being  that  the  bleach- 
ing liquor  destroys  the  coloring  matter  naturally  present  in  the  cotton.  Next,  take 
this  skein  of  "  chlorinated  "  wool  together  with  a  skein  of  untreated  wool  and  dye  them 
for  twenty  minutes  at  160°  F.  in  a  bath  containing  300  cc.  of  water  and  5  cc.  of  a  solu- 
tion of  Diamine  Sky  Blue;  wash  and  dry.  It  will  be  found  that  the  "  chlorinated  " 
skein  takes  up  much  more  dyestuff  than  the  other  skein  and  is  dyed  a  darker  shade. 
Next,  take  portions  of  these  two  skeins  and  plait  them  together  and  steep  in  a  small 
quantity  of  warm  soap  solution  and  rub  vigorously  between  the  hands  to  imitate  the 
action  of  fulling  or  milling.  It  will  be  found  that  the  ordinary  wool  will  readily  felt 
together,  while  the  chlorinated  wool  does  not. 


70  CHEMICAL  STUDY  OF  THE  FIBERS 

Exp.  14.  Action  of  Oxidizing  Agents  on  Cotton. — Take  a  strip  of  calico  and  spot  it 
in  several  places  with  a  paste  made  from  some  chloride  of  lime  and  a  little  water.  Allow 
to  remain  for  one-half  hour  then  wash  off  the  paste  with  water  acidulated  with  hydro- 
chloric acid,  and  then  wash  with  water  made  slightly  alkaline  with  ammonia.  Next 
boil  the  strip  of  calico  in  a  beaker  of  water  containing  1  cc.  of  Methyler'^  Blue  solution 
(a  basic  dyestulT),  then  wash  and  dry.  It  will  be  found  that  where  the  cloth  was  spotted 
with  the  chloride  of  lime  the  color  is  taken  up  to  a  considerable  extent,  whereas  the  rest 
of  the  calico  is  scarcely  tinted.  The  chloride  of  lime  has  caused  an  oxidatioii  of  the 
cotton  with  the  formation  of  oxycellulose,  and  this  substance  has  a  much  stronger 
affinity  for  basic  dyes  than  ordinary  cotton.  Cut  a  portion  of  the  strip  off  so  as  to  include 
one  of  the  spots,  and  test  its  strength;  it  will  be  found  that  the  oxidation  of  the  fiber 
has  caused  a  considerable  tendering  in  strength.  Take  a  second  similar  strip  of  calico 
and  spot  it  in  the  same  manner  with  a  mixture  of  potassium  bichromate  and  sulphuric 
acid,  and  after  standing  for  one-quarter  hour,  wash  it  off  with  water,  and  finally  with 
water  slightly  alkaline  with  ammonia.  Then  treat  it  in  the  same  manner  as  above 
with  the  solution  of  Methylene  Blue,  and  also  test  the  strength  of  the  fiber.  This  mix- 
ture of  chrome  and  acid  is  a  strong  oxidizing  agent  and  also  converts  cotton  into  oxy- 
ellulose. 

Exp.  15.  Moisture  in  Textile  Fibers. — Take  a  test  skein  of  woolen  yarn,  weigh  it 
accurately;  heat  in  an  oven  for  two  hours  at  220°  F.,  then  quickly  reweigh,  and  calculate 
the  percentage  of  loss  as  moisture.  Care  should  be  taken  not  to  allow  the  temperature 
to  go  over  220°  F.  as  the  wool  would  otherwise  be  injured.  Now  expose  the  skein  to  the 
air  for  several  hours  (or  overnight),  and  reweigh.  Calculate  the  percentage  of  regain 
on  the  dry  weight  of  the  wool.  Note  if  the  dried  wool  returns  to  its  original  weight. 
Repeat  these  tests,  using  a  skein  of  cotton  and  also  one  of  silk.  Note  the  different  per- 
centages of  moisture  in  each  case,  and  also  the  percentage  of  regain. 

Exp.  16.  Effect  of  High  Temperatures. — Heat  a  skein  of  wool  in  an  oven  at  a  tem- 
perature of  225°  F.  for  one  hour,  and  then  observe  if  any  discoloration  is  evident  and  if 
the  fiber  is  weakened.  Then  raise  the  temperature  to  250°  F.  for  one  hour  longer  and 
note  the  effects  produced.  Also  subject  a  skein  of  cotton  and  one  of  silk  to  the  same 
conditions  and  note  the  effects  produced  in  both  cases. 


CHAPTER   II 

SCOURING  THE  TEXTILE  FIBERS 

1.  Impurities  in  Raw  Wool. — The  raw  wool  fiber  as  it  exists  in  the  fieece 
contains  a  large  amount  of  natural  impurities.     These  are  as  follows: 

a.  Grease,  or  wool-fat. 

h.  Suint,  or  dried-up  perspiration. 

c.  Dirt,  consisting  of  dust,  sand,  burrs,  etc. 

It  is  the  object  of  scouring  to  remove  these  impurities  and  leave  the  fiber 
pure  and  clean  without  material  injurj^  to  its  good  qualities.  The  greasy 
matters  in  the  fleece,  known  as  wool-fat,  are  insoluble  in  water,  but  are 
readily  emulsified  by  solutions  of  soaps  or  alkalies.  Wool-fat  differs  from 
most  other  animal  fats  in  chemical  constitution  in  that  the  latter  are  com- 
pounds of  various  fatty  acids  with  glycerin  (and  hence  are  called  glycerides). 
These  rather  easily  react  with  caustic  alkalies  to  form  soluble  soaps,  a  reac- 
tion which  is  termed  saponification.  Wool-fat,  however,  is  not  a  glj'-ceride, 
but  contains  a  substance  known  as  cholesterol  (a  body  belonging  to  the 
general  class  of  alcohols)  and  does  not  form  soaps  with  the  caustic  alkalies. 
It  does,  however,  form  emulsions  with  more  ease  than  do  the  other  animal 
fats,  and  on  this  account  it  is  rather  easily  removed  from  the  fiber.  The 
suint  (a  French  word  for  sweat)  consists  of  various  metallic  salts  of  organic 
acids,  such,  for  instance,  as  potassium  acetate.  These  salts  are  soluble  in 
water  and  hence  are  easily  removed  in  the  scouring.  The  miscellaneous 
dirt  in  the  wool  is  not  soluble  in  water  and  is  simply  mechanically  removed 
by  the  agitation  of  the  wool  in  the  process  of  scouring. 

The  amount  of  impurities  in  raw  wool  varies  quite  largely  with  the 
character  of  the  sheep  and  the  locality  in  which  they  are  grown.  Gener- 
ally speaking,  the  total  impurities  may  be  said  to  vary  from  50  to  80  per 
cent  of  the  weight  of  the  fleece,  with  a  general  average  of  about  65  per  cent. 
As  a  rule,  the  finer  the  staple  of  the  wool,  the  greater  amount  of  grease  it 
will  contain,  whereas  in  coarse  wools  the  amount  of  grease  is  usually  rela- 
tively much  less.  The  loss  in  weight  that  wool  undergoes  on  scouring  is 
termed  its  shrinkage,  and  forms  an  important  item  in  judging  the  value  of 
raw  wools. 

7X 


72 


SCOURING  THE  TEXTILE  FIBERS 


The  chemicals  chiefly  employed  in  the  usual  methoil  of  scouring  wool 
are  soda  ash  (sodium  carbonate)  and  soaps.  Potash  (potassium  carlion- 
ate)  is  sometimes  used,  but  as  it  is  much  more  expensive  than  soda  ash  its 
use  is  more  restricted.  Most  frequently  a  mixture  of  soda  ash  and  soap 
is  used,  the  relative  amounts  depending  on  the  quality  of  the  wool  to  be 
scoured  and  the  amount  and  nature  of  the  impurities  present.  As  the  wool 
fiber  is  rapidly  injured  by  solutions  of  alkalies  at  high  temperatures,  the 
scouring  of  wool  should  be  carried  out  at  as  low  a  temperature  as  per- 
missible with  perfect  removal  of  the  impurities. 

The  temperature  of  the  scouring  bath  under  ordinary  conditions 
should  not  exceed  140°  F.,  and  in  the  case  of  fine  luster-wools  the  lower 
temperature  of  100  to  120°  F.  is  used.  Attention  has  already  been  drawn 
to  the  fact  that  wool  is  easily  injured  by  even  quite  dilute  solutions  of 
caustic  alkalies,  consequently  the  presence  of  such  is  especially  deleterious. 
On  this  account,  the  soaps  and  other  ingredients  used  in  the  scouring  solu- 


"FiG.  56.— Wool  Washer.     (C.  G.  Sargent's  Sons.) 


tions  should  be  free  from  any  very  appreciable  amount  of  caustic 
alkali. 

After  removal  from  the  soap  solution,  the  scoured  wool  should  be  thor- 
oughly cleansed  from  alkali  and  soap  b}^  washing  in  water.  If  this  is  not 
done  the  soap  will  dry  into  the  fiber,  and  subsequently  be  very  difficult 
to  remove  properly.  The  presence  of  soapy  matters  in  the  wool  leads  to 
many  l)ad  effects;  it  causes  the  product  to  have  a  sticky  and  greasy  feel, 
produces  unevenness  in  dyeing,  and  when  brought  into  an  acid  solution 
(as  is  generally  the  case  in  the  application  of  most  dyestufTs  to  wool), 
the  soap  is  decomposed  with  the  liberation  of  free  fatty  matter  in  the 
fiber,  which  is  a  very  objectionable  result. 

2.  The  Emulsion  Process  of  Scouring. — The  ordinary  process  of  scour- 
ing wool  by  the  use  of  solutions  of  soaps  and  alkalies  is  called  an  "  emul- 
sion "  process  on  account  of  the  fact  that  the  soapy  and  alkaline  liquors 
form  an  emulsion  with  the  greasy  matters  in  the  wool.  A  distinction  must 
be  made  between  an  emulsion  and  a  solution.  An  emulsion  is  an  intimate 
mixture  of  greasy  or  oily  matters  with  water  (or  solution  of  soap  or  alkah) 
in  which  the  grease  exists  disseminated  throughout  the  mixture  in  a  very 


CHARACTER  OF  EMULSIONS 


73 


finely  divided  state,  usually  in  the  form  of  minute  globules.  The  emul- 
sion is  considered  as  permanent  when  the  greasy  matters  do  not  readily 
separate  from  the  liquid  in  a  distinct  layer.     In  a  solution,  on  the  other 


Fig.  57. — Wool-washing  Machiae.     (English  Type.) 


FxG.  58. — Wool-scouring  Machine.     (Oval  Type.) 

hand,  the  dissolved  substance  is  not  merely  broken  up  into  small  particles 
and  held  in  suspension,  but  its  identity  becomes  merged  with  that  of  the 
liquid  solvent.  It  is  to  be  noted  that  the  greasy  matters  of  the  wool  do 
not  actually  pass  into  solution  but  remain  finely  suspended  as  an  emulsion. 


74  SCOURING  THE  TEXTILE  FIBERS 

and  in  consequence  of  this  may  be  separated  from  the  scouring  hquor  ];y 
suitable  mechanical  treatment.  The  suint,  on  the  other  hand,  passes  into 
solution. 

3.  Use  of  Alkali  in  Scouring.— In  adjusting  the  amount  of  alkali 
(soda  ash)  to  be  used  in  scouring,  reference  must  be  had  to  the  quality 
and  quantity  of  impurity  in  the  wool,  and  also  to  the  quality  of  the  fiber. 
An  excessive  amount  of  alkali  must  be  guarded  against,  as  it  is  liable  to 
injure  the  luster  and  strength  of  the  fiber,  and  also  tends  to  discolor  it. 
The  finer  the  quality  of  the  fiber,  as  a  rule,  the  less  the  amount  of  alkali 
that  should  be  employed,  and  this  is  especially  true  of  luster-wools  and 
fine  merinos.  Coarser  and  lower  grade  wools  are  scoured  with  a  relatively 
larger  amount  of  alkali.  It  is  a  mistake  to  presume  that  the  more  dirty 
and'greasy  the  wool,  the  more  alkaline  should  be  the  scouring  liquors;  this 
may  be  true  when  reference  is  had  to  wools  of  about  the  same  quality,  but  a 
very  dirty  and  greasy  fine  merino  wool  should  be  scoured  with  less  alkali 
than  a  comparatively  clean  but  low-grade  Territory  wool,  on  account  of 
the  greater  hability  to  injure  the  fiber  in  the  former  case. 

4.  Carbonizing. — A  great  amount  of  the  raw  wool  coming  into  trade 
(especially  that  from  South  American  countries)  is  contaminated  with 
vegetable  substances  such  as  burrs,  spike-grass,  etc.  These  are  usually 
not  completely  removed  by  scouring  or  by  the  mechanical  processes 
through  which  the  wool  subsequently  passes,  with  the  result  that  these 
vegetable  fibers  continue  to  be  present  even  in  the  finished  cloth  or  fabric. 
This  causes  specky  dyeing,  for,  as  a  rule,  the  vegetable  fiber  is  not  dyed  by 
the  coloring  matters  employed  for  the  dyeing  of  the  wool.  Also  the  pres- 
ence of  the  vegetable  material  considerably  lowers  ths  quality  of  the  fin- 
ished goods. 

In  order  to  clear  the  wool  of  these  vegetable  impurities  the  process 
known  as  "  carbonizing  "  is  resorted  to.  This  process  depends  on  the 
difference  in  the  action  of  acids  on  wool  and  vegetable  tissue  (such  as 
pointed  out  on  page  66).  If  dilute  solutions  of  acids  are  allowed  to  dry 
into  wool,  the  wool  is  not  materially  affected  or  weakened;  but  cotton,  or 
other  vegetable  fiber,  under  such  conditions  becomes  totally  destroyed 
and  reduced  to  a  friable  powder  which  may  easily  be  removed  by  beating 
and  washing. 

There  are  several  methods  of  carbonizing,  and  the  process  selected  will 
depend  on  the  character  of  the  goods  and  the  circumstances  of  the  partic- 
ular case.  Treatment  with  dilute  solutions  of  sulphuric  acid  and  subse- 
quent drying  is  the  principal  and  favorite  method  of  carbonizing.  The 
material  to  be  treated  is  impregnated  with  a  solution  of  sulphuric  acid  * 
of  2  to  6°  Tw.  (2  to  5  per  cent  strength)  at  a  temperature  of  210  to  212° 

*  This  treatment  must  be  carried  out  in  wooden,  cement,  or  better  j^et,  lead-lined 
vats;  and  care  must  be  had  to  avoid  iron  fittings  or  iron  spots  may  get  on  the  goods. 


CARBONIZING  PROCESS  75 

F.  The  goods  are  then  squeezed  or  hydro-extracted  *  and  dried  first  at  a 
temperature  of  about  140  to  160°  F.,  then  the  temperature  is  raised  for  a 
while  to  220°  F.  in  order  to  complete  the  decomposition  of  the  vegetable 
matter. 

Instead  of  using  sulphuric  acid  the  goods  to  be  carbonized  may  be 
subjected  to  the  action  of  moist  hydrochloric  acid  gas.  This  process  is 
generally  employed  for  carbonizing  woven  cloth,  as  it  may  be  used  as  a 
continuous  operation.  The  cloth,  in  a  slightly  moist  condition,  is  passed 
through  the  carbonizing  chamber,  where  it  is  acted  on  by  the  hydro- 
chloric acid  gas  at  a  temperature  of  210  to  230°  F.  It  then  passes  through 
a  beating  operation  and  is  finally  washed  to  remove  the  decomposed  and 
disintegrated  vegetable  matter. 

Solutions  of  aluminium  chloride  have  also  been  used  for  purposes  of 
carbonizing  woolen  fabrics,  the  goods  being  saturated  with  a  dilute  solu- 
tion of  this  salt  and  then  dried.  Aluminium  chloride  is  a  salt  which  is 
easily  hydrolyzed,  especially  when  heated,  with  the  liberation  of  hydro- 
chloric acid  in  situ,  and  this  latter  affects  the  carbonization  of  the  vegetable 
matter. 

Loose  wool  is  carbonized,  of  course,  after  scouring,  as  the  treatment 
would  not  be  practicable  on  the  raw  greasy  wool.  Carbonizing  of  loose 
wool  is  usually  necessary  when  dealing  with  low-grade  burry  wools.  The 
sulphuric  acid  treatment  is  mostly  employed  as  indicated  above.  The 
drying  is  usually  carried  out  in  special  drying  machines  so  constructed  as 
to  withstand  the  action  of  the  acid,  or  the  treated  wool  is  spread  out  on 
racks  and  dried  in  a  hot  room.  The  heat  employed  in  either  case  should 
not  go  over  220°  F.  After  drying  the  wool  is  passed  through  a  form  of 
"  willow  "  or  "  wolf  "  suitable  for  the  disintegration  of  the  decomposed 
vegetable  matter.  A  washing  operation  is  generally  necessary  after  this, 
for  though  the  broken-up  vegetable  tissue  is  easily  removed  and  dusted 
out  by  the  various  mechanical  operations  through  which  the  wool  passes 
in  carding  and  spinning,  nevertheless  it  is  well  to  neutralize  the  wool  by 
washing  in  a  solution  of  soda  ash,  of  3  to  6°  Tw.  at  140°  F.  and  then 
rinsing.  If  this  is  not  done  trouble  is  liable  to  be  experienced  in  the  sub- 
sequent dyeing  of  the  wool. 

5.  The  Scouring  of  Woolen  Yarn. — As  the  impurities  in  woolen  yarn 
differ  very  materially  from  those  present  in  raw  wool,  we  would  naturally 
expect  a  difference  in  the  manner  of  scouring.  The  impurities  in  yarn,  in 
the  first  place,  are  much  less  in  amount,  varying  from  10  to  20  per  cent  in 
ordinary  woolen  yarns,  and  from  2  to  5  per  cent  with  most  worsted  yarns. 
The  character  of  these  impurities  is  also  different;  they  consist  of  the  oil 
which  has  been  added  during  the  spinning  of  the  wool,  together  with  the 

*  The  centrifugal  hydro-extractor  used  for  this  purpose  should  be  specially  lined 
with  lead  or  enamel,  so  that  it  may  resist  the  corroding  action  of  the  acid. 


76 


SCOURING  THE  TEXTILE  FIBERS 


miscellaneous  dust  and  dirt,  it  may  have  collected  passing  through  the 
various  machines  in  carding  and  spinning.  Oil  is  added  to  wool  for  spin- 
ning in  order  to  make  the  fibers  more  plastic  and  to  preserve  them  from 
mechanical  injurj'.  Such  oil  should  be  capable  of  easy  removal  from  the 
spun  yarn  and  should  not  add  any  deleterious  substance  to  the  wool. 
For  instance,  the  oil  should  not  be  of  a  drj-ing  character,  as  it  will  form 
resinous  products  in  the  wool,  the  presence  of  which  would  be  verA^  disad- 
vantageous; further,  the  oil  should  be  capable  of  ready  emulsion  so  that 
no  difficulty  may  be  experienced  in  scouring  the  yarn.  Again,  the  oil 
should  be  free  from  acidity,  as  otherwise  it  would  attack  the  card  clothing 


i'^??xmiKm.>j!m«r*S!x 


Fig.  59. — Yarn  Scouring  Machine.     (Ivlauder-Weldon  Dj-e.  Machine  Co.) 


and  other  metallic  surfaces  with  which  the  wool  maj'  come  in  contact, 
not  only  causing  injurj^  to  the  machines,  but  also  causing  the  wool  to  become 
impregnated  with  iron  compounds,  which  leads  to  many  defects  in  subse- 
quent scouring,  bleaching,  and  dyeing.  Owing  to  the  fact  that  the  impuri- 
ties in  yarn  are  of  less  amount  and  also  more  easily  removed,  it  is  cus- 
tomary to  employ  relatively  less  alkali  in  scouring  than  is  the  case  with 
raw  wool.  Whereas,  in  scouring  the  latter  su])stance  the  proportion  of 
alkali  is  greater  than  that  of  soap,  with  yarn  scouring  the  proportion  is 
just  reversed,  and  more  soap  than  alkali  is  used;  and  furthermore  the 
strength  of  the  scouring  liquors  is  much  diminished.  The  exact  composi- 
tion of  the  scouring  bath,  also,  in  the  case  of  yarn,  must  be  regulated  with 


SCOURING  WOOLEN  YARNS 


77 


reference  to  the  amount  of  impurities  in  the  fiber  as  well  as  the  quality  of 
the  fiber  itself.  Worsted  (and  high-class  yarns  in  general)  containing  but 
little  oil  and  dirt  arc  scoured  in  comparatively  weak  solutions  containing 
a  good  quality  soap  and  a  minimum  amount  of  alkali  (or  in  some  cases 
none  at  all).  With  lower  grade  and  dirtier  woolen  yarns  the  proportion  of 
alkali  is  increased.  The  temperature  of  the  scouring  bath  for  yarn,  as 
with  that  for  raw  wool,  is  generally  about  140°  F.,  though  with  fine  luster- 
wools  even  this  temperature  is  considerably  reduced.  Occasionally, 
with  very  low-grade  yarns,  such  as  coarse  carpet  yarns  (containing  a 


Fig.  60. — Yarn  Scouring  Machine,  showing  Apron  and  Mechanism. 
(Klauder-Weldon  Dye.  Machine  Co.) 


variety  of  crude  hair  fibers,  such  as  goat  and  cow  hair,  coarse  camel  hair, 
mixed  with  jute  and  other  vegetable  fibers,  as  well  as  large  quantities  of 
inferior  grease  used  in  spinning),  the  temperature  of  the  scouring  liquor 
may  be  much  increased,  in  some  cases  even  as  high  as  the  boiling  point. 

The  composition  of  the  wool  oil  employed  in  the  spinning  of  the  yarn 
will  have  much  to  do  with  the  proper  composition  of  the  scouring  liquors. 
In  the  case  of  worsteds  and  high-class  yarns  it  is  customary  to  use  only 
vegetable  or  animal  oils  in  oiling  the  stock;  but  in  the  case  of  low-grade 
yarns,  such  as  shoddies  and  carpet  yarns,  there  is  usually  incorporated  in 
the  wool  oil  a  greater  or  less  proportion  of  mineral  oil.     The  latter  differs 


78 


SCOURING  THE  TEXTILE  FIBERS 


from  the  other  oils  mentioned  above  in  not  being  saponifiable,  nor  is  it  as 
readily  emulsifiable.  Where  mineral  oils  are  used  it  is  necessary,  as  a 
rule,  to  employ  a  higher  percentage  of  soap  in  scouring,  as  the  oil  is  more 


Fig.  61. — Double  Bowi  Yarn  Scouring  Machine. 

easily  emulsified  with  soap  than  it  is  with  alkali.     To  remove  all  of  the 
mineral  oil  it  is  sometimes  necessary  to  repeat  the  scouring  oi:)eration. 

Woolen  and  worsted  yarns  are  usually  scoured  by  hand  by  hanging 
from  sticks  in  a  rectangular  wooden  tank  containing  the  scouring  liquor. 


Fig.  62. — Yarn  Scouring  Machine.     (German  Type.) 


Several  forms  of  machines  have  also  been  devised  in  order  to  economize 
hand  lal)or.  These  are  usually  of  two  types:  (a)  consisting  of  a  revolving 
spider  or  frame  containing  the  sticks  on  which  the  yarn  is  held  and  syste- 
matically turned  while  passing  through  a  semi-cylindrical  tub  containing 


MACHINES  FOR  SCOURING  YARN 


79 


the  scouring  liquor;*  and  (b)  consisting  of  a  traveling  apron  of  wooden 
slats  which  carries  the  yarn  (headed  up  in  bundles)  through  the  soap 
liquor  and  thence  through  squeeze  rolls  (so-called  "  nips  ").     Several  pas- 


FiG.  63. — Scouring  and  Washing  Machine  for  Yam. 


Fig.  64. — Hank  Yarn  Washing  Machine. 


sages  through  such  a  machine  are  generally  required  to  effect  a  perfect 
scouring,  depending  upon  how  dirty  or  oily  the  yarn  may  be. 

*  This  is  the  same  character  of  machine  used  for  dyeing  skein  yarn  hke  the  Klauder- 
Weldon  apparatus  shown  in  Fig.  141  on  page 


80  SCOURING  THE  TEXTILE  FIBERS 

6.  The  Scouring  of  Yams  Containing  Iron. — In  some  cases  woolen  yams 
are  liable  to  contain  quite  api:)rccial)lc  quantities  of  iron,  which  maj^  have 
been  derived  in  a  variety  of  ways,  such  as  rusty  cards,  the  use  of  an  acid 
oil  in  spinning,  contamination  with  the  lubricating  oil  on  the  machines, 
etc.  Such  yarns  are  usually  of  a  deep  grayish  color,  and  if  scoured  in 
solutions  containing  soda  ash  (or  potash)  will  usually  come  from  the 
scouring  bath  badly  discolored  by  a  yellowish  brown  stain.  This  is  due 
to  the  iron  becoming  fixed  in  the  fiber  in  the  form  of  iron  oxide  (iron  rust) 


« 

^ 

.:^  i 

M 

.      ____<   ,:■  ^.™.,--™. .  ^  r    ,X}y: 

I 

'  -^     ft' 

1^                                                                       ^|«H!S»SR'*       ■ 

L    ~"""~"                            '     ■"T(n    '           I.I      1       -■'"'""^ 

1 

Fig.  65.— Dolly  Washer.     (Textile-Finishing  Machinery  Co.) 

by  reaction  with  the  alkali.  Such  yarn  will  exhibit  serious  defects  in  sub- 
sequent dyeing,  as  the  iron  will  act  as  a  "  mordant  "  for  many  coloring 
matters  and  tend  to  dull  or  "  sadden  "  the  color.  Yarn  of  this  character 
should  be  scoured  in  solutions  containing  only  soap  without  the  addition 
of  any  alkali,  so  as  to  permit  of  the  proper  removal  of  the  iron  rather  than 
its  fixation  in  the  fiber. 

7.  Scouring  Tops. — Wool  is  sometimes  scoured  and  dyed  in  the  form  of 
toys  (an  intermediate  stage  between  the  combed  wool  and  the  spun  yarn, 
consisting  of  a  loosely  coherent  rope  of  fibers  with  very^  little  or  no  twist). 


METHOD  OF  SCOURING  TOPS 


81 


As  tops  are  used  for  spinning  into  worsted  yarns,  they  contain  but  little  oil, 
and  this  generally  of  a  good  quality  and  free  from  mineral  oil;  also  tops 


Fig.  66. — Piece  Scouring  Machine. 

are  very  clean  in  their  general  character.  It  is  usual  to  scour  tops  witli 
ammonia  salts  or  with  weak  soap  solutions.  Owing  to  the  delicacy  of 
their  structure,  tops  cannot  be  handled  in  the  same  manner  as  yarn  or 


Fig.  67. — Washer  for  Piece-Goods. 

loose  stock,  but  must  be  scoured  (and  also  dyed)  in  special  machines  with  a 
view  to  disturbing  the  fiber  as  little  as  possible.     Attempts  have  been  made 


82 


SCOURING  THE  TEXTILE  FIBERS 


to  make  the  tops  up  in  the  form  of  large  skeins  and  then  to  process  them 
somewhat  after  the  manner  of  skein  yarn,  using  either  hand  sticks  or  sticks 
in  machines  with  revolving  spiders.     Such  treatment,  however,  causes 


Fig.  68. — Open  Washer  far  Piece-Goods.     (Textile-Finishing  Machinery  Co.) 

much  breakage  of  the  tops  and  also  pulls  them  out  and  causes  distortion. 
Tops  have  been  successfully  scoured  and  dyed,  however,  in  machines 
involving  the  pack  system,  whei'e  the  tops  arc  either  packed  into  suitable 
compartments  through  which  the  liquors  are  circulated,  or  wound  on  large 


Fui.  69.— Four  Comimrtment  Open  Soaper.     (Textile-Fiuisliing  Machinery  Co.) 


perforated  spools  through  which  the  liquors  are  circulated  by  pumping  or 
by  suction. 

8.  Scouring  Woolen  Piece-Goods. — A  large  amount  of  woolen  material 
is  dyed  in  the  form  of  the  woven  piece,  and  this  generally  requires  to  be 


WASHING   MACHINERY 


83 


Fig.  70. — Washer  for  Piece-Goods.     (Dehaitre.) 


84 


SCOURING  THE  TEXTILE  FIBERS 


scoured  before  dyeing.  Even  if  not  dyed,  the  piece  of  goods  coming  from 
the  loom  nearly  always  requires  a  more  or  less  thorough  scouring  operation 
before  it  can  be  finished  and  marketed.     Since  piece-goods    are  mostly 


Fig.  71. — String  Tub  Washer. 


Fig.  72.— Cloth  Washer.     (Rodney  Hunt  Machine  Co.; 

woven  from  unscoured  yarns  they  will  naturally  contain  the  oils  and  other 
impurities  present  in  these  together  with  additional  grease  and  miscella- 
neous dirt  acquired  through  the  various  manufacturing  processes  leading 


SCOURING  WOOLEN  CLOTH 


85 


up  to  and  including  the  weaving.    Furthermore,  the  warp  yarns  are  nearly 
always  sized  so  as  to  give  them  greater  strength  and  smoothness  in  order 


Fig.  73.— Open  Width  Cloth  Washer. 


better  to  resist  the  strain  weaving  and  the  abrasive  action  of  the  rapidly 
moving  shuttle.  The  size  usually  consists  of  starch  and  vegetable  gums 
with  sometimes  added  waxes  or  fats. 
All  of  this  material,  of  course,  has 
to  be  removed  in  the  scouring  and 
washing  operations.  In  the  case  of 
low-grade  shoddy  yarns  of  short 
stapled  fiber,  even  the  filling  is  some- 
times sized  on  the  cops  in  order  to 
furnish  added  strength  in  the  weaving. 
The  same  general  principles  apply 
to  the  scouring  of  pieces  as  to  that 
of  yarns,  the  chief  difference  being  in 
the  method  of  handling  the  material. 
There  are  three  general  types  of  ap- 
paratus in  use  for  this  purpose:  (a) 
A  simple  tub  with  a  revolving  winch 
to  keep  the  cloth  in  motion; 
(h)  a  continuous  string-tub  machine 
through  which  the  cloth  passes  in  rope 

form,  entering  at  one  side  of  the  machine  and  passing  out  at  the  other; 
(c)  an  open-width  machine  in  which  the  cloth  is  maintained  stretched 


Fig.  74. — Fulling  Machine.     (Rodney 

Hunt  Machine  Co.) 


86 


SCOURING  THE  TEXTILE  FIBERS 


out  in  the  open  width.  The  latter  form  of  machine,  however,  is  only  used 
for  rather  special  purposes,  the  one  almost  universally  employed  for  this 
class  of  work  being  the  string  washer.  In  scouring  and  washing  woolen 
piece-goods  care  must  be  had  to  conduct  the  operations  so  as  to  avoid 
felting  as  far  as  possible;  that  is  to  say,  where  a  simple  cleaning  of  the 
material  is  the  end  in  view.  Where  the  scouring  process  is  also  used  as 
one  of  the  finishing  operations,  it  is  frequently  required  to  have  a  certain 
degree  of  felting  (or  "  fulling  "  as  it  is  called),  so  as  to  give  the  fabric  a 
fuller  body  and  bring  the  yarns  closer  up  to  one  another.  In  the  case 
of  worsted  fabrics  this  fulling  is  carried  to  only  a  sUght  degree,  but  in  the 


Fig.  75. — Showing  Action  in  Fulling  Mill. 


ease  of  many  fabrics  of  woolen  yarns,  the  felting  action  required  is  much 
more  pronounced.  These  operations,  however,  relate  more  specifically 
to  the  province  of  finishing,  and  their  more  detailed  consideration  would 
be  out  of  place  at  this  point. 

Woven  fabrics  are  often  made  up  of  variously  colored  yarns  together 
with  those  that  are  undyed.  In  the  scouring  of  such  goods  special  pre- 
cautions must  be  taken  in  order  to  prevent  undue  bleeding  of  the  colors. 
Of  course,  in  such  cases  it  is  essential  that  colors  should  be  used  having  a 
suitable  fastness  to  washing.  It  is  generally  necessary  to  avoid  the  use  of 
alkali  as  far  as  possible;  frequently  a  mild  ammonia  (or  ammonium  car- 
bonate) bath  will  serve  the  purpose  of  scouring. 

In  dealing  with  woolen  or  worsted  pieces  woven  on  a  cotton  warp  it 
will  be  found  on  scouring  that  the  cloth  will  cockle  or  wrinkle  up  owing  to 


PROPERTIES  OF  SCOURING  SOAPS 


87 


the  uneven  contraction  of  the  cotton  and  woolen  yarns.  In  order  to  elim- 
inate the  defect  the  cloth  must  be  crabbed,  an  operation  in  which  the  piece 
is  subjected  to  the  action  of  steam  or  boiling  water  and  then  cooled  quickly 
in  a  stretched  condition.  This  has  the  effect  of  rendering  the  wool  fibers 
more  plastic  so  they  can  be  "  set  "  in  such  a  condition  that  the  wool  yarns 
will  have  the  same  length  as  the  cotton  yarns  (see  page  63). 

9.  Soaps  for  Scouring  Wool. — A  soap  is  a  combination  between  an 
alkali  and  a  fatty  acid,  and  is  produced  by  the  action  of  a  caustic  alkali 
on  an  oil  or  fat.  The  latter  substances  (whether  of  vegetable  or  animal 
origin)   are  compounds  of  glycerin  with   various   fatty   acids,   and   by 


Fig.  76. — Crabbing  Machine  for  Cloth.     (Rodney  Hunt  Machine  Co.) 


proper  treatment  with  caustic  soda  or  caustic  potash  are  decomposed  with 
the  liberation  of  glycerin  and  the  formation  of  a  soap.  Caustic  soda 
yields  hard  soaps,  whereas  caustic  potash  gives  soft  soaps.  The  different 
oils  and  fats,  naturally,  furnish  soaps  of  different  characteristics,  and 
some  soaps  are  more  suitable  for  scouring  than  others.  A  good  scouring 
Soap  should  be  readily  soluble  in  water  and  possess  high  emulsifying 
powers  towards  greasy  matters;  it  should  contain  no  fats  which  would 
act  deleteriously  on  the  fiber  or  leave  it  with  an  objectionable  odor  or  color. 
The  soap  should  furthermore  be  capable  of  easy  removal  from  the  wool 
after  scouring,  and  not  leave  behind  any  resinous  or  fatty  matters  of  an 
insoluble  character.  As  already  mentioned,  it  should  also  not  contain 
any  appreciable  quantity  of  free  caustic  alkali;  nor,  on  the  other  hand, 
should  it  contain  unsaponified  fat.  Soaps  made  from  olive  oil  are  usually 
considered  of  the  highest  grade  and  the  most  desirable  for  wool  scour- 
ing; although  soaps  made  from  cotton-seed  oil,  maize  oil,  tallow,  oleine 


88 


SCOURING  THE  TEXTILE  FIBERS 


o 
O 


a 

3 


tf 


> 


a 

SI 
o3 

O 


IMPURITIES  OF  RAW  COTTON 


89 


(the  liquid  fat  obtained  as  a  by-product  in  candle-making),  and  palm  oil 
are  also  extensively  employed.  Often  mixed  soaps  are  used,  such  as  olive 
or  cotton-seed  oil  soap  in  combination  with  a  tallow  soap.  Both  hard 
and  soft  soaps  are  used,  though  the  latter  are  generally  preferred  for  scour- 
ing raw  wool  as  well  as  yarn. 

10.  Boiling-out  of  Cotton. — Raw  cotton  is  unlike  wool  in  that  it 
contains  a  relatively  small  amount  of  natural  impurities  and  for  many 
purposes  cotton  is  not  scoured  at  all.  Whereas  raw  wool  cannot  be  manu- 
factured into  yarn  without  a  previous  removal  of  its  greasy  and  dirty  mat- 
ters, cotton  is  spun  without  any  such  preliminary  cleansing  being  required; 


Fig.  78. — Early  Type  Open  Kier  with  Injector. 


in  fact  the  impurities  that  are  present  in  raw  cotton  are  an  aid  rather  than  a 
hindrance  to  the  proper  spinning  of  this  fiber.  In  many  cases  of  dyeing, 
also,  a  previous  scouring  of  cotton  is  not  required.  The  impurities  in 
raw  cotton  consist  for  the  most  part  of  waxy  and  resinous  matters,  which 
are  classified  under  the  general  term  of  pectin  substances.  These  amount 
to  about  5  per  cent  on  the  weight  of  the  fiber.  By  reason  of  its  coating 
of  waxy  matters,  the  cotton  fiber  is  more  or  less  waterproof,  or  rather 
water-repellent,  and  will  not  readily  "wet-out"  when  placed  in  water. 
This  property  is  frequently  a  drawback  in  dyeing,  as  the  dye  solution  will 
not  penetrate  perfectly  and  evenly.  To  overcome  this  defect  it  is  neces- 
sary to  remove  the  waxy  coating  on  the  cotton,  and  this  is  best  done 
by  boiling  in  a  solution  of  caustic  soda,  soda  ash,  or  soap,  or  with  some  oil 


90 


SCOURING  THE  TEXTILE  FIBERS 


and  Safety  Valve 


Fig.  79. — Modem  Type  Open  Kier.     (Hiibner.) 


Fig.  80. — Open  Kier  for  Treating  Cloth  with  Caustic. 
(H.  W.  Butterworth  &  Sons  Co.) 


BOILING-OUT  OF  COTTON 


91 


which  has  the  property  of  dissolving  the  cotton-wax.  This  "wetting-out" 
of  cotton  for  the  purposes  of  dyeing  or  mordanting  is  simply  with  a  view 
of  allowing  it  to  become  quickly  and  thoroughly  saturated  with  the  solu- 
tions in  which  it  may  be  placed.  When  cotton  is  to  be  bleached,  however, 
it  is  not  only  necessary  to  scour  the  fiber  so  that  it  will  readily  wet-out, 


Fig.  81. — Closed  Kier  with  Plain  Injector  Circulation.     (Hubner.) 


but  also  to  completely  remove  all  resinous  substances,  otherwise  a  good 
clear  white  will  not  be  obtained  in  the  bleaching.  For  this  purpose,  it 
is  generally  necessary  to  boil  the  cotton  with  a  solution  of  caustic  soda 
(or  other  alkalies)  for  a  number  of  hours  and  usually  under  more  or  less 
pressure.     This  operation   is   termed  "boiling-out"  to  distinguish  from 


92 


SCOURING  THE  TEXTILE  FIBERS 


mere  "wetting-out."  In  the  scouring  of  cotton  it  is  probable  that  the 
waxy  and  resinous  substances  in  the  fiber  are  emulsified  or  dissolved. 
Caustic  soda  is  pro])ably  the  most  generally  employed  chemical  for  the 
scouring  of  cotton,  though  soda  ash  and  sodium  silicate  are  also  exten- 
sively used.  Often  mixtures  of  these  three  are  employed.  Soap  is  also 
an  efficient  medium  for  wetting-out  cotton,  though  it  appears  that  when 
a  very  thorough  boiling-out  process  is  required  a  more  strongly  alkaline 


Fig.  82. — Pressure  Kier  with  Rusden  Circulator.     (Textile-Finishing  Machinery  Co.) 


agent  is  desirable.  Formerly  lime  (slaked  in  water)  was  extensively 
employed  for  boiling-out  cotton  preliminary  to  bleaching  but  its  use 
is  rapidly  giving  way  to  that  of  caustic  soda.  Certain  so-called  "soluble 
oils"  (prepared  by  treating  castor  oil,  cotton-seed  oil,  etc.,  with  strong 
sulphuric  acid,  and  hence  also  called  "sulphated"  ods)  appear  to  possess 
the  property  of  quickly  dissolving  the  waxy  matters  from  cotton,  and 
these  are  sometimes  used  for  the  purpose  of  wetting-out  of  cotton  for  dye- 
ing.    They  are  also  at  times  used  in  the  process  of  boiling-out.     Fank- 


WETTING-OUT  OF  COTTON 


93 


hausine,  Sol  vine,  Monopol  Oil,  etc.,  are  compounds  of  this  character,  and 
consist,  for  the  most  part,  of  sulphonated  vegetable  oils.  For  the  purpose 
of  merely  wetting-out  it  is  probably  better  to  use  either  a  solution  of  soap 
or  a  soluble  oil,  rather  than  the  alkalies,  as  the  former  method  leaves  the 
cotton  somewhat  whiter  in  appearance  and  softer  in  feel.  It  is  probable 
that  when  boiled  with  solutions  of  caustic  soda  or  soda  ash  the  resinous 
matters  in  the  fiber  are  decomposed  with  the  formation  of  brown  coloring 


Fig.  83. — Pressure  Kier  with  Vacuum  Circul  tion.     (Jefferson  Patent.) 


matters,  and  as  a  result  the  cotton  has  a  darker  color  than  when  treated 
with  soap  or  oil. 

The  pectin  matters  in  cotton  may  also  be  removed,  or  rather  solu- 
bilized,  by  the  action  of  diastatic  ferments  or  extracts,  such  as  are  obtained 
from  malt  and  bran.  The  diastase  preparations  for  this  purpose  are  known 
under  various  names,  such  as  Diamalt,  Diastofor  Polyzime,  etc.  They  are 
used  in  the  form  of  a  weak  solution  (2  to  4  per  cent)  and  at  a  lukewarm 
temperature  (110  to  120°  F.)  The  cotton  goods  are  generally  steeped 
in  the  solution  overnight,  or  saturated  with  the  Hquor,  squeezed,  and 


94 


SCOURING  THE  TEXTILE  FIBERS 


laid  down  in  bins  in  the  moist  state  overnight.  The  diastase  acts  on  the 
pectin  matters  in  the  cotton,  converting  them  into  readily  soluble  materi- 
als, with  the  result  that  the  cotton  becomes  very  absorbent  and  is  easily 
wet-out.  This  method  of  removing  the  pectin  matters  from  cotton  is 
frequently  resorted  to  in  cases  where  it  is  not  desirable  to  employ  a 
kier  boil  with  an  alkali,  as  in  the  case  of  bleaching  cotton  cloth  with  colored 
stripes.  By  using  the  diastase  method  a  good  bleach  may  be  obtained 
without  injury  to  the  color. 


Fig.  84. — Pressure  Kier  with  Outside  Heater  and  Pump  Circulation, 
(W.  AUen  &  Sons  Co.). 


11.  The  Impurities  in  Raw  Silk. — Raw  silk  as  it  appears  in  trade 
does  not  much  resemble  the  brilliant  and  lustrous  fiber  seen  in  manu- 
factured silk  fabrics.  Raw  silk  consists  not  only  of  the  fiber  proper,  but 
also  of  a  large  amount  of  a  glue-like  substance  which  heavily  coats  the  fiber 
and  gives  it  a  harsh,  brittle  feel  and  hides  the  luster  and  whiteness  of  the 
true  fiber.  This  substance  is  known  as  silk-glue  or  sericin,  and  it  amounts 
to  about  25  per  cent  of  the  weight  of  the  raw  silk.  It  is  soluble  in  water, 
and  may  indeed  be  completely  removed  from  the  fiber  by  prolonged  boihng. 


IMPURITIES  IN  RAW  SILK 


95 


It  is,  however,  more  readily  removed  by  strong  solutions  of  soap,  and 
this  is  the  usual  method  employed.  The  fiber  proper  of  silk  is  known 
as  fibroin,  and  though  very  similar  in  chemical  composition  to  sericin, 
it  is  insoluble  in  water  or  soap  solutions.     The  most  of  the  coloring 


Fig.  85— Mather  Kier.    (Mather  &  Piatt). 


matter  in  raw  silk  is  also  contained  in  the  silk-glue  and  is  removed  along 
with  this  latter  substance.  Certain  raw  silks  (yellow-gum  Itahan  for 
instance)  are  of  a  deep  yellow  color,  but  when  completely  stripped  of  silk- 
glue  they  become  as  white  as  other  silks. 


96 


SCOURING  THE  TEXTILE  FIBERS 


12.  The  Boiling-ofE  of  Silk. — The  fiber  proper  of  raw  silk  is  covered 
with  a  glue-like  material  known  as  sericin.  The  presence  of  this  latter 
substance  makes  raw  silk  harsh  and  stiff  and  without  luster.  Boiling 
soap  solutions  remove  the  sericin  without  affecting  the  fiber  proper  of 
the  silk.  The  scouring  of  raw  silk,  or  the  removal  from  it  of  the  silk- 
glue,  is  usually  termed  "  boiling-off "  though  the  expressions  "degumming" 


Fig.  86.—"  Mather  "  Patent  Kier.     Longitudinal  Section.     (Mather  &.  Piatt). 

and  "stripping"  are  also  used.  When  completely  boiled-off  silk  will 
lose  in  weight  from  22  to  28  per  cent  and  is  known  in  the  trade  as  boiled- 
off  or  cuit  silk.  Frequently,  however,  all  of  the  silk-glue  is  not  removed, 
but  only  sufficient  to  make  the  silk  soft  and  lustrous  and  workable  in 
dyeing  or  bleaching.  Under  these  circumstances,  the  scouring  of  silk 
is  termed  soupling,  and  only  from  10  to  15  per  cent  in  weight  is  lost. 
Soupled  silk  is  also  known  in  trade  as  micuit.     It  is  usually  prepared 


BOILING-OFF  OF  SILK  97 

by  steeping  the  raw  silk  in  a  lukewarm  dilute  soap  bath  for  several  hours, 
then  rinsing  off  in  fresh  water.  After  soupling  the  silk  may  be  bleached, 
or  weighted  and  dyed.  After  bleaching  the  soupled  silk  is  frequently 
given  a  treatment  with  a  hot  (200°  F.)  solution  of  tartar  (using  3  to  4 
per  cent  of  the  cream  of  tartar  on  the  weight  of  the  silk) ;  this  causes  the 
silk-gum  remaining  on  the  fiber  to  soften  and  to  remain  in  that  condition 
permanently.  Soupled  silk  is  used  where  a  thick  full  fiber  is  required  as 
filling  yarn  (especially  for  moired  goods) ;  it  is  also  largely  used  for  warps. 
Furthermore,  raw  silk  is  sometimes  given  only  a  very  slight  scouring  for 
the  purpose  of  softening  the  fiber;  this  gives  what  is  called  ecru  silk, 
and  only  2  to  5  per  cent  in  weight  of  the  silk-glue  is  removed. 

Ecru  silk  is  frequently  prepared  by  simply  washing  the  raw  silk  in  luke- 
warm or  hot  water  without  the  use  of  any  soap  at  all.  As  only  a  small 
amount  of  the  gum  is  removed  this  fiber  is  hard  and  without  luster,  in 
fact  very  closely  resembles  raw  silk  in  appearance.  It  is  used  principally 
as  warp  threads  and  the  gum  is  therefore  left  on  purposely  to  act  as  a  size. 
The  scouring  of  silk  is  almost  invariably  accomplished  by  the  use  of  boiling 
solutions  of  soap.  The  length  of  time  and  the  number  of  soapings  given 
will  determine  how  much  of  the  sericin  will  be  removed.  For  a  complete 
boiling-off  a  strong  soap  solution  is  necessary  (from  4  ozs.  to  1  lb.  of  soap 
per  gallon),  and  the  time  required  is  from  1  to  2  hours,  and  this  treat- 
ment is  usually  repeated  with  a  second  soap  solution.  Unless  a  very 
soft  water  is  employed  it  is  also  necessary  to  add  a  small  amount  of  soda 
ash  to  the  scouring  bath  in  order  to  correct  the  hardness  of  the  water, 
otherwise  a  sticky  lime  soap  will  be  formed  which  will  adhere  to  the  fiber 
and  is  very  difficult  to  remove.  The  soap  employed  for  the  scouring  of 
silk  should  be  of  the  very  best  quality,  and  should  be  as  neutral  as  possible. 
The  presence  of  any  appreciable  free  alkali  in  the  scouring  bath  will  rapidly 
injure  the  silk  fiber,  causing  it  to  become  weakened,  discolored  and  luster- 
less.  Generally,  the  best  grade  of  hard  olive  oil  soap  is  used;*  soft  soaps 
are  not  employed  because  these  are  nearly  always  liable  to  contain  small 
quantities  of  free  alkali.  The  spent  scouring  baths  left  after  the  boiling- 
off  of  silk  (usually  repeated  lots  of  raw  silk  are  scoured  in  the  same  soap 
solution)  contain  a  large  quantity  of  silk-glue  together  with  the  soap  em- 
ployed. These  residual  baths  are  known  as  boiled-off  liquors  and  are 
extensively  used  as  an  adjunct  in  the  dyeing  of  silk,  being  added  in  con- 
siderable amount  to  the  dyebath  for  the  purpose  of  softening  the  dyed 
silk  and  promoting  the  even  distribution  of  the  color.  After  the  silk  has 
been  scoured  or  boiled-off  it  should  be  thoroughly  washed  with  water  in 
order  to  remove  all  trace  of  soapy  liquor,  otherwise  the  soap  will  dry  into 

*  One  of  the  chief  faults  in  the  use  of  a  cheap  soap,  or  of  a  soap  other  than  that  made 
from  oUve  oil,  is  the  objectionable  odor  which  such  soaps  are  liable  to  impart  to  the 
silk. 


98 


SCOURING  THE  TEXTILE  FIBERS 


o 
Pi 


OQ 


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Jih 


SCOURING  FOR  SOUPLED  SILK 


99 


the  fiber  and  cause  discolorations  and  imperfections.  After  the  scoured 
silk  is  dried,  in  order  to  soften  the  fiber  and  to  give  it  increased  luster, 
it  is  stretched  or  steamed.  This  is  merely  a  mechanical  treatment  which 
loosens  up  the  fine  and  delicate  filaments  of  the  silk  fiber  which  have 
become  more  or  less  matted  together  in  the  scouring  and  dyeing. 

Soupled  silk  is  produced  by  boiling  in  a  weaker  soap  solution  than 
when  boiled-off  silk  is  desired;  also  only  one  treatment  is  given  and  the 
time  of  boiling  is  reduced.  The  amount  of  silk-glue  removed  may  also 
be  regulated  by  scouring  at  temperatures  lower  than  the  boiling  point. 
For  yellow-gum  souple  silk  it  will  also  be  necessary  to  supplement  the 


Fig.  88. — Yarn  Washing  Machine 


scouring  with  a  bleaching  operation.  This  may  be  done  by  steeping  the 
scoared  and  rinsed  silk  in  a  cold  bath  of  aqua  regia  (consisting  of  1 
part  nitric  acid  and  2  parts  hydrochloric  acid)  at  4  to  5°  Tw.  until  the 
fiber  acquires  a  greenish  tinge.  It  is  then  thoroughly  washed  and  should 
lose  the  greenish  color  and  become  pure  white.  If,  instead  of  the  green 
tint  the  silk  acquires  a  yellow  tint  in  the  aqua  regia  bath,  it  indicates 
that  the  action  is  too  strong  or  has  proceeded  too  far.  Or  the  bleaching 
may  be  done  with  sulphurous  acid,  as  in  the  case  of  wool  (see  p.  108). 
In  both  cases  the  acid  must  be  completely  removed  from  the  silk  by  a 
thorough  rinsing.  For  the  production  of  ecru  silk  the  raw  fiber  is  merely 
softened  and  wet-out  by  working  in  a  lukewarm  dilute  soap  solution, 


100  SCOURING  THE  TEXTILE  FIBERS 

and  then  rinsing.  Spun  silk  (or  schappe  silk)  contains  but  a  small  pro- 
portion of  silk-gluo  as  most  of  this  has  been  removed  in  the  oper- 
ations previous  to  the  spinning  of  the  waste  silk.  Before  dyeing  spun 
silk,  however,  it  is  customary  to  wet  it  out  by  boiling  it  in  a  bath  contain- 
ing a  small  amount  of  soda  ash  and  soap.  Tussah  (or  wild  silk)  is  more 
difficult  to  boil-off  than  cultivated  silk,  as  it  contains  a  considerable 
amount  of  lime  compounds.  On  this  account  it  is  scoured  by  boiling 
in  a  solution  containing  ^  to  1  lb.  of  soda  ash  per  10  gallons  of  water. 
Then  after  rinsing  well  it  is  treated  in  a  lukewarm  bath  containing  3  to 
5  ozs.  of  hydrochloric  acid  per  10  gallons  of  water.  This  latter  treatment 
is  to  dissolve  the  Ume  compounds  and  thus  soften  the  fiber.  After  the 
acid  treatment,  of  course,  the  fiber  is  thoroughly  rinsed. 

13.  Relation  of  Water  to  Wool  Scouring. — The  use  of  the  proper 
kind  of  water  in  wool  scouring,  both  for  the  preparation  of  the  scouring 
bath  and  for  the  washing  of  the  wool  after  scouring,  is  a  matter  of  con- 
siderable importance.  The  use  of  hard  water,  as  such,  should  be  inter- 
dicted, on  account  of  its  bad  action  with  soap  solutions.  By  a  "hard" 
water  is  meant  one  containing  considerable  amounts  of  dissolved  mineral 
substances,  usually  compounds  of  calcium  (lime),  magnesium,  and  some- 
times iron.  These  mineral  substances  in  solution  combine  with  soap  to 
form  insoluble  and  sticky  precipitates,  which  cause  not  only  a  loss  of  soap 
and  a  ccJnsequent  decrease  in  the  scouring  power  of  the  bath,  but  also 
these  precipitates  adhere  to  the  fiber  and  are  difficult  of  removal.  Water 
having  a  hardness  of  100  parts  per  million  (10°)  will  render  useless  about 
one-third  ounce  of  soap  per  gallon.  As  this  represents  water  of  only  a 
fair  degree  of  hardness,  it  may  be  seen  that  the  loss  in  soap  through  hard 
water  may  become  a  very  considerable  item  of  expense.  One  pound  of 
calcium  carbonate,  or  its  equivalent  in  calcium  sulphate  or  magnesimn 
salts,  in  solution  in  water  destroys  about  10  lbs.  of  good  average  soap. 
A  thousand  gallons  of  water  for  each  degree  of  hardness  (parts  of  CaCOs 
per  100,000)  destroy  about  1  lb.  4  ozs.  of  soap.  Sometimes  the  "hard- 
ness" of  water  is  removable  by  simply  boiling;  it  is  then  termed  temporary 
hardness,  and  is  principally  due  to  the  presence  of  carbonic  acid  gas  hold- 
ing calcium  carbonate  (limestone)  in  solution.  On  boiling,  the  carbonic 
acid  gas  is  driven  off  and  in  consequence  the  calcium  carbonate  is  pre- 
cipitated. Perinanent  hardness,  on  the  other  hand,  is  not  removable  by 
boihng,  and  is  chiefly  due  to  the  presence  of  calcium  sulphate  (gypsum). 
To  remove  hardness  of  this  character  soda  ash  is  usually  added  sufficient 
to  precipitate  the  calcium  compound  as  the  highly  insoluble  carbonate. 
Or,  small  quantities  of  oxalic  acid  and  ammonia  may  be  added,  which 
causes  the  precipitation  of  the  lime  as  calcium  oxalate.  Before  hard 
water  is  used  in  connection  with  wool  scouring  it  should  be  "corrected" 
in  one  of  the  ways  here  indicated.     Water  containing  any  appreciable 


TREATMENT  OF  HARD  WATER 


101 


amount  of  iron  is  especially  objectionable  for  use  in  scouring,  as  the  iron 
readily  becomes  firmly  fixed  in  the  fiber,  leading  to  many  bad  defects. 
Iron  may  be  best  removed  from  water  by  proper  aeration  and  filtration. 
Should  the  water  contain  sediment  in  any  appreciable  amount  it  should 
be  properly  filtered  before  use.  River  or  pond  water  is  liable  to  con- 
tain a  larger  amount  of  sediment  than  spring  or  well  water,  but,  on  the 
other  hand,  as  a  rule,  its  hardness  is  not  so  great,  nor  is  it  as  hable  to  con- 
tain iron. 


Fig.  89. — Horizontal  Pressure  Filter.     (Hungerford  System). 


Water  containing  organic  matter  in  solution  will  often  car?y  with  it 
considerable  iron  also  held  in  solution.*  These  impurities,  together  with 
finely  suspended  matters  and  color  bearing  substances,  may  best  be 
removed  by  treating  the  water  with  a  small  amount  of  alum  and  filter- 
ing. The  action  of  the  alum  is  to  cause  a  coafi,ulation  of  the  organic 
matters,  which  in  their  precipitation  carry  down  with  them  all  other 
impurities  including  the  iron  and  coloring  matters,  thus  yielding  a  clear 
filtered  water  which  is  pure  and  free  from  iron.  Care  must  be  taken  to 
see  that  an  excess  of  alum  is  not  added,  otherwise  it  would  introduce  an 
objectionable  feature  into  the  water.     If  the  water  is  also  hard  and  it  is 

*  Iron  is  a  very  objectionable  impurity  in  water,  especially  for  bleaching  as  even 
small  traces  of  this  metal  tend  to  give  a  yellowish  appearance  to  the  bleach. 


102 


SCOURING  THE  TEXTILE  FIBERS 


desired  to  soften  as  well  as  clarify  it,  soda  ash  may  be  fed  into  the  water 
in  addition  to  the  alum  and  before  filtering.  A  good  test  to  show  if  there 
is  an  excess  of  alum  in  the  filtered  water,  is  to  place  a  sample,  about  50  cc. 
of  the  water,  in  a  porcelain  dish,  add  a  few  drops  of  acetic  acid  and  then  a 
few  drops  of  a  solution  of  hematoxylin;  if  a  pinkish  or  violet  color  per- 
sists after  stirring,  it  indicates  the  presence  of  alum,  but  if  the  color  is 
simply  brown  and  free  from  a  violet  tinge,  the  water  is  free  from  alum. 

In  filtering  water  for  dyehouses  and  bleacheries  it  is  probably  more 
efl&cient  to  use  closed  mechanical  pressure  filters  rather  than  the  open 


Fig.  90. — Gravity  Filter.     (Hungerford) 


type  of  gravity  filter.  Both  use  sand  as  the  filtering  medium,  but  the 
pressure  filter  is  more  easily  regulated  and  adjusted  to  the  needs  at  hand; 
also  it  occupies  much  less  space,  and  if  of  the  proper  type  is  very  readily 
cleaned  by  simply  reversing  the  flow  of  water  for  a  short  time. 

Another  form  of  water  treatment  for  the  purpose  of  obtaining  a  very 
soft  water  is  known  as  the  "Permutit"  process.  This  process  is  only 
for  the  softening  of  the  water  and  presupposes  a  filtering  at  first  through 
a  suitable  sard  filter  for  the  purpose  of  removing  suspended  and  organic 
matters.     In  the  Permutit  process  a  form  of  pressure  filter  is  used  employ- 


PURIFICATION  OF  WATER 


103 


ing  an  artifical  zeolite  as  the  filtering  mechanism.  This  mineral  has  the 
peculiar  property  of  exchanging  its  sodium  content  for  calcium  or  magne- 
sium when  brought  into  contact  with  water  containing  compounds  of 
these  latter  metals.  Thus  a  hard  water  containing  calcium  sulphate 
when  filtered  through  a  layer  of  this  zeolite  gives  up  its  calcium  to  the 


Fig.  91. — Water  Softener.     (Booth  System). 


zeolite  and  receives  in  exchange  a  corresponding  quantity  of  sodium,  so 
that  in  place  of  calcium  sulphate  the  water  will  come  from  the  filter  con- 
taining an  equivalent  amount  of  sodium  sulphate.  By  this  process 
water  of  zero  hardness  may  readily  be  obtained.  The  zeolite  filtering 
medium  is  regenerated  by  passing  through  it  a  solution  of  common  salt, 
which  takes  out  the  lime  and  replaces  it  with  sodium  again. 


104 


SCOURING  THE  TEXTILE  FIBERS 


Pure  water  is  just  as  necessary  for  bleaching,  dyeing,  and  washing 
as  it  is  for  scouring.  Many  of  the  defects  in  these  processes  can  be  traced 
back  to  the  use  of  impure  or  hard  water,  as  the  metalHc  salts  present  in 
such  water  may  cause  stains,  streaks,  and  discolorations.  The  special 
features  in  these  cases  will  be  discussed  in  their  appropriate  place  when 
these  subjects  come  up  for  consideration,  as  the  matter  may  then 
be  dealt  with  more  intelligently  when  a  fuller  knowledge  of  the  conditions 
is  acquired. 


Fig.  92.— Water  Softener.     (Permutit  System). 


In  some  dj-ehouscs  the  water  obtained  from  condensed  steam  is  often 
employed  where  a  very  pure  water  is  desired.  In  such  cases  care  should 
be  had  that  the  water  is  free  from  oil  or  grease  which  may  frequently  be 
present  if  the  exhaust  steam  from  an  engine  is  used.  This  condensed 
water  is  practically  pure  distilled  water  and  in  this  condition  very  readily 
dissolves  iron  from  iron  pipes  or  tanks  in  which  it  may  be  stored ;  there- 
fore either  wooden  pipes  should  be  used,  or  if  of  iron  they  should  be  coated 
inside  with  pitch.  The  same  is  also  true  of  storage  tanks,  which  should 
be  of  wood  wherever  possible.     If  these  precautions  are  not  used,  the 


EXPERIMENTAL  STUDIES  105 

use  of  condense  water  may  result  in  serious  defects  by  reason  of  the  large 
amount  of  iron  with  which  it  may  become  contaminated. 

The  proper  chemical  treatment  necessary  for  any  given  water  in  order 
to  obtain  a  pure  soft  water  can  be  determined  only  by  a  careful  chemical 
analysis  of  the  water  by  those  experienced  in  the  problems  dealing  with 
water  purification. 

14.  Experimental.     Exp.  17.     Scouring  Raw   Wool  by  the    Emulsion    Process. — 

Weigh  out  10  grams  of  raw  wool  and  scour  it  in  a  bath  containing  300  cc.  of  water, 
5  grams  of  soda  ash,  and  2  grams  of  soap.  Have  the  soap  thoroughly  dissolved  before 
adding  it  to  the  bath.  Work  the  wool  gently  at  140°  F.  for  one-half  hour,  or  until  it 
seems  thoroughly  cleansed.  Wash  well  in  fresh  warm  water  to  remove  all  soapy  liquor. 
Dry  and  rcweigh.  Calculate  the  percentage  of  loss  or  "  shrinkage."  In  working  the 
wool  in  the  scouring  bath  care  should  be  taken  not  to  agitate  the  fibers  too  vigorously 
or  the  wool  will  become  matted  or  felted  together. 

Exp.  18.  Use  of  Potash  in  Scouring  Wool. — Prepare  a  scouring  bath  containing 
300  cc.  of  water,  5  grams  of  pearl  ash  (potassium  carbonate  or  potash),  and  2  grams  of 
soap.  Scour  a  10-gram  sample  of  the  same  wool  as  used  above  and  proceed  in  the 
same  manner.  Wash  well  in  warm  water,  allow  to  dry  and  reweigh.  Compare  the 
two  samples  thus  scoured  by  the  use  of  the  two  alkalies. 

Exp.  19.  Effect  of  High  Temperatures  in  Scouring. — Use  the  same  bath  as  employed 
in  Exp.  17  and  scour  another  10-gram  sample  of  the  same  kind  of  raw  wool,  but  bring  the 
bath  to  the  boil  for  one-half  hour.  Rinse  as  before  in  warm  water,  and  allow  to  dry. 
Reweigh  and  calculate  the  percentage  of  loss,  and  also  compare  the  general  appearance 
and  "  feel  "  of  the  wool  with  that  scoured  in  the  first  experiment. 

Exp.  20,  Effect  of  Using  Excessive  Alkali  in  Scouring  Raw  Wool. — Scour  a  10-gram 
sample  of  raw  wool  in  a  bath  containing  300  cc.  of  water  and  20  grams  of  soda  ash. 
Work  for  one-half  hour  at  a  temperature  of  140°  F.;  then  wash  well  in  warm  water  and 
allow  to  dry.  Calculate  the  percentage  of  loss,  and  compare  the  general  appearance 
and  feel  with  the  samples  scoured  by  the  use  of  less  alkali. 

Exp.  21.  Scouring  Woolen  Yarn  by  the  Usual  Method. — Prepare  a  bath  containing 
300  cc,  of  water,  10  grams  of  soap,  and  2  grams  of  soda  ash.  Scour  a  weighed  test  skein 
of  woolen  yarn  in  this  bath  for  one-half  hour  at  a  temperature  of  140°  F.,  then  wash  in 
fresh  water  and  allow  to  dry.  Reweigh  after  drying  and  calculate  the  percentage  of 
loss  due  to  scouring. 

Exp,  22.  Scouring  Woolen  Yam  Containing  Iron. — Yarn  of  this  nature  is  best 
scoured  in  baths  containing  only  soap,  as  soda  ash  or  potash  will  form  an  insoluble 
compound  with  the  iron  in  the  fiber  which  cannot  be  removed,  and  which  will  cause  the 
yarn  to  dye  up  dull.  Scour  a  test  skein  of  woolen  yarn  containing  iron  in  the  same 
bath  as  employed  for  the  previous  experiment  and  in  the  same  manner;  wash  well  and 
dry.  Scour  a  second  skein  of  similar  yarn  in  a  bath  containing  300  cc.  of  water  and  10 
grams  of  soap  for  one-half  hour  at  140°  F.;  wash  well  and  dry.  Compare  the  appear- 
ance of  the  two  scoured  skeins. 

Exp.  23.  Scouring  Cotton  with  Caustic  Soda. — Prepare  a  bath  containing  5  grams  of 
caustic  soda  to  300  cc.  of  water,  and  boil  a  skein  of  cotton  yarn  therein  for  one-half  hour; 
then  wash  in  fresh  water  until  all  trace  of  the  caustic  soda  has  been  removed  from  the 
cotton  and  dry.  Weigh  the  skein  before  and  after  the  scouring  and  calculate  the  per- 
centage of  loss. 

Exp,  24,  Scouring  Cotton  with  Soda  Ash. — Prepare  a  bath  containing  5  grams  of 
soda  ash  and  300  cc.  of  water,  and  boil  a  skein  of  cotton  yarn  therein  for  one  hour. 
Wash  well  in  fresh  water  and  dry.     Weigh  the  skein  before  and  after  scouring  and  cal- 


106  SCOURING  THE  TEXTILE  FIBERS 

culate  the  percentage  of  loss.  Compare  this  skein  with  that  in  the  preceding  test  as  to 
amount  of  loss,  color,  softness,  etc. 

Exp.  25.  Scouring  Cotton  with  Soap. — Prepare  a  bath  containing  5  grams  of  soap 
and  300  cc.  of  water,  and  boil  a  weighed  skein  of  cotton  yarn  therein  for  one-half  hour. 
Wash  in  fresh  water  and  dry.  Reweigh  and  calculate  the  percentage  of  loss  Compare 
this  skein  with  the  others  of  the  above  experiments. 

Exp.  26.  Scouring  Cotton  with  Soluble  Oil. — Prepare  a  bath  containing  2  cc.  of 
Monopol  Oil  (50  per  cent  solution)  and  300  cc.  of  water.  Work  a  skein  of  cotton 
yarn  in  this  bath  for  one-half  hour  at  180°  F.;  then  wash  and  dry.  Weigh  the  skein 
before  and  after  scouring  and  calculate  the  percentage  of  loss.  Compare  the  skein  with 
others  in  the  previous  experiments  as  to  color,  softness  of  feel,  etc. 

Exp.  27.  Scouring  of  Raw  Silk. — Take  a  weighed  skein  of  raw  silk  yarn  and  boil 
it  for  one  hour  in  a  solution  containing  250  cc.  of  water  and  25  grams  of  olive  oil  hard 
soap;  then  wash  well  in  fresh  warm  water  and  dry.  Reweigh  and  calculate  the  per- 
centage of  loss.  As  a  rule,  to  completely  degum  the  silk  it  is  necessary  to  boil  in 
several  soap  baths.  Notice  the  difference  in  the  appearance  and  "  handle  "  of  the 
boiled-off  silk.  Stretch  and  squeeze  the  dried  boiled-off  skein  so  as  to  soften  up  the 
fiber  and  luster  it.  It  will  be  found  that  most  of  the  coloring  matter  of  the  raw  silk  is 
in  the  sericin  and  is  removed  in  the  boiling-off. 


CHAPTER  III 
BLEACHING  OF  WOOL  AND  SILK 

1.  Bleaching  WooL — The  wool  fiber  in  its  natural  condition  always 
contains  some  pigment  matter;  even  the  usual  so-called  "white"  wool 
contains  a  small  amount  of  a  j-ellowish  brown  color  which  it  is  necessary 
to  remove  in  order  to  have  a  fiber  possessing  a  clear  white  color.  In  some 
grades  of  wool  the  amount  of  pigment  matter  may  be  comparatively 
large,  giving  the  brown  or  black  wools.  These  wools,  however,  are  small 
in  amount  compared  with  the  white  wools  and  are  seldom,  if  ever, 
bleached.  The  method  of  bleaching  wool  by  the  tinting  process  depends 
on  the  neutraHzation  of  the  slight  yellow  tint  of  the  natural  wool  by  dye- 
ing the  fiber  wdth  a  delicate  tmt  of  blue  or  violet  coloring  matter.  It  is 
not  really  a  removal  or  destruction  of  the  natural  pigment,  but  simply 
a  change  of  the  j'ellow  tint  to  one  of  a  grayish  tone.  The  latter  being 
less  susceptible  to  the  eye  causes  the  wool  to  appear  white.  The  color 
relations  in  the  case  are  based  on  the  fact  that  yellow  and  violet  are  com- 
plementar}'  colors,  so  that  when  mixed  in  small  amount  they  produce 
gray.  For  the  tinting  color  it  is  best  to  use  a  blue  dyestuff  with  a  slight 
violet  tone,  such  as  a  very  blue  tone  of  Acid  Violet.  Oxalic  acid  is  used 
with  the  dyestuff  to  render  the  solution  slightly  acid  and  thus  develop 
the  color.  The  actual  amount  of  color  required  is  very  small  and  care 
must  be  exercised  not  to  overtint  the  wool,  or  a  bluish  tone  will  be  obtained. 
Wool  bleached  in  this  manner,  of  com'se,  will  not  possess  as  clear  a  white 
color  as  that  in  which  the  natural  pigment  is  actually  destroyed;  it  will 
only  give  a  dull,  cloudy-looking  white. 

Sulphurous  acid,  or  one  of  its  compounds,  is  the  agent  mostly  employed 
for  the  true  bleaching  of  wool.  Sulphurous  acid  is  a  strong  reducing 
agent;  that  is  to  say,  it  has  a  strong  "affinity"  for  oxygen.  When  act- 
ing on  many  organic  coloring  matters  (such  as  the  natural  pigment  in 
wool)  it  "reduces"  them,  thus  causing  them  to  be  converted  into  color- 
less substances.  Many  coloring  matters,  however,  after  being  thus 
reduced,  are  capable  of  becoming  oxidized  on  exposure  to  air  so  as  to 
yield  again  the  original  color;  this  appears  to  be  the  case  with  the  color- 
ing matter  in  wool,  for  when  bleached  with  sulphurous  acid  the  yellow 
tint  becomes  gradually  restored  on  exposure  to  the  air. 

107 


108  BLEACHING  OF  WOOL  AND  SILK 

Bleaching  by  the  use  of  sulphurous  acid  gas  is  the  method  mostly 
practiced  for  the  bleaching  of  wool.  The  process  is  rather  simple;  the 
wool  (either  in  loose  state,  yarn,  or  cloth)  is  moistened  and  spread  out  or 
hung  in  a  room  where  it  is  subjected  to  the  action  of  the  sulphurous  acid 
gas  for  ten  to  twenty  hours.  The  gas  is  produced  generally  by  the  burn- 
ing of  sulpliur  in  an  iron  or  earthenware  pot,  sometimes  in  the  bleaching 
room  itself,  though  it  is  considered  better  to  burn  the  sulphur  in  an  appa- 
ratus outside  of  the  bleaching  room  and  to  lead  the  gas  into  the  latter. 
From  the  use  of  the  so-called  "stove"  for  burning  the  sulphur,  this  proc- 
ess of  bleaching  has  received  the  name  of  "sto\'ing."  The  wool  (in 
whatever  form)  must  be  thorough^  scoured  for  bleaching  and  should 
be  in  a  moist  (though  not  wet)  condition,  as  the  gas  acts  but  slowly  on 
the  dn,'  wool.  The  material  should  also  be  so  distributed  in  the  bleach- 
ing room  that  the  gas  may  easily  come  in  contact  with  all  parts  of  the 
fiber.  Usuallj'  the  gas  is  allowed  to  pass  from  one  end  of  the  room  to 
the  other  and  thence  out  through  a  flue.  The  bleaching  chamber  must 
be  so  constructed  that  the  condensed  vapors  (which  consist  of  rather  con- 
centrated sulphuric  acid)  cannot  drop  on  the  wool,  else  spotting  will 
result,  or  the  fiber  may  even  be  seriously  injured.  Also  the  room  should 
not  contain  exposed  iron  parts  which  may  come  in  contact  with  the  sul- 
phur gas,  as  the  metal  will  rapidly  be  attacked  and  the  condensed  drops 
that  may  fall  on  the  wool  will  cause  bad  spotting. 

2.  Use  of  Sodium  Bisulphite. — The  use  of  this  chemical  for  the 
bleaching  of  wool  is  merely  a  convenient  method  for  the  application  of 
sulphurous  acid  in  the  form  of  a  solution.  The  bleaching  agent,  in  fact, 
is  exactl}'  the  same  as  when  sulphurous  acid  gas  is  emplo\'ed,  and  the 
character  of  the  bleach  obtained  in  the  two  cases  is  practically  identical. 
Sodium  bisulphite  has  the  chemical  formula  XaHSOs,  and  when  dis- 
solved in  water  its  solution  practically  consists  of  sodium  sulphite  and  sul- 
phurous acid : 

2  XaHSOs  =  Na2S03+H2S03. 

When  wool  is  steeped  in  this  solution  the  sulphurous  acid  acts  directly 
upon  the  fiber  as  a  bleaching  agent,  and  moreover,  the  wool  also  becomes 
saturated  with  the  sodium  sulphite.  Hence  the  wool  is  subsequently 
treated  with  a  solution  of  sulphuric  acid,  which  reacts  with  the  sodium 
sulphite,  forming  sodium  sulphate  and  liberating  another  portion  of  sul- 
phurous acid : 

XaoSOs  -f  H2SO4  =  XazSO^+HaSOa. 

This  second  portion  of  sulphurous  acid  also  aids  materially  in  the  bleach- 
ing of  the  wool. 

Bleached  wool  is  usually  tinted  with  a  blue  or  bluish  violet  coloring 
matter  in  order  to  give  to  the  fiber  a  bluish  white  tone  which  is  more  pleas- 


BLEACHING  WITH  SODIUM  BISULPHITE  109 

ing  to  the  eye  than  the  flat  bleach.  A  minute  quantity  of  a  blue  shade 
of  Acid  Violet  is  useful  for  this  purpose,  and  it  is  generally  applied  in  the 
rinsing  bath  after  the  bleaching,  adding  a  small  quantity  of  oxalic  acid 
to  the  water  for  the  purpose  of  developing  the  color  and  also  for  the  pur- 
pose of  removing  any  trace  of  brownish  stain  due  to  the  presence  of 
iron  compounds. 

The  bleaching  bath  when  using  sodiimi  bisulphite  is  prepared  as  fol- 
lows: 

500  gallons  cold  water, 
12  gallons  sodium  bisulphite  solution  of  32°  Tw., 
2|  pints  oil  of  vitriol. 
This  bath  will  be  of  sufficient  size  to  bleach  100  lbs.  of  scoured  wool. 
The  tanks  employed  should  be  of  wood,  and  may  be  either  round  or  rect- 
angular in  form.  The  wool  is  worked  in  the  liquor  until  thoroughly  satu- 
rated, and  then  allowed  to  steep  overnight  underneath  the  solution.  It 
is  then  taken  out  and  drained  and  tinted  in  a  second  bath  containing  500 
gallons  of  water  and  about  ^  oz.  of  Alkali  Violet  6B  at  a  temper- 
ature of  100°  F.  for  fifteen  minutes.  The  wool  is  finally  rinsed  and  dried. 
The  water  employed  for  both  the  bleaching  and  tinting  baths  should 
be  as  pure  as  possible,  and  more  especially  free  from  iron.  A  variety  of 
dyestuffs  besides  the  one  mentioned  may  be  used  for  tinting,  such  as 
Alkah  Violet  4BN,  Acid  Violet  6BN,  etc.  In  order  to  prevent  streaks 
in  the  tint  the  dyestuff  employed  should  first  be  dissolved  in  2  gallons 
of  hot  pure  water  and  before  being  added  to  the  bath  the  solution  should 
be  filtered  through  a  cotton  cloth.  To  obtain  a  tint  which  shall  be  very 
fast  to  fulling  a  little  Indigo  reduced  with  hydrosulphite  may  be  used  as 
the  coloring  matter. 

Mention  has  already  been  made  of  the  fact  that  the  bleach  obtained 
on  wool  by  means  of  sulphurous  acid  is  not  a  permanent  one,  but  the  yel- 
low tint  reappears  after  prolonged  exposure  to  the  air.  Furthermore,  it 
appears  to  be  practically  impossible  to  remove  every  trace  of  sulphurous 
acid  from  the  fiber,  however  thorough  the  washing  may  be  after  the 
bleaching.  The  wool  apparently  combines  in  a  chemical  manner  with 
the  sulphurous  acid,  and  this  leads  to  two  defects  in  the  bleached  wool; 
in  the  first  place,  the  presence  of  the  sulphurous  acid  apparently  holds 
the  pigment  in  the  fiber  in  a  reduced  state  so  that  the  bleach  lacks  per- 
manency of  character,  as  already  noted;  secondly,  the  presence  of  the 
sulphurous  acid  is  liable  to  act  injuriously  on  other  dyed  colors  with 
which  the  bleached  wool  may  subsequently  come  in  contact  when  woven 
into  cloth.  This  effect  is  illustrated  experimentally  by  the  action  of 
the  bleached  wool  in  contact  with  wool  dyed  with  Magenta.  For  these 
reasons  it  has  long  been  recognized  as  desirable  to  remove  from  the  bleached 
wool  all  trace  of  sulphurous  acid.    This  may  readily  be  accomplished  by 


110  BLEACHING  OF  WOOL  AND  SILK 

treating  the  bleached  material  with  a  solution  containing  a  suitable  oxidiz- 
ing agent.  Potassium  permanganate  has  been  quite  extensively  employed 
for  this  purpose.  By  its  action  the  sulphurous  acid  is  converted  into 
sulphuric  acid,  which  is  harmless  as  far  as  the  effects  outlined  above  are 
concerned.  In  the  use  of  this  agent,  however,  great  care  must  be  exer- 
cised not  to  employ  an  excess  beyond  that  needed  to  react  with  the  sul- 
phurous acid,  otherwise  a  brown  deposit  of  an  oxide  (or  hydrate)  of  man- 
ganese will  be  left  on  the  wool,  and  a  subsequent  treatment  with  a  solution 
of  sodium  bisulphite  will  have  to  be  given  to  remove  this  deposit.  In- 
stead of  using  potassium  permanganate  in  this  connection  it  would  prob- 
ably be  better  to  employ  a  small  quantity  of  sodium  peroxide,  which 
would  have  the  same  effect  on  the  trace  of  sulphurous  acid  without  the 
attendant  defect  of  discoloration  through  the  addition  of  an  excess  of  the 
reagent.  The  presence  of  traces  of  sulphurous  acid  in  wool  may  be  con- 
veniently detected  by  wetting  the  wool  in  a  small  quantity  of  water  and 
adding  a  few  drops  of  a  mixture  of  iodic  acid  and  starch  solutions;  if  sul- 
phurous acid  is  present  a  violet  or  blue  color  will  be  formed. 

3.  Bleaching  Wool  with  Peroxides. — The  use  of  sodium  peroxide 
as  a  bleaching  agent  for  wool  is  fast  becoming  of  considerable  practical 
importance.  Hydrogen  peroxide  (in  solution)  is  also  employed  for  this 
purpose,  but  its  cost  is  generally  considered  to  be  somewhat  higher.  The 
bleaching  action  of  these  two  substances,  however,  is  identical,  and  is 
due  to  the  nascent  oxygen  which  they  are  capable  of  liberating.  Hydro- 
gen peroxide  has  the  chemical  formula  H2O2,  and  is  prepared  by  the  action 
of  sulphuric  acid  on  barium  peroxide.  As  employed  in  the  arts  it  con- 
sists of  a  comparatively  dilute  solution  (about  3  per  cent)  of  hydrogen 
peroxide  in  water*  though  solutions  containing  as  high  as  10  per  cent  are 
now  available.  The  chemical  formula  of  sodium  peroxide  is  Na202;  it 
is  prepared  by  heating  metallic  sodium  in  air  or  oxygen.  It  occurs  as 
a  yellowish  white  powder  and  may  be  obtained  of  a  high  degree  of 
purity.  Some  care  must  be  taken  in  the  handling  and  using  of  sodium 
peroxide,  as  it  is  easily  decomposed  in  the  presence  of  moisture  and  organic 
matter  with  the  evolution  of  large  volumes  of  oxygen  which  may  lead  to 
explosions  or  fires.  When  handled  with  intelligent  precaution,  however, 
it  is  by  no  means  a  dangerous  chemical.  It  should  be  stored  in  a  cool, 
dry  place  in  comparatively  small  tins  (the  usual  commercial  size  is  that 
containing  10  lbs.),  and  should  be  kept  from  contact  with  water  or  from 
organic  matter  such  as  paper,  excelsior,  etc.  As  the  reaction  which  occurs 
between  sodium  peroxide  and  water  is  a  very  violent  one,  its  solution 

*  In  order  to  prevent  the  decomposition  of  the  peroxide  and  the  consequent  loss  in 
strength,  it  is  customary  to  add  a  small  quantity  of  acetanilide  to  the  solution  as  a  pre- 
servative. Sometimes  phosphoric  acid  is  also  added  for  the  same  purpose,  but  it  is  not 
as  efficient.     The  addition  of  uric  acid  or  barbituric  acid  is  also  very  effective. 


BLEACHING  WITH  SODIUM  PEROXIDE  111 

should  be  carefully  undertaken.  Large  quantities  or  lumps  of  sodium  per- 
oxide should  never  be  added  to  water,  as  an  explosion  or  fire  is  liable  to 
result.  The  peroxide  should  be  sifted  gradually  into  the  water  with  con- 
stant stirring.  When  sodium  peroxide  is  dissolved  in  water  caustic  soda 
and  hydrogen  peroxide  are  formed: 

Na202+2H20  =  2NaOH+H202. 

Its  bleaching  effect  is  due  to  the  ready  decomposition  of  the  hydrogen 
peroxide  in  contact  with  organic  matter  (such  as  wool): 

H202  =  H20  +  0. 

The  oxygen,  at  the  moment  of  its  liberation  in  such  a  manner,  is  especially 
reactive  (so-called  nascent  oxygen),  and  easily  destroys  the  organic  color- 
ing mattei's  of  which  the  pigment  of  the  wool  consists.  It  is  necessary 
to  neutralize  the  caustic  soda  in  the  solution  by  the  addition  of  sulphuric 
acid,  as  the  presence  of  the  caustic  alkali  in  the  bleaching  bath  would 
rapidly  destroy  the  wool  fiber.  On  this  accoimt  the  bath  is  usually  pre- 
pared by  first  adding  the  requisite  amount  of  sulphuric  acid  to  the  water, 
and  then  slowly  adding  the  sodium  peroxide.  Under  these  circumstances 
the  peroxide  reacts  with  the  sulphuric  acid  to  form  sodium  sulphate 
(glaubersalt)  and  hydrogen  peroxide : 

Na202  +  H2SO4  =  Na2S04 + H2O2. 

In  order  to  insure  the  fact  that  there  is  no  free  caustic  soda  in  the  solution 
it  is  best  to  use  a  slight  excess  of  acid,  which  may  be  indicated  by  testing 
the  bath  with  a  piece  of  blue  litmus  paper.  This  will  be  turned  red  in  the 
presence  of  an  excess  of  acid.  The  bleaching  effect  of  the  dissolved  hydro- 
gen peroxide,  however,  is  stronger  in  an  alkaline  solution  than  in  an  acid 
one;  this  is  due  to  the  fact  that  the  peroxide  more  readily  decomposes 
in  the  former  solution.  Therefore  where  the  bleaching  bath  is  in  actual 
use  it  should  be  made  slightly  alkaline  with  a  reagent  which  will  not  be 
injurious  to  the  wool.  Sodium  silicate  has  been  found  to  be  most  suitable 
for  this  purpose,  though  ammonia  or  borax  may  also  be  used.  In  this 
connection  it  must  be  remarked  that  a  large  excess  of  sulphuric  acid  must 
be  avoided,  otherwise  when  the  silicate  is  added  it  may  separate  in  a  jelly- 
like mass  and  ruin  the  bath.  During  the  bleaching  of  the  wool  the  bath 
should  be  maintained  at  a  temperature  of  about  100°  F.  If  the  temper- 
ature is  much  higher  than  this  the  hydrogen  peroxide  will  be  too  rapidly 
decomposed  and  loss  of  oxygen  will  be  occasioned;  if  the  bath  is  too 
strongly  alkaline  a  similar  condition  will  result. 

The  sodium  peroxide  bleaching  bath  must  be  contained  in  a  wooden 
vat  and  the  pipes  used  for  connections  and  heating  should  be  of  lead. 
The  presence  of  all  other  metals,  especially  iron,  should  be  rigidly  excluded; 


112  BLEACHING  OF  WOOL  AND  SILK 

even  the  sulphuric  acid  and  the  water  employed  in  the  bath  should  be 
perfectly  free  from  iron,  otherwise  very  inferior  results  will  be  obtained. 
A  suitable  strcnfj;th  for  the  bleaching  bath  is  5  lbs.  5  ozs.  of  sulphuric  acid 
(168°  T\v.)  and  4  lbs.  of  sodium  peroxide  (98  per  cent)  per  100  gallons 
of  water.  The  character  of  the  wool  or  the  nature  of  the  material  to  be 
bleached  may  necessitate  a  somewhat  stronger  bath  than  this,  in  which 
case  the  same  relative  proportions  of  acid  and  peroxide  should  be  used. 

Wool  bleached  with  sodium  peroxide  does  not  exhibit  the  same  defects 
as  noted  under  the  bleaching  with  sulphurous  acid.  It  does  not  retain 
any  substance  deleterious  to  dyed  colors,  nor  does  the  yellow  tint  of  the 
natural  pigment  return  on  exposure  to  the  air,  for  this  pigment  appears 
to  be  permanently  destroyed  by  the  peroxide.  Attention  may  here  be 
drawn  to  the  radical  difference  in  the  principle  of  bleaching  with  sul- 
phurous acid  and  with  sodium  peroxide.  In  the  former  case  the  bleach- 
ing takes  place  through  the  reducing  action  of  the  sulphur  dioxide,  whereas 
in  the  latter  case  the  bleaching  is  brought  about  by  the  strong  oxidizing 
action  of  the  peroxide. 

In  order  to  ascertain  if  the  bleaching  bath  of  sodium  peroxide  after 
use  still  contains  active  oxygen  for  further  use  in  bleaching,  the  following 
test  may  be  carried  out:  A  small  quantity  of  the  residual  liquor  is  placed 
in  a  test  tube  and  a  few  drops  of  a  dilute  solution  of  potassium  perman- 
ganate are  added.  If  the  bath  still  possesses  an  oxidizing  action,  the 
violet  color  of  the  permanganate  solution  will  be  quickly  destroyed. 

4.  Bleaching  Wool  with  Potassium  Permanganate. — This  com- 
pound is  also  a  strong  oxidizing  agent,  and  its  solution  will  rapidly  destroy 
the  natural  pigment  of  wool.  In  the  decomposition  of  the  permanganate, 
however,  whereby  it  liberates  oxygen,  there  is  also  formed  an  insoluble 
hydrated  oxide  of  manganese,  which  is  precipitated  in  the  wool  and  imparts 
to  it  a  brown  color.  The  decomposition  (or  oxidizing  action)  of  the  per- 
manganate is  facilitated  by  the  presence  of  sulphuric  acid,  and  the  bleach- 
ing effect  is  completed  in  a  relatively  short  space  of  time.  In  order  to 
remove  the  insoluble  brown  compound  of  manganese  from  the  fiber  it 
is  best  to  treat  the  material  in  a  cold  dilute  solution  of  sodium  bisulphite. 
The  sulphurous  acid  present  in  the  latter  solution  reacts  with  the  man- 
ganese compound  to  form  a  colorless  soluble  product,  and  the  fiber  is 
left  in  a  clear  white  condition.  Care  must  be  taken  in  this  connection 
not  to  employ  an  excess  of  sodium  bisulphite  solution,  otherwise  sulphurous 
acid  will  be  left  in  the  wool,  and  will  exhibit  the  defect  already  noted  under 
the  consideration  of  the  sulphurous  acid  bleach.  If  this  latter  defect 
is  avoided,  the  permanganate  bleach  on  wool  is  probably  as  satisfactory 
as  the  peroxide  bleach.  It  can  also  be  carried  out  in  much  less  time. 
Too  strong  a  solution  of  permanganate  must  be  avoided,  otherwise  the 
wool  will  acquire  a  harsh  feel,  due  to  the  oxidation  of  the  fiber. 


BLEACHING  WITH  PERiMANGANATE  113 

The  bleaching  bath  of  potassium  permanganate  may  be  prepared  as 
follows:  For  100  lbs.  of  material  use 

300  gallons  of  pure  water, 

2  lbs.  of  potassium  permanganate  crystals. 

Steep  in  the  cold  bath  for  one  hour,  then  squeeze  and  pass  into  a  fresh 
bath  containing 

300  gallons  of  water, 

7  gallons  of  sodium  bisulphite  sol.  (32°  Tw.), 
6  pints  of  oil  of  vitriol. 

Steep  in  the  cold  bath  for  two  hours,  then  squeeze  and  rinse.  The  tinting 
is  conducted  in  the  same  manner  as  for  the  other  methods  of  bleaching. 
The  permanganate  bath,  as  a  rule,  cannot  be  used  over  again  by  replen- 
ishing, as  the  permanganate  salt  becomes  decomposed  and  loses  its  bleach- 
ing efficiency. 

With  regard  to  the  comparative  cost  of  the  several  methods  of  bleach- 
ing wool,  it  may  be  stated,  in  general,  that  the  sulphurous  acid  bleach 
is  the  cheapest,  while  the  peroxide  method  is  the  highest.  An  approxi- 
mation to  the  comparative  cost  of  the  three  methods  (for  yarn)  is  as 
follows : 

Sulphur  bleach  (gas) If  cts.  per  lb. 

Permanganate  bleach 2^  cts.  per  lb. 

Peroxide  bleach 4|  cts.  per  lb. 

The  permanganate  method  has  not  come  into  favor  as  yet,  apparently 
on  account  of  it  being  more  difficult  to  regulate. 

5.  Bleaching  Silk. — The  pure  fiber  of  silk  is  remarkably  white  in 
appearance,  and  will  only  require  bleaching  in  special  cases,  as  when  a 
snow-white  fabric  is  desired.  Soupled  and  ecru  silk,  not  having  all  of 
the  silk-glue  removed  will  contain  more  or  less  coloring  matter,  and  especi- 
ally if  of  the  yellow-gum  variety.  Such  silk  is  frequently  bleached  as 
an  operation  in  scouring,  dilute  solutions  of  aqua  regia  often  being  used 
(see  p.  99).  Tussah  silk  is  of  a  rather  dark  brown  color  which  it  does  not 
altogether  lose  even  after  complete  boiling-off.  Owing  to  the  difficulty, 
however,  of  bleaching  this  silk  satisfactorily  it  is  usually  left  in  its  natural 
color,  which  thus  becomes  a  distinctive  characteristic  of  this  class  of  silk. 

Silk  may  be  bleached  in  practically  the  same  manner  as  wool.  The 
sulphur  or  stoving  process  may  be  used  as  described  on  page  108,  the 
dampened  silk  being  hung  in  the  sulphur  chamber  overnight.  This 
method,  however,  has  all  the  objections  already  referred  to  under  the 
bleaching  of  wool;  that  is  to  say,  it  is  not  permanent,  and  the  retention 
of  even  traces  of  the  sulphurous  acid  by  the  fiber  causes  difficulties  in 


114  BLEACHING  OF  WOOL  AXD  SILK 

dyeing  subsequently.  On  this  account  the  most  approved  method  of 
bleaching  silk  at  the  present  time  is  by  the  use  of  either  hj^drogen  j^eroxide 
or  sodium  peroxide.  The  action  in  both  cases  is  practically  the  same, 
though  the  latter  is  considerably  cheaper.  Sometimes  the  use  of  hydro- 
gen peroxide  is  preferred  as  no  metallic  salts  are  then  introduced  into 
the  bath,  as  would  be  the  case  when  sodium  peroxide  is  used.  When 
hydrogen  peroxide  is  employed  the  silk  is  steeped  for  eight  to  ten  hours 
(generally  overnight)  in  a  solution  containing  2  to  3  gallons  of  hydrogen 
peroxide  (12  vols.),  |  to  1|  pints  of  sodium  silicate,  and  1  lb.  white  soap 
(previously  dissolved),  and  10  gallons  water.  The  bath  is  maintained  at 
about  120°  F.  during  the  bleaching.  After  coming  from  the  bleaching 
bath  the  silk  is  rinsed  first  in  a  bath  containing  a  small  amount  of  sul- 
phuric acid,  and  then  with  fresh  water.  When  bleaching  with  sodium 
peroxide  the  bath  is  prepared  and  used  in  the  same  manner  as  described 
for  wool  (see  p.  110). 

6.  Experimental.  Exp.  28.  Bleaching  Wool  by  Tinting. — Take  a  well-scoured  test 
skein  of  woolen  ,varn  and  work  in  a  lukewarm  bath  containing  a  trace  of  oxalic  acid  and 
a  trace  of  Acid  Violet  2  B  (about  ^oo  per  cent  on  the  weight  of  the  wool  will,  as  a  rule,  be 
ample  dyestuff).  Take  great  care  not  to  add  too  much  of  the  coloring  matter,  other- 
wise too  distinct  a  color  will  be  imparted  to  the  wool.  After  tinting,  squeeze  and  dry. 
It  will  be  found  that  the  violet  coloring  matter  has  neutralized  the  yellowish  tint  of  the 
wool,  so  that  the  material  seems  whiter  than  before.  To  show  the  same  operation  on 
cotton,  take  a  test  skein  of  cotton  yarn  which  has  been  well  scoured  out  with  2  per  cent 
of  Monopol  oil,  and  work  it  in  a  dilute  lukewarm  soap  bath  containing  a  trace  (about 
■^Ijj  per  cent  on  the  weight  of  the  cotton)  of  ]Methyl  Violet  5  B.  Then  squeeze  and  dry. 
It  will  be  found  that,  as  with  the  wool,  the  skein  of  cotton  will  appear  whiter  after  tinting, 
owing  to  the  fact  that  the  violet-blue  color  has  destroyed  the  yellowish  color  of  the 
natural  fiber. 

Exp.  29.  Bleaching  Wool  with  Sulphurous  Acid  Gas. — Take  a  skein  of  well-scoured 
woolen  yarn,  wet  it  out  in  water,  then  squeeze  it  so  that  the  wool  is  left  only  moist; 
place  it  in  a  compartment  filled  with  sulphurous  acid  gae  for  twelve  to  twenty-four  hours. 
Then  wash  well  in  water,  and  then  in  a  bath  containing  a  trace  of  oxalic  acid  and  Acid 
Violet  for  tinting. 

Exp.  30.  Bleaching  Wool  with  Sodium  Bisulphite. — Prepare  a  bath  containing  300  cc. 
of  water  and  10  cc.  of  sodium  bisulphite  solution  (32°  Tw.).  Immerse  two  well-scoured 
skeins  of  woolen  yarn  in  this  bath,  work  well  for  about  fifteen  minutes,  then  allow  to 
soak  for  twelve  to  twenty-four  hours.  Then  squeeze  and  work  in  a  bath  containing  5 
per  cent  of  sulphuric  acid  (on  the  weight  of  the  wool).  Then  wash  the  first  skein  well  in 
water,  and  finally  in  a  bath  containing  a  trace  of  oxalic  acid  and  Acid  Violet  for  tinting. 
Then  squeeze  and  dry.  Take  the  second  skein  so  bleached  and  pass  through  a  cold 
bath  containing  a  couple  of  drops  of  a  dilute  solution  of  potassium  permanganate  (just 
sufficient  to  give  the  water  a  violet  color),  and  then  wash  again.  If  too  strong  a  solution 
of  the  potassium  permanganate  is  used  the  wool  will  acquire  a  brownish  color,  and  will 
have  to  be  passed  through  a  dilute  bath  of  sodium  bisulphite  in  order  to  remove  the 
brown  hydrate  of  manganese  which  will  be  precij^itated  on  the  fiber.  Cut  about  6  ins. 
from  each  of  the  two  bleached  skeins  and  plait  with  portions  of  a  skein  of  woolen  yarn 
which  has  been  dyed  with  Magenta  (a  dyestuff  quite  susceptible  to  the  action  of  sul- 
phurous acid),  and  allow  the  samples  thus  prepared  to  remain  for  several  days.     The 


EXPERIMENTAL  STUDIES  115 

skein  of  dyer]  yarn  may  easily  be  prepared  by  working  a  skein  of  woolen  yarn  in  a  bath 
containing  300  cc.  of  water  and  about  5  cc.  of  a  solution  of  Magenta  for  one^half  hour  at  a 
temperature  of  180°  F.  On  examination  after  a  time  it  will  be  found  that  the  bleached 
skein  wh  ch  was  not  treated  with  the  potassium  permanganate  solution  has  caused  a 
discoloration  of  the  dyed  sample  with  which  it  was  plaited,  whereas  the  other  bleached 
skein  has  not.  This  test  shows  the  presence  of  sulphurous  acid  in  the  former  and  the 
absence  of  it  in  the  latter. 

Exp.  31.  Bleaching  Wool  with  Sodium  Peroxide. — Prepare  a  bath  containing  300 
cc.  of  water  and  3  cc.  of  concentrated  sulphuric  acid;  then  carefully  add  with  constant 
stirring  4  grams  of  sodium  peroxide.  Test  with  litmus  paper,  and  if  not  acid  in  reaction, 
add  sufficient  dilute  sulphuric  acid  to  turn  the  paper  red.  This  will  neutralize  all  of  the 
caustic  soda  formed  in  the  decomposition  of  the  sodium  peroxide  with  the  water.  Now 
add  sufficient  sodium  silicate  solution  to  make  the  bath  slightly  alkaline;  that  is,  until 
it  turns  the  htmus  paper  blue  again.  Heat  the  bath  to  120°  F.,  when  it  is  ready  for 
bleaching.  Take  a  well-scoured  skein  of  woolen  yarn  and  work  it  in  this  bath  for 
fifteen  minutes,  and  then  allow  it  to  steep  under  the  liquor  for  twelve  to  fifteen  hours, 
maintaining  the  temperature  as  nearly  as  possible  at  about  100°  F.  during  that  time. 
Then  wash  well  and  squeeze,  and  finally  tint  in  a  bath  containing  a  trace  of  oxalic  acid 
and  Acid  Violet.     Then  squeeze  and  dry. 

Exp.  32.  Bleaching  Wool  with  Potassium  Permanganate. — Prepare  a  bath  con- 
taining 300  cc.  of  water  and  0.2  gram  of  potassium  permanganate  and  5  per  cent  (on  the 
weight  of  the  wool)  of  sulphuric  acid.  Warm  the  bath  to  100°  F.,  and  steep  a  well- 
scoured  skein  of  woolen  yarn  therein  for  about  five  minutes,  working  during  that  time. 
Then  rinse,  and  it  will  be  found  that  the  wool  has  become  brown  in  color  (this  is  due 
to  the  precipitation  of  hydrated  oxide  of  manganese  on  the  fiber,  resulting  from  the 
decomposition  of  the  potassium  permanganate) .  Next  work  the  skein  in  a  cold  bath 
containing  300  cc.  of  water  and  2  cc.  of  sodium  bisulphite  solution  (of  32°  Tw.).  The 
wool  will  rapidly  turn  white  as  the  brown  deposit  of  manganese  oxide  is  dissolved  by  the 
bisulphite  of  soda. 


CHAPTER   IV 
BLEACHING  OF  COTTON 

1.  General  Method  of  Cotton  Bleaching. — Ordinary  American  cotton 
is  of  a  comparatively  white  color  when  in  the  natural  raw  state;  but, 
nevertheless,  it  contains  a  small  amount  of  natural  pigment  matter  of  a 
yellowish  brown  color.  This  pigment  is  so  small  in  amount  that  it  does 
not  interfere  in  the  general  dyeing  of  cotton;  but  when  light,  delicate 
shades  are  desired  in  dj^eing,  or  when  the  cotton  material  is  to  be  left 
in  the  white  condition  for  sale,  it  is  usually  necessary  to  bleach  it. 
Cotton  in  the  loose  state  is  seldom  bleached,  since  the  bleaching  processes 
considerably  deteriorate  the  spinning  qualities  of  the  fiber  by  removing 
its  waxy  coating;  the  fiber  is  also  made  more  brittle  by  the  bleaching,  which 
causes  a  largely  increased  amount  of  waste  in  carding  and  spinning; 
furthermore,  after  bleached  cotton  is  passed  through  the  numerous  mechan- 
ical operations  of  carding  and  spinning  it  will  become  more  or  less  dis- 
colored and  will  have  acquired  considerable  dirt,  so  that  the  final  yarn  or 
cloth  would  be  unsatisfactory  as  a  bleached  product.  Yarn  is  sometimes 
spun  from  bleached  stock  for  the  manufacture  of  knit  goods,  thus  giving 
a  half-bleached  product;  it  is  also  used  for  half-bleached  filling  yarns. 
Cotton  yarn  is  frequent h^  bleached  both  for  the  purpose  of  being  dyed  in 
delicate  shades  and  of  being  manufactured  into  white  goods — more  espe- 
cially knitted  fabrics,  lace,  etc.  The  chief  form,  however,  in  w4iich  cotton 
is  bleached  is  that  of  cloth;  in  which  case  it  may  be  used  (a)  as  a  bleached 
bottom  for  the  dj'eing  of  delicate  shades  or  for  colors  such  as  Turkey  Red, 
(6)  for  print  cloth  in  the  many  processes  of  calico-printing,  and  (c)  for  the 
purpose  of  being  sold  in  the  white  state,  or  as  a  market-bleach. 

Though  a  number  of  chemical  agents  have  been  suggested  for  the 
bleaching  of  cotton,  those  which  have  been  most  successfully  and  exten- 
sively employed  are  chloride  of  lime  {bleaching  powder)  and  liquid  chlorine. 
The  effective  bleaching  agent  in  the  chloride  of  lime  is  chlorine  in  a  loosely 
combined  condition.  But  the  chlorine  itself  does  not  accomplish  the 
bleaching  in  a  direct  manner.  In  the  process  the  chlorine  is  liberated  in 
the  nascent  condition  in  the  presence  of  water;  the  latter  is  decomposed 
by  the  chlorine  yielding  hydrochloric  acid  and  nascent  oxygen,  and  it  is 

116 


PROCESS  IN  COTTON  BLEACHING  117 

this  oxygen  which  causes  the  bleaching  action.     The  chemical  reactions 
may  be  thus  represented : 

Chloride  of  lime  — ^  chlorine. 

Chlorine + water  — >  hydrochloric  a,cid-\- oxygen. 

Chlorine  of  itself  is  without  any  bleaching  action,  a  fact  which  has 
been  demonstrated  by  allowing  dry  chlorine  to  act  on  sensitive  colors,  the 
result  being  that  the  colors  were  not  destroyed.  Liquid  chlorine  as  a 
bleaching  agent  is  used  by  dissolving  the  gas  in  an  alkaline  solution  (soda 
ash,  caustic  soda,  or  a  mixture  of  the  two)  in  order  to  form  sodium  hypo- 
chlorite. This  solution  is  then  employed  in  practically  the  same  manner  as 
that  of  bleaching  powder. 

2.  The  Operations  in  Cotton  Bleaching. — There  are  five  distinct  opera- 
tions in  the  proper  bleaching  of  cotton : 

(1)  Boiling-ma;  this  is  really  a  scouring  operation,  the  object  of  which  is  to  remove 
all  the  waxy  and  resinous  matters  in  the  fiber. 

(2)  Treatment  with  bleaching  powder  solution;  this  is  for  the  purpose  of  destroying 
the  natural  coloring  matter  in  the  fiber,  and  also  for  the  brealving  down  of  various  non- 
cellulosic  matters  associated  with  the  cellulose  of  the  cotton. 

(3)  Treatment  with  a  dilute  solution  of  acid;  this  is  generally  termed  "  souring," 
and  is  for  the  purpose  of  dissolving  the  lime  compounds  in  the  fiber  left  from  the  bleach- 
ing powder  and  to  decompose  any  chlorine  compounds  which  may  have  been  formed. 

(4)  Washing;  this  is  for  the  purpose  of  removing  all  soluble  matters  resulting  from 
the  action  of  the  bleaching  powder  and  the  acid;  also  for  the  removal  of  the  acid  from 
the  fiber. 

(5)  Soaping  and  tinting;  this  is  for  the  purpose  of  neutralizing  the  last  traces  of  acid, 
and  also  for  softening  the  cotton.     The  tinting  is  to  give  a  slight  bluish  tone  to  the  white. 

3.  Boiling-out.^ — The  scouring  of  cotton  intended  for  bleaching  must 
be  carried  out  much  more  thoroughly  than  when  the  operation  is  merely 
for  the  purpose  of  wetting-out  the  cotton  previous  to  dyeing.  In  the  latter 
case  it  is  only  necessary  that  the  external  waxy  coating  on  the  fiber  be 
removed  or  softened  in  order  that  water  may  easily  impregnate  the  cotton. 
But  in  boiling-out  for  bleaching  it  is  required  to  remove  very  completely 
all  the  impurities  in  the  fiber,  including  the  waxy  coating,  the  miscel- 
laneous resinous  matters,  the  albuminous  substances,  and  in  fact  all  mat- 
ters of  a  non-cellulosic  character.  It  is  the  object  in  bleaching  to  obtain 
a  practically  pure  cellulose  for  the  bleached  cotton.  For  the  wetting- 
out  of  cotton,  a  dilute  solution  of  soap,  soda  ash,  or  soluble  oil  only  is 
required,  but  for  the  proper  boiling-out  of  the  cotton  a  rather  strong  solu- 
tion of  caustic  alkali  or  soda  ash  is  required ;  the  time  of  boiling  is  much 
prolonged  (usually  seven  to  ten  hours),  and  it  is  generally  conducted 
under  pressure  in  a  closed  kier. 

A  variety  of  methods  of  kier  boiling  may  be  employed.  An  open  kier 
system  may  be  used;   in  which  case  the  kier  consists  merely  of  a  round 


118  BLEACHING  OF  COTTON 

upright  tank  of  suitable  dimensions.  In  the  bottom  is  provided  a  per- 
forated false  structure  on  which  the  cotton  material  is  placed,  a  clear 
space  of  G  to  8  ins.  being  allowed  between  this  false  and  true  bottom  for  the 
accumulation  of  liquor  and  the  placing  of  steam  pipes.  The  cotton  goods 
(in  the  form  of  skeins,  warps,  woven  or  knit  cloth  as  the  case  may  be) 
are  packed  into  this  kier  systematically  so  as  to  avoid  possibility  of  tangling 
when  running  out.  The  packing  nuist  be  as  even  as  possible  so  as  to  pre- 
vent uneven  distribution  and  channeling  of  the  liquor  through  the  goods 
during  the  boiling.  The  goods  should  be  packed  into  the  kier  until  it  is 
about  five-sixths  filled  to  the  top,  then  a  perforated  wooden  cover  is 
clamped  down  on  the  material  so  as  to  hold  it  in  place.  To  facilitate  the 
wetting-out  of  the  cotton  in  the  kier  when  first  starting  to  boil,  it  is  best 
to  pass  the  goods  through  a  tank  of  hot  water  and  between  squeeze  rolls 
before  they  arc  run  into  the  kier.*  The  liquor  employed  for  boiling-out 
in  this  kier  is  usually  a  caustic  soda  solution,  containing  3  to  5  per  cent 
of  caustic  soda  on  the  weight  of  the  goods.  A  mixture  of  caustic  soda  and 
soda  ash  may  be  employed,  in  which  case  about  3  per  cent  of  each  ingredient 
is  used.  Silicate  of  soda  is  also  a  suitable  compound  to  use  in  the  boiling 
process,  4  to  6  per  cent  of  silicate  being  used  with  3  per  cent  of  caustic 
soda.  There  are  a  number  of  bleach  assistants  on  the  market  which  form 
very  good  boiling-out  agents,  and  these  as  a  rule  consist  of  various  mix- 
tures of  caustic  soda,  soda  ash,  and  silicate  of  soda.  For  the  handling  of 
small  quantities  of  material  it  is  sometimes  advantageous  for  the  bleacher 
to  buy  these  "  assistants,"  as  they  are  compounded  in  a  convenient  form 
for  ready  use.f 

An  all-important  point  in  the  proper  boiling-out  of  cotton  materials 
is  the  circulation  of  the  liquors  through  the  goods.     In  an  open  kier  this 

*  In  the  case  of  skein  yarn,  the  goods  are  usually  headed  up  in  the  form  of  small 
bundles  or  linked  together  in  a  continuous  chain.  Warp  yarn  is  usually  doubled  several 
times  or  chained  and  then  run  in  the  same  manner  as  cloth. 

t  There  has  been  a  tendency  among  some  dealers  in  chemicals  to  put  forward  the 
claim  that  the  presence  of  neutral  salts  in  the  alkalies  used  in  boiling-out  cotton  were  not 
detrimental  to  the  soda  boil.  This  claim  is  chiefly  for  the  purpose  of  covering  up  the 
impurities  which  may  be  found  in  their  caustic  soda  and  soda  ash,  and  these  impurities 
consist  principally  of  sodium  chloride  (common  salt)  and  sodium  sulphate  (glaubcrsalt). 
There  are  even  to  be  found  bleachers,  who  believe  that  the  addition  of  certain  small 
amounts  of  these  salts  to  the  boiling-out  mixture  is  beneficial.  To  arrive  at  the  truth 
in  the  case,  the  matter  has  been  carefully  investigated,  and  the  results  have  shown  that 
the  addition  of  common  salt  or  glaubcrsalt,  even  in  very  small  quantities,  produces  an 
inhibitory  effect  on  the  action  of  the  caustic  soda  in  properly  removing  the  impurities 
from  the  cotton  fiber,  and  this  effect  is  furthermore  a  very  notable  one.  The  color  of 
the  boiled  cotton  is  also  detrimentally  affected  by  the  presence  of  these  neutral  salts. 
The  effect  of  the  addition  of  sodium  phosphate  to  the  soda  boil  has  also  been  investigated, 
and  its  use  appears  to  be  almost  as  detrimental  as  that  of  the  other  two  salts  above  men- 
tioned. 


BOILING-OUT  OF  COTTON  119 

is  usually  effected  by  an  injector,  the  liquor  being  drawn  from  the  bottom 
of  the  kier  and  forced  around  to  the  top,  where  it  is  distributed  over  the 
goods  by  the  perforated  cover.  The  liquor  is  raised  to  the  boiling  point 
by  steam  blown  through  a  perforated  pipe  in  the  bottom  compartment  of 
the  kier.  In  the  open  kier  it  will  require  boiling  for  ten  to  twelve 
hours  to  bring  the  cotton  to  the  proper  condition.  It  also  requires  the 
use  of  a  large  amount  of  steam  both  for  the  heating  and  the  circulation  of 
the  liquor,  and  of  this  steam  a  vast  amount  goes  to  waste  in  the  open  air. 
On  this  account  open  kier  boiling  cannot  be  recommended  as  an  econom- 
ical process.  The  prolonged  treatment  which  is  necessary  is  also  liable 
to  bring  damage  to  the  goods  in  many  ways. 

Another  method  for  the  boiling-out  of  cotton  goods  is  to  use  a  closed 
or  pressure  kier.  There  are  a  number  of  types  of  these  kiers  on  the 
market.  In  one  form  of  kier  the  circulation  is  maintained  by  a  steam 
injector.  A  pressure  of  12  to  16  lbs.  is  usually  maintained  in  the  kier 
during  the  boiling.  The  time  required  to  complete  the  boiling-out  is 
eight  to  ten  hours,  and  the  usual  chemicals  already  mentioned  as  being 
used  in  the  open  kier  are  employed,  about  3  per  cent  of  caustic  soda  or 
its  equivalent  in  other  compounds  being  used.  In  another  form  the  cir- 
culation is  brought  about  by  a  vacuum  chest  operated  by  high  pressure 
steam.  The  pressure  in  the  kier  is  maintained  at  10  to  12  lbs.,  and  the 
time  of  boiling  is  reduced  under  usual  conditions  to  about  four  hours. 
The  amount  of  chemicals  required  for  this  form  of  kier  is  said  to  be  less 
than  for  other  types,  a  good  boiling-out  combination  being  2  per  cent  of 
caustic  soda  and  1  per  cent  of  solvine  or  other  soluble  sulphated  oil. 
The  use  of  the  oil  leaves  the  goods  much  softer  and  cleaner  in  appearance 
than  when  alkalies  alone  are  employed.  This  is  due  to  the  fact  that  the 
resinous  matters  in  the  fiber  are  readily  soluble  in  the  oil  and  are  thus 
easily  removed  from  the  fiber.* 

*  As  to  the  physical  changes  brought  about  in  the  cotton  yarn  by  reason  of  the  boiling- 
out  process,  carefully  conducted  experiments  have  shown  that  the  loss  in  weight  (allow- 
ing for  the  same  "  condition  "  of  the  yarn  before  and  after  boiling-out)  is  from  4  to  5 
per  cent,  depending  somewhat  on  the  count  of  the  yarn  and  the  nature  of  the  cotton. 
The  shrinkage  in  length  of  the  yarn  due  to  the  boiling-out  varies  considerably  with  the 
conditions,  but  an  average  loss  calculated  from  the  large  series  of  observations,  amounts 
to  2.6  per  cent.  In  commercial  bleaching  operations  it  is  customary  to  allow  about  5 
per  cent  shrinkage,  but  this  is  seldom  actually  reached.  Both  the  loss  in  weight  and 
loss  in  length  affect  the  true  count  of  boiled-off  yarn ;  a  large  number  of  tests  have  been 
made  on  this  subject,  and  the  following  table  exhibits  the  results.  The  "  true  "  count  of 
the  yarn  is  given  in  each  case : 

Count  before         Count,  after 
Boiling.  Boiling. 

24  25.7 

32  33 . 7 

40  42 . 0 

70  72.6 


Count  before 
Boiling. 

Count  after 
Boiling. 

80 

83.9 

100 

104.6 

120 

125.6 

150 

167.5 

120 


BLEACHING  OF  COTTON 


Whatever  system  of  l)oiling-oiit  is  employed,  it  is  necessary  to  wash 
out  the  goods  thoroughly  after  the  kier  treatment  with  the  alkaUne  Uquors. 
This  is  usually  accomplished  by  circulating  wash  waters  through  the  goods 
while  they  are  still  in  the  kier.  The  washing  is  a  necessary  process,  and 
its  purpose  is  to  remove  all  the  dirty  alkaline  liquor  from  the  cotton 
together  with  all  the  associated  impurities  contained  in  these  hquors.  If 
the  wasliing  is  mipcrfect,  kier  stains  will  be  left  on  the  goods. 


Fig.  93. — Eleachin^  Kier.     (Dehaitre  System.) 

This  very  thorough  boiling-out  of  the  cotton  previous  to  bleaching  is 
necessitated  by  the  fact  that  if  any  resinous  matters  (or  so-called  pectin) 


If  the  boiling-out  process  has  been  properly  conducted  there  should  be  a  slight  increase 
in  the  tensile  strength  of  the  yarn;  this  rather  anomalous  condition  is  caused  by  the 
felting  and  thickening  of  the  fibers.  It  may  be  stated  as  a  general  rule  that  any  differ- 
ence in  the  breaking  strength  between  unbleached  and  bleached  yarn  is  due  to  the 
bleaching  process,  and  is  not  caused  by  the  boiling-out,  provided,  of  course,  that  this 
latter  operation  has  been  j)roperly  conducted. 

Another  phj'sical  property  of  the  yarn  which  is  affected  by  the  boiling-out  process  is 
the  twist.  The  boiling  of  the  j'arn  causes  an  increase  in  the  number  of  turns  per  inch 
in  the  twist;  this,  of  course,  is  due  to  the  combined  effect  of  shrinkage  and  tightening 
of  the  yarn.  From  actual  data  on  this  subject  the  average  increase  in  the  twist  is  shown 
to  amount  to  about  15  per  cent. 


THE  LIME  BOIL 


121 


are  left  in  the  fiber,  the  bleached  material  will  gradually  become  yellow  on 
exposure  to  light  and  air.  Formerly  lime  was  very  generally  used  for  the 
boiling-out  of  cotton,  in  which  case  it  was  necessary  to  pass  the  material 
afterwards  through  an  acid  bath  (so-called  gray  sour)  to  remove  particles 
of  lime  which  might  otherwise  ''  burn  "  the  fiber.     It  was  thought  that 


Fig.  94. — Plate  Singeing  Machine. 


boiling  with  lime  caused  a  more  perfect  decomposition  and  removal  of 
the  resinous  substances  in  the  cotton.*     Lime,  however,  is  not  so  much 

*  In  treating  with  hme  the  process  in  brief  was  as  follows:  Freshly  slaked  quicklime 
was  made  up  with  water  into  milk-of-lime,  through  which  the  cloth  was  passed,  so  that 
it  became  well  saturated  with  the  liquor.  From  the  liming  machine  the  goods  were 
run  into  the  kier  for  boiling.  Though  the  amount  of  lime  used  varied  in  different  works 
and  with  different  kinds  of  goods,  on  the  average  about  5  to  7  lbs.  of  dry  lime  were  used 
per  100  lbs.  of  cotton  cloth.  The  necessity  for  the  gray  sour  after  a  lime  boil  is  due  to 
the  fact  that  insoluble  lime  soaps  are  formed  in  the  cloth  from  the  fatty  and  pectin 
matters  of  the  cotton.  These  would  not  be  removed  by  subsequent  washing,  but  require 
to  be  first  decomposed  by  acid  into  soluble  compounds,  or  rather  into  compounds  that 


122  BLEACHING  OF  COTTON 

used  at  tlio  present  tinio,  it  being  replaced  by  caustic  soda,  the  action  of 
which  is  more  efficient  and  requires  less  time.  When  the  lime  boil  is  used 
(chiefly  with  piece-goods)  a  previous  boiling  with  resin  soap  is  usually 
given.  Silicate  of  soda  is  a  very  good  alkaU  for  boiling-out  cotton  for 
bleaching.  Many  popular  "  bleach  assistants  "  consist  of  varj-ing  pro- 
portions of  silicate  of  soda,  soda  ash,  and  caustic  soda.*  Silicate  of  soda 
does  not  give  the  cotton  such  a  harsh  feel  as  when  caustic  soda  is  used.f 

4.  Bleaching  with  Hypochlorites. — After  the  goods  have  been  boiled- 
out  and  washed  tlie  next  process  is  treatment  with  the  bleaching  liquor. 
The  method  of  handling  the  goods  in  this  process  will  determine  the  strength 

are  readily  removed  by  washing.  It  is  claimed  by  some  that  hme  boiling  is  less  Hable 
to  give  kicr  stains  on  the  cloth  than  when  the  soda  boil  is  used,  but  bj'  the  use  of  proper 
care  and  the  addition  of  soluble  oil  to  the  soda  boil,  kier  stains  maj'  usuallj'  be  prevented. 
The  use  of  soft  clean  water  is  also  an  aid  in  this  respect.  Furthermore,  in  washing  the 
goods  in  the  kier  after  the  soda  boil  hot  water  should  be  used,  as  if  cold  water  is  brought 
into  contact  with  the  freshlj'  boiled  goods  the  pectin  matters  will  be  thrown  out  of  solu- 
tion and  possibly  stain  the  goods.  These  stains  maj'  usually  be  cleared  up  bj-  running 
the  goods  through  a  dilute  acid  bath  (hydrochloric  or  sulphuric  acid  of  1°  Tw.  at  100°  F.) 
and  then  straightway  into  the  bleach. 

*  Some  bleach  assistants  contain  glaubersalt  and  other  neutral  salts  added  to  the 
caustic  alkali,  and  it  is  even  claimed  that  the  presence  of  these  neutral  salts  increa.ses 
the  efficiency  of  the  alkali.  This,  however,  has  been  disproved,  for  it  has  been  shown 
(Trotman,  Jour.  Soc.  Chem.  Ind.,  1910,  p.  249),  that  the  addition  of  such  salts  in  all 
cases  produced  a  decreased  effect  in  the  action  of  the  caustic  soda  on  the  cotton. 

t  Investigations  have  been  made  into  some  of  the  conditions  of  the  boiling-out  of 
cotton  yarns.  Thoroughly  boiled-off  cotton  yarn  has  been  shown  to  contain  less  than 
0.15  per  cent  of  fattj-  matters  and  less  than  0.10  per  cent  of  nitrogen;  yarn  showing  the 
presence  of  greater  amounts  of  these  constituents  indicate  a  faulty  boiling-oflf.  As  to 
the  alkaline  agents  emi)loyed  for  the  boiling-out  process  it  has  been  found  that  caustic 
potash  removes  the  greatest  amount  of  impurities  and  in  the  shortest  time;  from  a 
series  of  experiments  on  this  matter  it  has  been  demonstrated  that  when  employed 
in  equivalent  quantities,  caustic  potash  will  remove  about  20  per  cent  more  impurities 
from  the  cotton  in  the  same  time.  The  relative  values  of  the  different  alkalies  emploj-ed 
are  given  in  the  following  table,  which  represents  the  amount  of  impurities  removed 
from  the  fiber  in  what  is  supposed  to  be  a  complete  boiling-out  operation: 

Per  Cent  Loss. 

Caustic  potash 5 .  00 

Caustic  soda 4 .  40 

Sodium  carbonate 3 .  70 

Sodium  borate  (borax) 2 . SO 

Sodium  silicate 2  40 

The  chief  u.se  of  the  sodium  carbonate  in  the  boi!ing-out  mixture  is  as  an  emulsifier, 
as  this  alkali  does  not  readily  cause  saponification  of  the  fatt}-  matters  in  the  cotton. 
The  same  remark  is  also  true  of  sodium  borate  (borax),  though  its  power  in  this  respect 
is  considerably  less.  It  will  be  noted  that  sodium  silicate  has  the  least  scouring  effect, 
and  there  is  a  possibility'  of  this  alkali  suffering  decomposition  during  the  boiling-out 
process  with  the  result  that  silica  is  deposited  on  the  goods;  on  this  account  its  use  has 
Dot  been  recommended  ou  fine  goods. 


SINGEING  MACHINES 


123 


Fig.  95. — Two-Burner  Gas  Singeing  Machine.     (Mather  &  Piatt). 


Fig.  96.— Diagram  of  Gas  Singeing  Machine. 


124 


BLEACHING  OF  COTTON 


of  chemic  to  cmplo}'.  The  usual  process  for  cloth  is  to  pass  the  material 
through  a  "  chemic  "  box  containing  the  bleach  liquor  and  provided 
with  squeeze  rolls,  so  that  the  goods  are  well  padded  with  the  liquor  and 
retain  about  their  own  weight  of  the  solution. 

The  cloth  is  then  folded  down  into  suitable  boxes  *  and  allowed  to 
stand  exposed  to  the  air  and  light  for  one  to  three  hours,  depending 
on  the  degree  of  bleaching  desired.  In  this  continuous  process  of  treat- 
ment the  strength  of  bleaching  powder  f  solution  is  generally  about 
2|  to  4°  Tw.  After  the  goods  have  whitened  up  to  the  proper  point 
thej^  are  run  in  the  same  continuous  manner  through  another  tank  pro- 
vided with  running  water  for  the  purpose  of  washing  out  the  lime  from  the 
cloth.     From  the  washing  tank  the  goods  then  pass  directly  to  a  third 


Fig.  97.— Five-Burner  Gas  Singe,  Tulpin  Style.     (H.  W.  Butterworth  &  Sons  Co.) 


tank  containing  a  solution  of  anti-chlor.  The  amount  of  this  chemical 
required  will  depend  of  course  on  the  strength  of  the  chemic  originally 
employed,  but  usually  from  3  to  5  per  cent  of  the  weight  of  the  goods 
will  be  necessary.     Anti-chlor  consists  of  bisulphite  of  soda  in  solution 

*  These  usually  consist  of  large  wooden  or  concrete  tanks. 

t  If  sodium  hypochlorite  solution  is  used  (prepared  from  liquid  chlorine  and  alkali, 
from  bleaching  powder  and  soda  ash,  or  from  the  electrolysis  of  salt)  the  strength  of  the 
chemic  should  be  about  one-half  that  of  bleaching  powder  in  terms  of  the  content  of 
active  chlorine.  That  is  to  say,  bleaching  powder  solution  of  3°  Tw.  represents  a  con- 
tent of  about  85  grams  per  liter  of  active  chlorine;  so  the  sodium  hypochlorite  solution 
should  be  of  a  strength  to  represent  about  4^  grams  per  liter  of  active  chlorine.  The 
density  of  the  liquor  should  not  necessarily  be  taken  as  a  criterion,  as  this  may  not  rep- 
resent at  all  accurately  the  real  bleaching  activity,  but  may  vary  with  the  presence  of 
dissolved  salts. 


ACTION  OF  BLEACHING  POWDER 


125 


and  it  possesses  the  property  of  neutralizing  chlorine  compounds  and 
thus  removing  them  from  the  fiber.  Instead  of  using  anti-chlor  it  is 
also  possible  to  employ  a  dilute  solution  of  sulphuric  acid.  A  solution  of 
about  1°  Tw.  is  the  customary  strength. 

3.  Bleaching  Powder  and  its  Use. — Bleaching  powder  or  chloride  of 
lime  is  prepared  by  treating  slaked  lime  with  chlorine  gas.     Its  chemical 

/OCl 
formula  is  Ca<^         ,  or  CaOCl2.     It  is  commonly  known  as  "  chemic  " 

\C1 
or  "  bleach."     Chloride  of  lime  is  a  yellowish  white  powder  which  smells 
strongly  of  chlorine,  especially  if  moistened.*     When  treated  with  water 
it  partly  goes  into  solution  and  partly  forms  a  bulky  white  precipitate  con- 


^,l,v...^^l..■^^v....l.,v^V..^^^■J:'■^C^T^'.V■^ 


Fig.  98. — Stirring  Arrangement  for  Dissolving  Bleaching  Powder.     (Zipser.) 


sisting  for  the  most  part  of  lime  (CaO).  The  solution  has  a  yellowish 
color  and  is  the  liquid  employed  for  the  preparation  of  the  bleaching  bath. 
A  good  quality  of  chloride  of  lime  should  contain  about  36  per  cent  of 
available  chlorine,  that  is  to  say,  chlorine  which  is  active  in  the  bleaching 
process.  The  exact  chemical  reactions  which  take  place  in  the  use  of 
chloride  of  lime  are  not  thoroughly  understood,  though  they  have  been 
the  subject  of  much  investigation.  It  is  probable  that  when  chloride  of 
lime  is  dissolved  in  water,  calcium  chloride  (CaCl2),  hypochlorous  acid 
(HCIO),  and  calcium  oxide  (CaO;  are  formed,  as  follows: 

2CaOCl2+H20  =  CaCl2+2HC10+CaO. 

*  Exposure  to  the  action  of  carbon  dioxide  also  causes  the  evolution  of  chlorine  from 
both  bleaching  powder  and  its  solutions  (see  Taylor,  Jour.  Soc.  Dyers  and  Col.,  1910, 
p.  115).  This  effect  of  carbon  dioxide  has  not  generally  been  recognized  by  bleachers  in 
practice,  it  usually  being  considered  that  carbonic  acid  causes  the  formation  of  hypo- 
chlorous  acid  when  acting  on  solutions  of  bleaching  powder. 


126 


BLEACHING  OF  COTTON 


Hence  the  bleaching  Hquor,  as  used,  may  be  considered  as  a  solution  of 
hypochlorous  acid;  the  calcium  chloride  produces  no  effect  in  bleaching,* 
No  doubt  a  portion  of  the  lime  also  remains  in  solution  as  calcium  hypo- 
chlorite (Ca(0Cl)2).  The  insoluble  calcium  oxide  is  filtered  off  (or  settled 
out)  before  the  bleaching  Hquor  is  used.  Hypochlorous  acid  is  a  very 
unstable  substance  (espcciall}''  in  the  presence  of  organic  matter,  such  as 
the  fibers),  and  it  readily  decomposes  into  water  and  an  oxide  of  chlorine 
(CI2O),  as  follows: 

2HC10  -^  H2O+CI2O. 


Fig.  99.— Chemic  Box. 


The  latter  is  a  strong  oxidant,  as  it  splits  up  into  chlorine  and  free  oxygen. 

CI2O  ->  CI2+O. 

The  chlorine  thus  liberated  reacts  with  the  water  present  to  form  hj^dro- 
chloric  acid  and  another  portion  of  free  oxj'gcn : 

Cl2  +  H20  =  2HC1  +  0. 

*  The  effect  of  the  calcium  chloride  in  the  bleaching  bath  is  obscure.  It  is  claimed, 
however,  to  be  beneficial.  The  addition  of  common  salt  to  the  bleaching  liquor  has  l)cen 
recommended  as  increasing  the  efhciency  of  ihe  bleaching.  The  exact  mechanism  of  its 
action  is  not  known. 


PREPARATION  OF  BLEACHING  SOLUTION 


127 


Under  certain  conditions  it  is  probable  that  the  hypochlorous  acid  decom- 
poses directly  into  hydrochloric  acid  and  oxygen: 

HCIO  -^  HCl+0. 

Solutions  of  bleaching  powder  are  best  prepared  by  first  grinding  the 
powder  with  a  small  quantity  of  cold  water  until  a  thin  uniform  paste  is 


'  \  /    \ 


Fig.  100. — Chemic  and  Souring  Box. 


obtained,  and  then  diluting  with  cold  water  and  allowing  to  settle  until 
the  liquor  is  clear.  A  concentrated  solution  of  bleaching  powder  will 
show  a  density  of  about  18°  Tw.  For  the  preparation  of  the  bleaching 
bath  this  is  diluted  to  about  2°  Tw.  Care  should  be  taken  that  no  undis- 
solved particles  of  bleaching  powder  pass  into  the  bleaching  bath,  other- 
v/ise  the  cotton  may  become  tendered  in  spots.  It  is  also  necessary  that 
the  material  be  completely  immersed  in  the  solution  during  the  bleaching, 


128  BLEACHING  OF  COTTON 

for  under  the  influence  of  the  oxygen  of  the  air  the  bleaching  Uquor  will 
seriously  weaken  the  cotton.  The  temperature  of  the  bleaching  bath 
should  alwaj's  be  cold;  it  is  only  in  exceptional  cases  where  low-grade 
material  is  treated  that  the  bleaching  liquor  is  ever  warmed,  and  even  then 
only  to  about  100°  F.  The  time  of  immersion  of  the  cotton  in  the  bleach- 
ing solution  should  be  from  one-half  to  one  hour;  too  long  a  treatment 
will  cause  a  tendering  of  the  fiber. 

6.  The  Acid  Treatment. — When  the  cotton  comes  from  the  solution 
of  bleaching  powder  it  contains  a  considerable  amount  of  lime  compounds, 
partly  as  calcium  hj^pochlorite  and  partly  as  calcium  oxide;  there  is  also 
present  calcium  chloride.  The  acid  treatment  (generally  known  as  "  sour- 
ing ")  is  for  the  purpose  of  decomposing  the  calcium  hypochlorite  and  the 
calcimn  oxide: 

Ca(OCl)2+H2S04  =  CaS04+2HC10. 
CaO-FH2S04  -  CaS04+H20. 

In  the  first  case  Lypochlorous  acid  is  formed  which  furthers  and  com- 
pletes the  bleaching.  In  both  cases  calcium  sulphate  (gypsum)  is  formed 
as  a  white,  fitnelj^  divided,  though  insoluble,  powder.  This  is  quite  easily 
removed  from  tlie  fiber  by  subsequent  washing,  and  being  of  a  very  neutral 
character,  has  no  action  on  the  cotton.  As  a  rule,  the  cotton  comes  up 
much  whiter  after  the  souring,  and  the  evolution  of  free  chlorine  gas  is 
very  evident.  The  souring  is  usually  done  in  a  cold  bath  of  sulphuric  acid 
of  1°  Tw.  density.  Stronger  solutions  are  not  advisable,  as  they  are  liable 
to  weaken  the  cotton.  Hydrochloric  acid  may  be  used  to  replace  the 
sulphuric,  in  which  case  calcium  chloride  will  be  formed,  which  is  a  very 
soluble  salt  and  is  more  easily  removed  from  the  fiber  than  the  insoluble 
calcium  sulphate.  To  obtain  an  equivalent  acid  strength  about  2.25 
parts  by  weight  of  hydrochloric  acid  should  be  used  for  1  part  by  weight  of 
sulphuric  acid.  In  case  the  boiling-out,  bleaching,  etc.,  are  carried  out 
in  machines  containing  copper  or  bronze  a  small  amount  of  copper  salt 
will  be  formed  which  with  sulphuric  acid  will  produce  an  insoluble  precip- 
itate of  a  double  sulphate  of  copper  and  calcium.  This  will  become 
fixed  in  the  cotton  and  is  very  difficult  to  remove.  If  hydrochloric  acid, 
however,  is  used,  no  insoluble  precipitate  will  be  formed,  and  the  copper 
salt  is  easily  washed  awa}^ 

7.  Washing. — Immediately  following  the  souring  the  cotton  should 
be  thoroughly  washed  with  fresh  water  in  order  to  remove  as  far  as  possible 
all  of  the  acid.  Should  the  washing  be  delayed  for  any  length  of  time  there 
is  danger  of  portions  of  the  bleached  material  becoming  dry,  which  will 
cause  tender  spots  to  form.  The  washing  should  be  continued  until  the 
presence  of  acid  is  no  longer  evident;   this  may  be  shown  by  testing  the 


AFTER-TREATMENT  OF  BLEACHED  COTTON 


129 


cotton  with  a  piece  of  blue  litmus  paper,  which  will  turn  red  if  any  acid  is 
present.  The  washing  is  also  for  the  purpose  of  removing  the  sulphate 
of  calcium  which  is  precipitated  in  the  cotton  during  the  souring.  The 
chlorine  which  is  generated  in  the  material  during  the  same  process  is 
also  removed  by  the  washing,  and  care  should  be  taken  to  eliminate  it 
very  thoroughly,  otherwise  the  cotton  will  subsequently  be  weakened  by 
over-oxidation  and  the  formation  of  acid  in  the  fiber.  The  presence  of 
chlorine  in  the  cotton  may  be  tested  for  by  a  mixed  solution  of  potassium 


Fig.  101. — Bleach  House  Washer.     (Textile-Finishing  Machinery  Co.) 


iodide  and  starch  paste,  which  will  give  a  blue  color  with  a  trace  of  chloride. 
This  test  depends  on  the  fact  that  chlorine  liberates  iodine  from  potassium 
iodide,  and  the  free  iodine  combines  with  the  starch  to  form  a  compound 
with  an  mtensely  blue  color. 

8.  Soaping  and  Tinting. — The  final  operation  essential  to  the  bleaching 
of  cotton  is  that  of  soaping.  For  this  purpose  the  material  is  treated  in 
a  dilute  lukewarm  solution  of  soap.  The  latter  should  be  of  good  quality 
and  free  from  any  ingredients  liable  to  cause  discolorations  in  the  dried 
and  finished  bleach.     The  object  of  the  soaping  is  primarily  to  soften  the 


130 


BLEACHING  OF  COTTON 


cotton,  which  will  have  acquired  considerable  harshness  in  the  boiling-out, 
bleaching,  and  acid  treatments.  It  also  has  the  purpose  of  neutralizing 
absolutely  all  trace  of  acid  in  the  cotton,  and  thus  preventing  subsequent 
tendering.  In  the  soap  bath  it  is  also  customary  to  add  a  small  quantity 
of  a  blue  dyestuff,  such  as  Cotton  Blue,  Methylene  Blue,  Soluble  Prussian 
Blue  (bleacher's  tint),  etc.,  for  the  purpose  of  tiJiting  the  bleached  white 
to  a  satisfactory  bluish  tone.  In  case  a  cream  white  bleach  is  desired, 
the  tinting  is  omitted.  Care  must  be  had  not  to  tint  the  cotton  too 
strongly,  otherwise  the  material  will  appear  dull  and  dirty. 


Fig    102. — Bleach  House  Squeezer.     (Textile-Finishing  Machinery  Co.) 

In  the  entire  process  of  bleaching,  the  cotton  will  lose  in  weight  about 
5  to  7  per  cent.  If  properly  bleached  the  loss  in  tensile  strength  should 
not  be  over  5  per  cent.  The  elasticity  will  be  somewhat  less  than  that  of 
the  unbleached  cotton.  The  tendering  of  cotton  in  bleaching  may  be  due 
to  several  causes: 

(1)  Oxidation  caused  by  exposure  to  the  air  during  the  boiling-out  process.  If  a 
skein  of  cotton  yam  is  so  hung  as  to  be  partly  suspended  in  a  solution  of  caustic  soda 
and  boiled  thus  for  some  time,  it  will  be  found  to  be  seriously  weakened  at  that  part 
where  it  comes  into  contact  simultaneously  with  the  alkaline  liquor  and  the  air. 

(2)  Oxidation  due  to  the  use  of  too  strong  a  solution  of  bleaching  powder,  or  to  its 
becoming  overheated. 

(3)  The  drying  of  acid  in  the  fiber  or  of  particles  of  lime  from  sediment  in  the  bleach- 
ing bath. 


TEST  FOR  OXY-CELLULOSE 


131 


The  oxidation  of  cotton  leads  to  the  formation  of  a  substance  known 
as  oxijceUuIose,  which  is  structureless  and  friable  in  character,  hence  its 
formation  leads  to  a  weakening  of  the  fiber.  The  presence  of  oxycellulose 
may  usually  be  recognized  by  staining  the  cotton  with  a  dilute  solution 


Fig.  103— Bleach  Vat  for  Warps  and  Skeins. 

of  Methylene  Blue;  ordinary  cotton  has  but  slight  affinity  for  this  colormg 
matter,  whereas  oxycellulose  is  strongly  dyed. 

9  Use  of  "  Anti-chlor."-As  the  perfect  removal  of  the  chlorme  from 
the  cotton  is  very  difficult  by  simply  washing  with  water,  it  is  sometimes 
expedient  to  neutralize  the  free  chlorine  with  a  suitable  chemical  agent^ 
The  chief  substances  used  as  "  anti-chlors  "  are  sodium  hyposulphite 


132 


BLEACHING  OF  COTTON 


Fici.  104— Ex)ller  Washing  Machine.     (Mather  &  Piatt.) 


Fig  .  1 05  .—Six-Compartment  Open  Washer  or  Soaper.     (Textile-Finishing  Machinery  Co.) 


ANTI-CHLORS 


133 


(Na2S203)  and  sodium  bisulphite  (NaHSOs).     The  reactions  in  the  two 
cases  are  as  follows : 

Na2S203+4Cl2+5H20  =  Na2S04+H2S04+8HCl. 

2NaHS03+2Cl2+2H20  =  Na2S04+4HCl+n_'=^04. 


Fig.  106.— VibratoiyTentering  Machine.     (H,  W.  Biitterworth  &  Sons  Co.) 


Fig.  107. — Tentering  and  Drying  Machine. 

After  treatment  with  anti-chlor  the  bleached  cotton  should  be  well  washed 
and  soaped,  for  it  will  be  noticed  from  the  above  reactions  that  acid  is 
formed  in  both  cases. 

10.  Use  of  Acetic  Acid. — In  some  cases  cotton  is  bleached  with  the  use 
of  acetic  rather  than  sulphuric  acid.  Acetic  acid  is  less  liable  to  cause  ten- 
dering of  the  fiber,  and  the  acid  may  be  added  directly  to  the  bath  of 


134 


BLEACHING  OF  COTTON 


chloride  of  lime,  though  this  causes  a  considerable  loss  of  chlorine.  Other- 
wise the  acetic  acid  acts  in  the  same  manner  as  sulphuric  acid.  Although 
this  method  has  been  strongly  advocated  l)y  some  chemists  it  does  not 
seem  to  have  acquired  much  practical  importance. 

11.  Bleaching  with  Sodium  Hypochlorite. — This  reagent  is  also  known 
as  "  chloride  of  soda,"  and  corresponds  to  chloride  of  lime  in  its  bleaching 


Fig.  108. — Upright  Drying  Machine  with  Tension  Stands. 
(Textile-Finishing  Machinery  Co.) 

properties.*     It  may  conveniently  be  prepared  by  adding  a  solution  of 
soda  ash  to  one  of  chloride  of  lime  until  no  further  precipitation  takes  place,  f 

*  Sodi'im  hypochlorite  costs  about  twice  as  much  as  bleaching  powder,  but,  on  the 
other  hand,  its  chlorine  is  twice  as  energetic  in  bleaching.  Therefore  but  little  advan- 
tage in  cost  attends  the  use  of  sodium  hypochlorite,  except  where  a  very  soluble  salt  is 
needed. 

t  A  good  proportion  of  the  ingredients  to  use  is  GO  to  85  lbs.  of  soda  ash  to  100  lbs.  of 
bleaching  powder,  supposing  the  latter  to  be  full  strength  (3G  per  cent  available  chlorine). 


USE  OF  SODIUM  HYPOCHLORITE 


135 


The  white  sediment  of  calcium  carbonate  is  allowed  to  settle  and  the  clear 
liquor  containing  sodium  hj^pochlorite  in  solution  is  drawn  off  and  used 
for  bleaching.   As  there  is  always  a  small  amount  of  caustic  lime  (Ca(0H)2) 


Fig.  109.— Upright  Drying  Machine  with  Folder.     (Textile-Fin  ishing  Machinery  Co.) 

present  in  solutions  of  bleaching  powder,  a  proportionate  amount  of  caustic 
soda  will  be  present  in  this  solution.  *    It  is  generally  used  for  the  bleaching 

*  Sodium  hypochlorite  may  also  l)o  made  by  the  addition  of  caustic  soda  to  a  solu- 
tion of  bleaching  powder;  and  still  another  method  is  the  action  of  sodium  sulphate  on 
bleaching  powder.  The  advantage  of  using  the  latter  is  the  low  price  of  sodium  sul- 
phate; there  is  precipitated  in  this  reaction,  however,  very  finely  divided  calcium  sul- 
phate, which  is  slow  in  settling.  In  order  to  improve  on  this  it  is  best  to  add  some  soda 
ash  along  with  the  sodium  sulphate,  whereby  some  calcium  carbonate  is  formed,  w!u  -h 
settles  rapidly  and  also  carries  down  the  calcium  sulphate. 


136  BLEACHING  OF  COTTON 

of  fine  and  delicate  fabrics  and  where  it  is  not  desirable  to  introduce  any 
lime  into  the  cotton.* 

12.  Bleaching  with  Liquid  Chlorine. — A  bleaching  agent  consist- 
ing of  sodium  hypochlorite  is  prepared  by  saturating  a  cold  solution  of 
caustic  soda  or  soda  ash  with  chlorine  gas.  f     It  is  used  in  the  same  manner 

*  Though  solutions  of  chloride  of  lime  have  now  been  used  in  practical  bleaching 
for  over  a  centur}',  and  the  methods  employed  give  admirable  results  at  a  very  low  cost, 
yet  there  are  certain  disadvantages  and  disagreeable  features  attached  to  the  use  of 
chloride  of  lime,  and  it  would  mark  a  considerable  advance  in  the  art  of  bleaching  if 
these  could  be  overcome.  In  fact,  in  order  to  obviate  some  of  these  disadvantages, 
solutions  of  sodium  hypochlorite  in  some  cases  have  been  employed;  these  solutions 
being  prepared  by  the  interaction  of  soda  ash  with  a  solution  of  chloride  of  lime.  Such 
hypochlorite  liquors,  however,  are  more  or  less  strongly  alkaline,  and  are  rather  expen- 
sive for  practical  use.  It  was  sought,  however,  to  obtain  in  this  manner  a  bleaching 
liquor  that  contained  no  lime  in  solution,  which  would  be  mild  in  its  action  on  the  fiber, 
yet  thorough  in  its  decolorizing  effect  on  the  pigment  matter.  The  chlorine  must  also 
be  in  such  a  form  as  admits  of  its  ready  and  complete  use  as  an  oxidizing  agent,  for 
it  must  be  borne  in  mind  that  the  bleaching  effect  with  chlorine  liquors  is  not  caused 
by  the  direct  action  of  the  chlorine  itself,  but  bj'  its  indirect  action  with  water  to  liber- 
ate oxj'gen  in  a  strongly  reactive  chemical  condition.  In  the  preparation  of  sodium 
hypochlorite  liquors  from  chloride  of  lime,  there  is  more  or  less  loss  in  efficiency  of  the 
original  chlorine  value.  First  there  is  the  original  chemical  reaction  in  the  preparation 
of  the  gaseous  chlorine  (either  by  the  older  chemical  proces.ses  or  by  the  newer 
electrolytic  methods),  then  this  is  converted  into  bleaching  powder  by  reaction  with 
quicklime,  and  this  bleaching  powder  is  finally  by  another  chemical  reaction  brought 
into  the  condition  of  sodium  h\^pochlorite.  Of  course,  in  each  one  of  these  transforma- 
tions there  is  more  or  less  loss  of  value. 

The  use  of  solutions  of  sodium  hj^jochlorite,  however,  was  regarded  with  some  favor, 
especially  for  the  bleaching  of  fine  and  delicate  fabrics,  as  the  chemicals  were  easily  and 
completely  removed  from  the  goods  with  a  minimum  treatment  with  acid  and  washing. 
The  use  of  chloride  of  lime  always  necessitates  a  rather  thorough  acid  treatment  to 
decompose  the  chlorine  compounds  and  allow  of  their  read}'  removal  from  the  fiber. 
A  very  thorough  scries  of  washings  must  al.so  be  given  the  fabric  to  remove  all  trace  of 
the  chemicals  involved.  This  necessitates  the  employment  of  a  large  amount  of  water 
and  a  rather  severe  mechanical  treatment  in  the  washing  machine. 

As  sulphuric  acid  is  mostly  used  for  the  souring  of  bleached  goods,  a  highly  insoluble 
sulphate  of  lime  is  precipitated  in  the  fiber,  and  becomes  rather  difficult  to  remove  from 
the  goods;  while  its  presence,  at  least,  causes  the  bleached  fabric  to  be  harsher,  and  may 
indeed  result  in  other  defects  and  even  tendering.  By  the  use  of  sodium  hypochlorite 
no  insoluble  mineral  compound  is  left  within  the  fiber,  and  as  all  of  the  compounds 
formed  by  the  bleaching  reactions  are  verj-  soluble,  a  comparativeh'  slight  degree  of 
washing  is  required  for  the  complete  removal  of  all  chlorine  derivatives,  the  prolonged 
action  of  which  is  very  injurious  to  the  cotton  fiber. 

t  Chlorine  gas  is  made  on  a  large  scale  as  a  by-product  in  the  manufacture  of  caustic 
soda  by  electrolysis  of  common  salt.  The  gas  is  purified,  dried,  and  liquefied  in  special 
apparatus,  and  put  in  steel  cylinder  containers,  usually  holding  about  100  lbs.  of  the 
liquefied  gas  and  under  a  pressure  of  about  90  lbs.  per  square  inch  at  ordinary'  room 
temperature  (70°  F.).  In  this  form  it  is  very  convenient  to  use  in  the  preparation  of 
hypochlorite  liquors,  as  the  gas  may  be  run  directly  from  the  container  under  proper 
control  in  anj-  desired  amount. 


USE  OF  LIQUID  CHLORINE 


137 


as  sodium  hypochlorite  and  is  a  very  efficient  bleaching  agent.  This 
method  of  bleaching  has  come  into  very  extensive  use  in  the  United 
States  and  has  much  to  recommend  it.  In  the  first  place,  on  dissolving 
chlorine  in  soda  ash  a  clear  liquor  is  obtained  free  from  any  sediment; 
the  long  period  of  settling  is  done  away  with  and  there  is  no  disagreeable 
sludge  to  dispose  of.  In  the  second  place,  the  bleach  liquor  does  not 
contain  any  lime  salts  or  other  compounds  which  are  liable  to  be  pre- 
cipitated in  the  goods  and  give  rise  to  subsequent  defects.  Furthermore 
the  bleach  liquor  prepared  in  this  way  shows  about  twice  the  bleaching 
activity  of  chloride  of  lime  solutions  containing  the  same  amount  of  avail- 
able chlorine.  The  same  thing  is  true  of  sodium  hypochlorite  solutions 
made  from  bleaching  powder  and  soda  ash  or  from  the  electrolysis  of  salt, 
and  is  due  to  the  more  rapid  oxidizing  action  of  the  sodium  salt. 

^ (^ 


Capacity: 
400  ;;alls.  Water 
ICO  !bs.  Chlorine 
350  lbs.  Soda  Ash. 
for  each  charge. 


Ill 

III 

I" 

Pcrtor-iteJ  Pipe     // 


Concrete  T^uLs 


^ 


M 


Fig.  110. — Diagram  of  Liquid  Chlorine  Installation  for  Preparation  of  Sodium 
Hypochlorite  Bleach  Liquor. 


The  usual  method  of  making  a  bleach  liquor  with  liquid  chlorine  is  to 
use  3^  lbs.  of  soda  ash  for  1  lb.  of  chlorine.  It  is  necessary  to  use  this  excess 
of  alkali  in  order  to  prevent  the  decomposition  of  the  solution.  The 
solution  thus  obtained  is  strongly  alkaline,  and  should  be  used  for 
bleaching  soon  after  being  prepared,  as  otherwise  the  bleaching  strength 
will  run  down.  Or,  1|  lbs.  of  caustic  soda  may  be  used  for  1  lb.  of  chlorine. 
This  will  give  a  solution  more  nearly  neutral,  and  it  will  also  keep  longer 
than  the  one  made  with  soda  ash.  The  chlorine,  however,  is  not  absorbed 
as  readily  by  the  caustic  soda  as  it  is  by  the  soda  ash,  and  unless  good 
stirring  is  used,  small  quantities  of  chlorine  gas  will  continually  escape 
while  making  the  solution,  giving  rise  to  very  objectionable  and  corrosive 
fumes.  Also  in  making  the  solution  with  caustic  soda  the  liquor  heats 
up  and  it  is  generally  necessary  to  cool  with  ice  in  order  to  prevent  loss  of 
chlorine.  At  times  the  solution  is  prepared  by  using  a  mixture  of  soda 
ash  and  caustic  soda. 


138 


BLEACHING  OF  COTTON 


In  preparing  a  liquid  chlorine  bleach  liquor  on  a  large  scale  a  cement 
vat  is  used  for  holding  the  alkali  solution.  On  a  basis  of  100  lbs.  of  liquid 
chlorine  use  350  lbs.  of  soda  ash  dissolved  in  400  gallons  of  water.  The 
vat  should  be  about  3|X3|  ft.  and  5  ft.  deep.  The  cylinder  of  Hquid 
chlorine  is  connected  with  a  lead  pipe  running  into  the  vat  and  perforated 
at  the  bottom.  The  flow  of  chlorine  is  regulated  by  the  outlet  valve  on 
the  cylinder,  and  should  be  so  controlled  that  no  gas  escapes  into  the  air. 
As  the  chlorine  evaporates  from  the  liciuid  in  the  cjdinder  there  is  con- 
siderable reduction  of  temperature  which  will  usually  cause  frost  to 
form  on  the  outside  of  the  container,  and  also  cause  a  reduction  in  the 
flow  of  the  gas.     If  it  is  necessary  to  stimulate  the  flow  of  gas  hot  water 


Fig.  111. — Continuou.s  Bleach  System.     (Rigamonti-Togliani.) 


or  steam  maj-  be  run  over  the  container.  Care  should  be  had  not  to 
overcharge  the  solution  with  chlorine,  as  then  the  liquid  will  decompose 
and  soon  entirely  revert  to  salt  with  liberation  of  oxygen  with  efferves- 
cence. The  solution  of  hypochlorite  prepared  from  liquid  chlorine 
may  be  used  in  place  of  the  ordinary  liquor  of  bleaching  powder  without 
further  adjustment  of  the  bleaching  process.  The  proper  strength  of  the 
bleach  Uquor  cannot  be  regulated  by  the  density  or  hydrometer  reading 
(with  either  Twaddell  or  Baume  hydrometer)  as  the  presence  of  a  large 
amount  of  salts  causes  a  rather  high  density  irrespective  of  the  chlo- 
rine strength.  Of  course  in  freshly  prepared  solutions  the  hydrometer 
reading  will  show  the  comparative  strength  of  the  liquor;  for  ordinary 
purpose  of  bleaching  this  should  be  about   1|   to  2|°  Tw.,  but  Hquid 


ELECTROLYTIC  BLEACH  LIQUORS 


139 


chlorine  bleach  solutions  of  this  strength  have  approximately  one-half 
the  active  chlorine  strength  of  chloride  of  lime  solutions  of  the  same 
density,  although  they  possess  the  same  bleaching  ability. 

13.  Electrolytic  Bleach  Liquors. — Solutions  of  sodium  hypochlorite 
prepared  electrolytically  by  the  action  of  the  electric  current  on  a  solution 
of  common  salt  are  also  employed  in  bleaching.  It  is  claimed  that  liquors 
thus  prepared  show  a  much  higher  bleaching  efficiency  than  ordinary 
solutions  of  sodium  hypochlorite,  but  actual  bleaching  tests  carried  out 
with  sodium  hypochlorite  solutions  prepared  from  bleaching  powder  and 
soda  ash,  from  Uquid  chlorine  and  soda  ash,  and  by  the  electrolytic  methods 


Fig.  112. — Electrolyzer   for  Bleach  Liquor.     (National  Laundry  Machine  Co.) 


all  show  practically  the  same  bleaching  effect  for  the  same  content  of  avail- 
able chlorine. 

There  are  a  number  of  different  cells  on  the  market  for  the  preparing  of 
bleaching  liquors  directly,  and  for  small-scale  operations  they  have  proved 
very  successful  in  many  cases,  especially  in  laundries  where  they  are  very 
largely  used.  They  have  also  been  tried  in  various  textile  bleacheries, 
but  here  it  is  mostly  conceded  that  the  use  of  liquid  chlorine  is  more  con- 
venient and  less  costly.  The  current  efficiency  of  cells  making  sodium 
hypochlorite  directly  is  low,  and  on  a  large  scale  it  is  more  economical 
to  make  the  chlorine  and  the  caustic  soda  separately.  One  advantage 
possessed  by  the  electrolytic  bleach  liquor  is  that  it  is  practically  neutral, 


140 


BLEACHING  OF  COTTON 


consisting  essentially  of  a  solution  of  sodium  hypochlorite  with  a  large 
excess  of  common  salt  and  containing  very  little  caustic  soda.  The 
electrolytic  bleach  liciuor  docs  not  keep  for  any  length  of  time,  as  its 
available  chlorine  strength  rapidly  runs  down. 

As  soon  as  the  electric  current  became  a  comparatively  cheap  source 
of  energy,  and  the  possibility  of  chemical  reactions  through  electrolysis 


Fig.  113  —Plant  for  Electrolytic  Bleach.     (National  Laundry  Machine  Co.) 


became  known,  considerable  attention  was  paid  to  the  electrolysis  of  solu- 
tions of  common  salt  (sodium  chloride)  with  a  view  to  the  production  of 
caustic  soda  and  chlorine.  When  a  current  of  electricity  is  passed  through 
a  solution  of  common  salt,  metallic  sodium  is  liberated  at  one  pole  and 
chlorine  gas  at  the  other.  In  a  simple  cell,  however,  secondary  reactions 
immediately  take  place;    the  metalhc  sodium  at  once  reacts  with  the 


ELECTROLYTIC  BLEACH  LIQUORS  141 

water  present,  forming  sodium  hydrate  (caustic  soda)  and  liberating  hydro- 
gen gas.  In  a  short  time  the  caustic  soda  will  reach  the  region  of  the  cell 
containing  the  chlorine,  and  then  another  reaction  occurs  whereby  sodium 
hypochlorite  is  formed.  Hence,  the  products  obtained  by  the  action  of  a 
current  of  electricity  on  a  solution  of  common  salt  are  sodium  hypochlorite 
in  solution  and  hydrogen  evolved  as  a  gas. 

This  process,  however,  cannot  be  carried  out  to  such  an  extent  as  to 
produce  a  concentrated  solution  of  sodium  hypochlorite,  for  secondary 
reactions  soon  take  place,  the  sodium  hypochlorite,  being  decomposed 
into  other  compounds  which  revert  to  sodium  chloride  again.  The  amount 
of  hypochlorite  formed  per  unit  of  current  energy  decreases  with  the 
accumulation  of  the  hypochlorite  in  the  cell,  consequently  in  such  type 
of  cell  it  is  not  feasible  to  produce  anything  but  a  rather  dilute  solution  of 
sodium  hypochlorite.  This  solution,  however,  may  be  employed  directly 
for  bleaching,  being  properly  diluted  to  meet  the  conditions  required. 
The  cell  may  be  made  to  operate  in  a  continuous  or  circulating  manner  by 
the  constant  introduction  of  fresh  salt  solution  in  proportion  to  the  amount 
of  hypochlorite  removed. 

In  order  completely  to  electrolyze  the  salt  it  is  necessary  to  separate 
the  products  resulting  from  the  primary  electrolytic  action.  This  is  accom- 
plished by  the  use  of  a  diaphragm  cell,  so  arranged  that  the  chlorine  is 
removed  as  a  gas  from  one  pole,  and  the  metallic  sodium  by  forming  an 
amalgam  with  mercury  at  the  other  pole.  The  chlorine  is  utilized  by 
absorbing  it  over  quicklime  or  in  milk-of-lime,  for  the  production  of 
bleaching  powder.  The  sodium  is  eventually  obtained  as  caustic  soda  by 
decomposing  the  amalgam  with  water.  The  diaphragm  cell  is  in  extensive 
use  both  in  this  country  and  Europe  for  the  independent  production  of 
bleaching  powder  and  caustic  soda,  and  is  also  operated  in  connection  with 
large  paper  pulp  mills. 

It  is  the  hypochlorite  cell,  however,  which  has  special  interest  to  the 
cotton  bleacher;  for  its  use  as  at  present  developed  does  not  involve  a 
large  outlay  of  capital  and  expert  labor,  and  when  employed  for  the  pro- 
duction of  dilute  solutions  of  sodium  hypochlorite  to  be  used  directly  in 
bleaching,  its  efficiency  can  be  maintained  so  as  to  bring  the  cost  of  the 
bleaching  down  to  a  favorable  comparison  with  chloride  of  lime.* 

*  Outside  of  the  factor  of  cost,  however,  there  are  other  considerations  to  be  borne 
in  mind  when  comparing  the  method  of  electrolytic  bleaching  with  that  in  which  chloride 
of  lime  is  used.  In  the  first  place,  chloride  of  lime  is  an  obnoxious  substance  to  handle. 
This  is  esr  ecially  true  in  mills  where  only  a  moderate  amount  of  bleaching  is  done,  and 
which  consequently  cannot  go  to  the  expense  and  labor  of  handling  the  bleaching  powder 
in  the  most  scientific  manner.  There  is  great  danger  of  "  fly,"  or  dust  from  the  bleach- 
ing powder  when  being  mixed,  contaminating  or  destroying  valuable  products  in  the 
mill.  The  preparation  of  the  bleaching  solution  requires  a  thorough  agitation  of  the 
chemic  with  water,  then  prolonged  settling  and  filtering  in  order  to  obtain   properly 


142  BLEACHING  OF  COTTON 

It  is  a  matter  of  experience  that  when  bleaching  with  chloride  of  lime 
there  is  always  a  strong  odor  of  chlorine  gas  evident,  which  shows  that 

clarified  liquor.  This  requires  a  series  of  tanks  and  pumps  and  the  necessity  of  handling 
large  amounts  of  sludge.  In  order  to  obtain  the  full  value  of  the  chloride  of  lime  it  is 
necessary  to  leach  out  the  powder  several  times.  It  is  therefore  easy  to  understand 
that  the  preparation  of  the  bleach  liquor  in  the  case  of  chloride  of  lirac  must  be  taken 
into  consideration  when  comparing  the  cost  with  that  of  the  electrolytic  liquor. 

In  the  second  place,  the  bleaching  efficiency  of  the  two  solutions  must  be  compared. 
By  this  is  meant,  that  if  we  take  equal  volumes  of  the  two  solutions  both  containing 
the  same  quantity  of  active  chlorine,  will  the  one  solution  bleach  more  fiber  than  the 
other?  A  considerable  amount  of  work,  both  of  a  theoretical  and  practical  nature,  has 
been  done  on  this  question.  The  general  opinion  in  practice  seems  to  be  that  the 
chlorine  in  the  electroWtic  liquor  has  a  higher  bleaching  efficiency  than  that  in  the  liquor 
prepared  from  chloride  of  lime.  Just  why  this  should  be  it  is  difficult  to  say,  but  the 
chemical  and  molecular  condition  of  the  chlorine  in  the  two  cases  may  be  somewhat  dif- 
ferent with  the  result  that  in  the  bleaching  operation  there  is  less  actual  loss  of  chlorine 
when  bleaching  with  elcctrolj'tic  liquors. 

In  the  next  place,  we  must  consider  the  difference  in  the  composition  and  properties 
of  the  solutions  in  the  two  cases.  A  bleaching  liquor  prepared  from  chloride  of  lime  is  a 
complicated  solution,  the  exact  constituents  of  which  have  never  yet  been  satisfactorily 
determined.  It  is  known,  however,  to  contain  a  large  proportion  of  calcium  In-drate 
(caustic  lime)  and  calcium  chloride,  the  active  chlorine  probably  existing  in  combination 
as  calcium  hypochlorite.  The  caustic  lime  makes  the  solution  rather  strongly  alkaline, 
and  unless  care  is  exercised  in  the  treatment  of  fabrics  with  chloride  of  lime  solutions, 
spots  will  be  formed  consisting  of  oxycellulose  resulting  from  the  action  of  the  caustic 
lime  on  the  cotton  fiber.  This  causes  tendering  and  yellowing,  and  is  a  frequent  defect 
in  bleaching. 

The  electrolytic  bleaching  liquor  contains  common  salt  and  sodium  hypochlorite, 
and  is  a  neutral  solution.  The  product  of  decomposition  resulting  from  the  action  of 
the  bleaching  jirocess  is  only  common  salt,  so  that  in  this  solution  there  is  nothing  to  act 
harmfully  on  the  cotton  fiber.  This  is,  however,  supposing  that  the  electrolysis  has  been 
conducted  under  the  proper  conditions,  and  these  involve  three  factors,  namely,  current 
density,  strength  of  brine  solution  and  temperature.  If  these  are  not  in  proper  adjust- 
ment there  is  danger  of  sodium  chlorate  being  formed  in  conjunction  with  the  hypo- 
chlorite, and  this  substance,  if  accumulated  in  sufficient  quantity,  will  act  injuriously 
on  the  fiber. 

The  proper  conditions  of  operating  the  cell,  however,  are  now  rather  thoroughly 
understood,  and  under  proper  supervision  there  is  not  much  danger  of  the  formation  of 
chlorates  in  any  quantity  sufficient  to  cause  injurj'.  We  see,  then,  that  in  electrolytic 
bleach  liquors  jiractically  the  only  ingredient  is  eventually  sodium  chloride  (common 
salt);  or  if  sulphuric  acid  is  employed  in  the  souring  of  the  bleached  goods,  sodium 
sulphate  will  also  be  present.  Both  of  these  sub.stances,  however,  are  neutral,  and  being 
highly  soluble,  are  easily  removed  from  the  fiber  by  a  slight  washing.  With  the  chloride 
of  lime  bleaching,  however,  when  sulphuric  acid  is  emi)loyed  for  souring,  we  have  to 
consider  as  jircscnt  the  nevitral  though  highly  insoluble  calcium  sulphate  and  the  rather 
corrosive  though  highly  soluble  calcium  chloride.  The  caustic  lime  originally  present 
during  bleaching,  of  course,  is  also  converted  into  suli)hate  by  the  souring  process. 
The  calcium  chloride  is  easily  removed  bj'  the  washing  but  more  or  less  of  the  calcium 
sulphate  will  remain  in  the  goods,  and  if  the  souring  is  not  .sufficiently  thorough  there  is 
a  possibility  of  some  caustic  lime  also  remaining,  a  feature  which  is  especially  bad. 


BLEACHING  LOOSE  COTTON  143 

there  must  be  a  considerable  loss  of  this  agent,  for  all  chlorine  which  escapes 
from  the  bleaching  liquors  or  from  the  fabric  when  being  bleached  cannot 
effect  any  bleaching  action  and  is  a  total  loss.  When  using  electrolytic 
bleaching  liquors,  on  the  other  hand,  there  is  no  apparent  odor  of  free 
chlorine  either  in  the  liquors  themselves  or  in  the  fabric  undergoing  bleach- 
ing, hence  it  is  an  indication  of  very  little  loss  of  chlorine  during  the 
bleaching  process.  The  bleaching  action  of  electrolytic  chlorine  is  also 
found  to  be  much  more  rapid  than  that  in  chloride  of  lime  liquors.  This 
also  tends  to  conserve  the  chlorine  from  loss,  and  hence  gives  it  a  higher 
efficiency  in  bleaching. 

Owing  to  the  action  of  the  lime  salts  in  the  bleaching,  and  to  the  fact 
that  more  or  less  of  these  salts  are  left  in  the  finished  bleached  goods, 
the  bleaching  with  chloride  of  lime  will  give  a  somewhat  harsher  feel  to 
the  fabric  than  when  electrolytic  liquors  are  used.  This  seems  at  least 
to  be  the  general  experience  in  practice.  As  a  factor  in  this  connection,  we 
must  also  consider  that  the  latter  form  of  bleaching  does  not  require  as 
severe  an  acid  treatment  nor  as  prolonged  a  washing. 

It  might  be  mentioned  that  there  have  been  other  attempts  at  the 
production  of  electrolytic  bleach  liquors  where  solutions  other  than  com- 
mon salt  have  been  employed.  Several  years  ago  the  Hermite  process 
was  quite  prominent  experimentally  in  England  and  Europe;  and  there 
were  offshoots  from  this  process.  Instead  of  employing  a  solution  of 
common  salt,  solutions  of  sea  water  and  solutions  containing  magnesium 
chloride  were  used.  These  cells,  however,  never  seemed  to  obtain  a  firm 
foothold  in  practice,  and  cells  of  a  later  type  seem  to  have  been  the  most 
successful. 

14.  Bleaching  Loose  Cotton. — Loose  cotton  is  seldom  bleached  for 
purposes  of  spinning,  as  the  bleaching  operation  considerably  deteriorates 
the  spinning  qualities  of  the  fiber.  This  is  due  to  the  fact  that  in  the 
bleaching  the  waxy  matters  are  removed,  and  hence  the  fiber  becomes 
less  plastic  and  coherent,  besides  being  more  brittle.  Sometimes,  how- 
ever, cotton  in  the  half-spun  condition  is  bleached,  and  there  are  mechan- 
ical devices  available  for  the  proper  bleaching  of  cotton  roving  and  slub- 
bing.  A  cold  method  for  bleaching  loose  cotton  has  been  proposed 
wherein  the  cotton  is  first  treated  in  a  suitable  machine  so  that  cold  water 
is  forced  through  the  mass  under  considerable  pressure;  then  a  cold  solu- 
tion of  bleaching  powder  is  circulated  through  the  cotton,  and  subse- 
quently dilute  acid,  followed  by  a  thorough  washing  and  soaping.  This 
method  is  said  to  leave  the  cotton  almost  unimpaired  as  to  its  spinning 
qualities.  Such  a  process  is  attaining  considerable  practical  value  for  the 
spinning  of  filling  cops  from  bleached  stock.  Loose  cotton,  however,  is 
largely  bleached  for  use  as  medicinal  absorbent  cotton.  The  object  in  view 
in  this  case  is  not  only  to  obtain  a  white  and  pure  fiber,  but  also  to  make 


144  BLEACHING  OF  COTTON 

it  highly  absorbent  of  liquids.  In  fact,  the  purpose  is  not  so  much  to 
bleach  the  cotton  in  the  sense  of  destroying  the  color,  as  to  remove  all 
impurities  from  the  fiber  which  may  in  any  manner  interfere  with  its 
ready  absorption  of  liquids.  Hence,  the  chief  ojx^ration  is  a  very  thorough 
boiling-out  to  remove  perfectly  the  waxy  and  resinous  matters.  For  this 
purpose  the  cotton  is  boiled  in  a  comparatively  strong  solution  of  caustic 
soda  under  pressure  for  eight  to  ten  hours.  After  this  treatment  it  is 
bleached  in  the  usual  manner  with  chloride  of  lime  and  sulphuric  acid. 
The  quality  of  absorbent  cotton  is  tested  by  the  readiness  with  which  it 
sinks  in  water. 

15.  Bleaching  Cotton  Skein  Yarn. — In  the  bleaching  of  cotton  yarn  in 
the  form  of  skeins  there  are  several  methods  of  handling.  The  yarn  is 
boiled-out  in  the  customary  manner  in  a  kier,  the  closed  pressure  type 
being  the  one  mostly  used  at  present.  For  conducting  the  chemicking, 
washing,  and  souring,  however,  several  methods  are  available.  In  small 
installations  the  yarn  may  be  placed  on  ordinary  dye  sticks  and  worked 
bj'  hand  in  open  tubs  containing  the  necessary  Hquors.  Or  the  yarn 
may  be  run  in  suitable  machines  where  it  is  rotated  through  the  liquors 
on  a  spider  frame,  being  moved  and  turned  mechanically.  Or  again,  it 
may  be  packed  in  a  wooden  or  concrete  tank  and  the  hquors  are  pumped 
over  the  skeins  and  thus  kept  in  circulation;  this  is  known  as  the  "  still  " 
method  of  bleaching.  For  single  3'arns  of  very  fine  count  (such  as  lOO's, 
120's,  etc.),  which  will  not  stand  much  handling,  apparatus  has  been 
devised  so  that  all  the  operations  of  boiling-out,  chemicking,  washing,  and 
souring  take  place  in  a  single  kier  without  moving  the  goods.  Such  a  kier 
is  lined  with  lead  or  tiles  so  as  to  withstand  the  action  of  the  chemic  and 
the  acid  liquore.  The  kier  is  of  the  closed  or  pressure  type  and  after  the 
skeins  are  carefully  packed  therein  the  air  is  sucked  out  by  a  vacuum 
line,  the  boiling-out  liquor  admitted,  the  steam  is  turned  on  and  the  goods 
are  boiled  for  the  requisite  length  of  time.  Washing  is  then  carried  out, 
after  which  proper  treatment  is  given  wuth  a  chemic  of  sodium  hypo- 
chlorite followed  by  an  anti-chlor  or  acid  and  finally  washing  and  softening. 
The  admission  and  evacuation  of  the  liquors  are  controlled  by  air  suction 
and  pressure,  so  that  the  yarn  is  not  disturbed. 

16.  Bleaching  Cotton  Warps. — This  is  a  method  of  bleaching  which  is 
quite  extensively  practiced  at  the  present  time,  especially  in  cases  where 
the  material  is  to  be  used  in  the  warp  form  for  weaving  and  where  the  yarn 
has  been  mercerized  in  the  warp  and  is  bleached  after  mercerization. 
For  unmercerized  yarn  the  warps  have  first  to  be  boiled-out  as  usual  in 
kiers.  In  handling  the  goods  the  warps  are  usually  doubled  or  linked  up 
in  chains  and  then  run  as  a  long  continuous  string.  After  boiling-out  the 
warps  are  run  through  a  chemic  box  so  as  to  be  padded  with  the  chloride 
of  lime  or  hypochlorite  solution  in  the  same  manner  as  when  bleaching 


BLEACHING  FINE  YARNS 


145 


03 

.a 


a 
13 


146 


BLEACHING  OF  COTTON 


cloth.  The  goods  are  then  folded  down  in  bins  and  allowed  to  bleach  for 
several  hours,  after  which  they  are  run  in  string  form  through  tanks  with 
squeeze  rolls  for  treatment  with  the  wash  waters  and  other  solutions. 
Or  a  still  bleach  may  be  given  by  folding  the  warps  down  in  a  cistern 
and  pumping  the  bleach  and  sour  Uquors  over  the  goods.  These  liquors 
percolate  down  through  the  yam,  are  drawn  off  at  the  bottom  by  the 
pump,  thus  maintaining  the  circulation. 

17.  Bleaching  Knitgoods. — Cotton  knitgoods  (chiefly  used  for  under- 
wear) are  very  largely  bleached  in  the  piece,  or  rather  in  the  roll  of  knitted 

cloth,  previous  to  being  made  up 
into  garments.  The  gray  goods 
as  they  come  from  the  knitting 
machines  must  first  be  well  boiled- 
out  in  a  kier,  and  this  is  especially 
true  of  goods  made  from  carded 
cotton  3'arns  which  contain  a 
considerable  amount  of  motes 
or  seed  particles.  Like  any 
other  form  of  cotton  bleaching 
the  success  of  the  process  depends 
primarily  on  the  proper  and 
complete  boiling-out  of  the  goods. 
In  general  the  method  of  boiling- 
out  knitgoods  is  the  same  as  that 
for  woven  cloth  or  other  forms  of  cotton  material. 

In  regard  to  the  bleaching  operation  proper  (generally  known  as  treat- 
ment with  chemic),  the  method  of  running  knitgoods  is  generalh'  some- 
what different  from  that  of  woven  cloth  owing  to  the  knitted  structure  of 
the  fabric  not  permitting  of  much  tension  on  the  goods.  There  are  two 
general  methods  of  handling  knitgoods.  In  the  first  method  the  goods 
are  run  continuously  in  a  long  chain  through  the  liquor,  entering  the  tank 
at  one  end  and  passing  spirally  up  and  down  over  a  revohdng  winch  or 
wooden  roller  and  passing  out  at  the  other  end  of  the  machine.  In  this 
method  the  cloth  is  simph'  padded  with  the  chemic,  and  as  it  passes  out 
of  the  machine  it  goes  through  a  pair  of  squeeze  rolls  for  the  purpose  of 
removing  the  superfluous  liquor. 

After  coming  from  the  chemic  box  thus  saturated  with  the  liquor, 
the  goods  are  folded  down  in  wooden  boxes  or  crates  and  left  exposed  to 
the  air  and  light  for  several  hours,  or  until  the  bleaching  action  has  pro- 
gressed to  a  satisfactoiy  point.  In  order  to  obtain  a  ver}'  even  bleach  it  is 
well  in  this  process  to  run  the  goods  over  so  as  to  change  the  position  of 
the  materials.  The  cloth  is  then  run  through  an  acid  or  an  anti-chlor 
bath.     On  knitgoods  it  is  probably  better  to  employ  anti-chlor,  as  the 


Fig.  115. — Bleaching  Machine  for  Knitgoods 
in  Roll. 


BLEACHING  KNITGOODS 


147 


chlorine  compounds  are  more  quickly  and  completely  neutralized  and 
there  is  less  danger  of  acid  spots  on  the  goods.  The  treatment  with  either 
anti-chlor  or  acid  is  termed  the  "  souring  "  process,  and  at  this  point  the 
bleaching  action  is  finished.  A  very  thorough  washing  is  then  necessary 
in  order  to  remove  all  trace  of  the  sour  or  acid.  Whichever  agent  is 
employed  for  the  souring,  acid  will  be  formed  in  the  goods  as  a  part  of  the 
reaction,  and  if  this  is  not  completely  removed  the  goods  will  become 
tender  after  a  time  and  turn  yellow.  Subsequent  to  the  washing  process 
it  is  usual  to  give  a  further  treatment  with  a  solution  of  soap  or  other 
softener  in  which  a  little  bluish  violet  coloring  matter  is  dissolved  for  the 
purpose  of  tinting. 

The  second  method  of  handling  the  goods  in  the  bleaching  may  be 
termed  the  discontinuous  method.     Instead  of  running  the  cloth  in  one 


-j»* 


^^■^' 


Fig.  116. — Cylinder  Washer  for  Hosiery  and  Knitgoods. 

long  chain  through  the  machine  continuously,  the  separate  rolls  of  cloth 
are  treated  as  units.  A  string  tub  machine  is  used,  which  consists  of  an 
oblong  tank  over  which  revolves  a  large  spar  roller  or  winch  for  the  purpose 
of  carrying  the  cloth.  The  separate  rolls  of  cloth  are  strung  over  this 
roller  and  then  the  ends  of  each  roll  are  tied  together.  Suitable  prongs 
are  provided  in  the  machine  to  keep  the  different  rolls  apart.  In  this 
system  the  goods  are  bleached  together  in  the  machine,  and  do  not  require 
to  be  aged  in  the  air  while  saturated  with  the  chemic  as  in  the  other  process. 
All  of  the  processes  are  carried  out  in  the  same  machine  without  removal 
of  the  goods.  The  first  bath  to  be  given  is  the  chemic,  which  consists  of 
a  solution  of  hypochlorite  of  about  1  to  1|°  Tw.,  and  the  cloth  is  run 
in  this  solution  for  one-half  to  one  hour,  depending  on  the  degree  of 
bleaching  desired.     If  the  cloth  is  made  from  low-grade  carded  yarns 


148  BLEACHING  OF  COTTON 

which  are  very  much  specked  with  seed  motes,  it  will  be  necessary  to  heat 
the  bleaching  liquor  to  100°  F.  towards  the'  end  of  the  run  in  order  to 
remove  the  seed  particles. 

After  the  treatment  with  the  chemic  solution,  the  latter  is  run  out  of 
the  machine,  and  the  goods  are  then  given  a  good  washing  with  fresh 
running  water  for  thirty  minutes  to  one  hour,  depending  on  the  amount  of 
water  emploj^ed.  The  treatment  with  anti-chlor  solution  is  next  given, 
using  about  5  per  cent  of  anti-chlor  on  the  weight  of  the  goods.  The 
souring  will  require  about  twenty  minutes.  A  thorough  Avashing  is  again 
given,  after  which  the  goods  may  be  soaped  and  tinted  if  desired. 

The  latter  method  of  treatment  is  to  be  preferred  to  the  former  or 
continuous  process  for  several  reasons.  In  the  first  place,  in  the  con- 
tinuous process  one  end  of  the  cloth  receives  a  longer  treatment  with  the 
chemic  than  the  other  end.  The  first  end  of  the  cloth  out  of  the  chemic 
bath  remains  at  the  bottom  of  the  boxes  and  consequently  is  the  last  end 
out  of  the  boxes  to  go  into  the  W'ashing  and  souring  baths.  The  differ- 
ence in  time  between  the  passage  of  the  two  ends  will  vary  from  one-half 
to  one  hour,  depending  on  the  length  of  the  chain  of  goods.  This  intro- 
duces a  serious  element  of  unevenness  in  the  bleaching  W'hich  is  con- 
tinually causing  trouble  in  this  sj^stem  of  handling.  In  the  second  sj-stem 
each  portion  of  the  goods  receives  the  same  treatment  all  through,  so  this 
factor  of  unevenness  is  eliminated.  In  the  second  place,  the  continuous 
system  requires  the  use  of  stronger  solutions  of  chemic,  which  is  always 
an  element  of  danger  in  the  production  of  streaked  goods  and  over-bleached 
spots  leading  to  tender  and  spotted  fabrics.  Furthermore  the  fact  that 
the  goods  remain  for  such  a  considerable  period  saturated  with  this  strong 
chemic  may  lead  to  streaked  and  tender  goods.  The  lime  and  chlorine 
compounds  are  also  more  difficult  to  remove  from  the  cloth,  and  there  is 
also  danger  of  portions  of  the  goods  drying  out  at  the  edges  and  thus  lead- 
ing to  the  formation  of  tender  parts. 

As  to  the  size  of  the  machine  required  for  the  treatment,  it  would  be 
best  to  obtain  a  kier  of  sufficient  size  to  take  care  of  a  day's  production. 
The  tanks  required  in  the  continuous  process  should  be  of  sufficient  size 
to  hold  about  500  gallons  of  w^ater.  The  tank  required  for  the  discon- 
tinuous method  should  hold  about  1000  gallons,  and  should  be  of  sufficient 
length  to  be  able  to  run  twelve  to  fourteen  rolls  of  cloth,  as  this  would 
probably  take  care  of  about  500  lbs.  of  goods  at  a  time. 

In  addition  to  the  boiling  kier  and  the  tanks  a  hydro-extractor  will  be 
required  for  removing  the  excess  of  Avater  from  the  goods.  A  drjdng 
apparatus  will  also  be  necessary,  of  which  there  are  two  forms  in  general 
use.  In  the  one  the  rolls  of  damp  cloth  are  drawn  up  over  a  wire  cylinder 
through  which  hot  air  is  blown.  When  the  cloth  arrives  at  the  upper  end 
it  is  dry  and  is  rolled  up  into  an  even  roll  in  a  sHghtly  stretched  condition 


BLEACHING  KNITGOODS 


149' 


SO  as  to  remove  all  creases  and  folds.     In  the  other  system  of  drying  the 
cloth  is  carried  through  a  drying  chamber  heated  with  steam  coils  and 


Fig.  117. — Roll  Machine  for  Bleaching  Knitgoods. 


Fig.  118. — Dryer  for  Knitgoods. 


through  which  air  is  passed  by  means  of  a  fan.  The  goods  are  folded 
up  and  down  over  rods  in  the  loose  state,  and  on  this  account  it  is  neces- 
sary to  smooth  out  the  wrinkles  in  the  cloth  afterwards  by  a  special  device 


150  BLEACHING  OF  COTTON 

of  stretching  and  taking  up  on  a  roller.  In  the  case  of  formed  goods  in 
which  the  cloth  is  of  uneven  width  throughout  its  length,  the  second  system 
of  drying  is  probably  the  most  desirable. 

18.  Experimental. — Exp.  33.  Bleaching  Cotton  by  Means  of  Tinting.— Take  a 
skein  of  cotton  yarn  which  lias  been  boiled  out  in  soap  and  soluble  oil,  and  tint  it  by 
working  in  a  bath  containing  300  cc.  of  water  and  a  few  drops  of  Methyl  Violet  5B, 
cold  for  twenty  minutes.  Then  wash  and  dry.  The  small  amount  of  bluish  violet 
coloring  matter  neutralizes  the  slight  tint  of  brownish  yellow  natm-al  to  the  cotton, 
with  the  result  that  a  neutral  gray  tint  is  produced;  and  this  latter  color  is  less  per- 
ceptible to  the  eye  than  either  the  yellow  or  violet  color,  consequently  the  tinted  cotton 
appears  to  be  whiter  than  the  natural  fiber.  Care  must  be  taken  not  to  give  the  cotton 
too  pronounced  a  violet  color;  it  will  be  found  that  a  very  little  dyestutf  will  suffice. 

Exp.  34.  Bleaching  Cotton  with  Chloride  of  Lime. — Take  a  weighed  skein  of  cotton 
yarn  and  boil  it  out  in  (-austic  soda  as  described  in  E.\p  .  23.  Take  another  weighed  skein 
and  boil  it  out  with  soap  as  described  in  Exp.  25;  also  a  third  weighed  skein  scoured  with 
Monopol  oil  as  in  Exp.  26.  Wash  these  skeins  well  and  steep  in  a  solution  of  chloride 
of  lime  (bleaching  powder)  of  2°  Tw.  strength.  Work  for  several  minutes  until  the 
fiber  is  thoroughly  saturated  with  the  liquor;  then  immerse  in  the  solution  and  allow 
to  stand  for  one  hour.  Then  squeeze  and  rinse  in  water,  and  "  sour  "  by  passing  for 
fifteen  minutes  through  a  cold  bath  of  sulphm-ie  acid  of  1°  Tw.  strength.  Finalh"  wash 
well  in  water  to  remove  all  trace  of  acid.  Reweigh  each  skein  and  calculate  the  per- 
centage of  loss  in  each  case,  and  compare  the  bleach  obtained  with  each  method  of  boil- 
ing-out. Test  the  skeins  for  acid  by  moistening  a  portion  with  a  little  water  and  pressing 
agakist  it  a  piece  of  blue  litmus  paper;  if  the  test  paper  turns  red,  acid  is  still  present  in 
the  fiber,  and  the  washing  has  been  imperfect,  with  a  result  that  the  cotton  will  soon 
become  tender.  To  test  the  bleached  cotton  for  traces  of  chlorine  which  may  remain 
after  bleaching,  take  a  portion  of  the  skein  and  warm  with  a  small  amount  of  potassiimi 
iodide-starch  solution;  if  a  blue  color  is  developed,  there  is  still  chlorine  in  the  fiber. 
The  test  solution  may  be  prepared  by  dissolving  a  little  starch  paste  (made  by  boiling 
up  some  starch  with  water  to  a  paste)  in  a  solution  of  potassium  iodide. 

Exp.  35.  Use  of  "  Anti-chlor  "  for  Removing  Chlorine  in  Bleaching. — Take  a  skein 
of  cotton  yarn  which  has  been  boiled-out  in  caustic  soda  in  the  usual  manner,  and 
bleach  it  for  one  hour  in  a  cold  solution  of  chloride  of  lime  at  2°  Tw.,  then  wash  in  water 
On  a  portion  of  the  skein  place  a  drop  or  two  of  the  potassium  iodide-starch  solution, 
and  it  will  be  found  that  a  blue  color  is  developed,  showing  the  presence  of  chlorine 
Now  pass  the  skein  through  a  bath  containing  a  little  sulphuric  acid  for  a  few  minutes 
and  wash  again.  Test  with  the  potassivmi  iodide-starch  solution  again,  and  it  will  still 
be  found  that  free  chlorine  is  present.  Prepare  a  bath  containing  300  cc.  of  water  and 
1  gram  of  sodium  thiosul])hate  (sodium  hyposulphite)  and  pass  the  skein  through  this 
solution  cold  for  ten  minutes.  Wash,  and  again  test  with  the  potassium  iodide-starch 
solution,  when  it  will  be  found  that  the  free  chlorine  has  been  neutralized.  The  sodium 
hyposulphite  is  called  "  anti-chlor  "  when  used  for  this  purpose;  sodium  bisulphite  will 
also  answer  the  same  purjiose. 

Exp.  36.  Bleaching  Loose  Cotton  for  Absorbent  Purposes. — Weigh  out  10  grams  of 
loose  cotton  and  boil  for  one  hour  in  a  bath  containing  300  cc.  of  water  and  5  grams  of 
caustic  soda.  Rinse  off  well  in  fresh  water  and  bleach  in  a  cold  solution  of  chloride  of 
lime  at  2°  Tw.  for  one  hour.  Rinse,  and  pass  through  a  cold  solution  of  sulphuric  acid 
at  1°  Tw.  for  twenty  minutes.  Then  wash  well  in  several  changes  of  water  until  all 
acid  is  removed.  Then  squeeze  and  dry.  Reweigh  the  sample  and  calculate  the  per- 
centage of  loss.     Test  the  bleached  cotton  for  absorbent  qualities  by  placing  a  small  bit 


EXPERIMENTAL  STUDIES 


151 


of  it  on  the  surface  of  cold  water;  if  it  is  perfectly  absorbent,  it  should  sink  at  once. 
Try  a  small  piece  of  raw  cotton  in  the  same  manner,  and  it  will  be  found  that  the  latter 
does  not  sink  at  all. 

Exp.  37.  Tinting  and  Softening  of  Bleached  Cotton. — Boil-out  four  skeins  of  cotton 
yarn  in  caustic  soda  in  the  usual  manner;  wash  well  in  water,  and  bleach  for  one  hour  in 
a  cold  bath  of  chloride  of  lime  at  2°  Tw.  Wash,  squeeze,  and  pass  for  fifteen  minutes 
through  a  cold  bath  of  sulphuric  acid  at  1°  Tw.  Wash  in  two  changes  of  water.  Then 
test  the  skeins  with  litmus  paper,  and  the  chances  are  that  they  will  still  show  the  pres- 
ence of  acid.  Set  one  of  the  skeins  aside  for  comparison.  Take  another  one  of  the 
skeins  and  work  for  fifteen  minutes  in  a  bath  containing  300  cc.  of  water,  1  gram  of  soap, 
and  ^^(j  per  cent  of  Methyl  Violet  5  B;  have  the  temperature  at  about  140°  F.  Then 
squeeze  and  dry.  Take  a  third  skein  and  treat  in  the  same  soap  bath,  but  add  j^-^ 
per  cent  of  the  coloring  matter;   squeeze  and  dry.     Take  the  fourth  skein  and  treat  in 


Fig.  119— Raw  Stock  Bleaching  Machine.     (Delahunty  Dyeing  Machine  Co.) 


the  same  manner  with  the  soap  solution,  but  add  J^  per  cent  of  the  dyestuff ;  squeeze 
and  dry.  The  percentages  of  the  dyestuff  are  to  be  calculated  on  the  weight  of  the 
cotton  tinted.  That  is,  ^i,  per  cent  on  10  grams  of  cotton  would  be  0.0005  gram.  The 
solutions  provided  should  contain  0.1  gram  of  dyestuff  per  liter  (1000  cc);  hence  1  cc. 
would  represent  0.0001  gram  of  dyestuff,  and  it  would  require  5  cc.  to  give  the  necessary 
lOT  P<^r  c^"t'  or  10  cc.  for  j^g  per  cent,  or  20  cc.  for  ^\  per  cent.  After  the  several  skeins 
have  dried,  compare  the  feel  or  softness  of  the  first  with  that  of  the  others  which  have 
been  treated  with  the  soap  bath.  Also  compare  the  degrees  of  tinting  of  the  latter 
three  skeins  and  the  difference  in  the  character  of  the  white  obtained  in  each  case. 

Exp.  38.  Use  of  Acetic  Acid  in  Bleaching. — Boil  out  a  skein  of  cotton  yarn  with 
caustic  soda  in  the  usual  manner  and  bleach  for  one  hour  in  a  cold  solution  of  chloride 
of  hme  at  2°  Tw.  containing  also  a  little  acetic  acid.  Then  wash  well  in  fresh  water  and 
pass  through  the  dilute  soap  bath  as  described  above.  It  will  be  noticed  that  some 
chlorine  is  given  off  in  the  bleach  bath  containing  the  acetic  acid,  but  the  bleaching  does 


152  BLEACHING  OF  COTTON 

not  roquiro  the  after  upo  of  an  acid,  from  which  there  is  always  danger  of  tendering  the 
fiber. 

Exp.  39.  Use  of  Lime  Boil  in  Bleaching  Cotton. — ^repare  a  sohition  of  hme-water 
bj-  slaking  10  grams  of  (juicklime  (oxide  of  calcium,  CaO)  with  a  small  quantity  of  water, 
and  then  diluting  to  300  cc.  Boil  a  weighed  skein  of  cotton  yarn  in  this  bath  for  one 
hour,  then  wash  and  pass  through  a  cold  bath  containing  300  cc.  of  water  and  3  cc.  of 
concentrated  hydrochloric  acid;  work  for  fifteen  minutes.  Wash  and  bleach  for  one 
hour  in  a  cold  solution  of  chloride  of  lime  at  2°  Tw.  Wash,  and  pass  back  through  the 
cold  acid  bath  for  fifteen  minutes.  Then  wash  well  and  soap  as  usual  in  a  dilute  warm 
soap  bath.  Wash  and  dry.  Reweigh  and  calculate  the  percentage  of  loss.  Compare 
this  method  of  bleaching  with  the  previous  ones.  The  first  treatment  with  acid  is 
required  in  order  to  dissolve  out  any  lime  compounds  formed  in  the  fiber,  which  would 
otherwise  remain  and  tender  the  cotton,  and  also  not  allow  the  chloride  of  lime  to  act  as 
penecth'  as  it  should. 

Exp.  40.  Use  of  Sodium  Hypochlorite. — Prepare  a  bath  containing  sodium  hypo- 
chlorite .solution  of  1  ~  Tw,  In  this  cold  bath  steep  for  one  hour  a  skein  of  cotton  yarn 
previously  boiled-out  with  caustic  soda.  Wash  and  pa.?s  through  a  cold  bath  of  sul- 
phuric acid  at  1°  Tw.  for  fifteen  minutes.  Then  wash  well  and  soap  as  usual.  Sodium 
hypochlorite  is  prepared  by  adding  a  solution  of  soda  ash  to  one  of  chloride  of  lime, 
allowing  the  precipitate  of  calcium  carbonate  to  settle  and  drawing  off  the  clear  liquor. 
It  is  more  efficient  as  a  bleaching  agent  than  chloride  of  lime,  and  is  also  less  liable  to 
cause  tendering  of  the  fiber.     It  is  more  expensive,  however,  than  chloride  of  lime. 

Exp.  41.  Comparison  of  the  Use  of  Sulphuric  and  Hydrochloric  Acids  in  Bleaching 
Cotton. — Take  two  skeins  of  cotton  j'arn  which  have  been  boiled-out  with  caustic  soda 
and  bleach  them  in  the  usual  manner  with  chloride  of  lime  solution  at  2°  Tw.  Without 
washing,  take  one  of  the  skeins  and  pa.ss  through  a  bath  containing  300  cc.  of  water  and 
3  cc.  of  h\'drochloric  acid  cold  for  fifteen  minutes,  then  wash  well  and  dry.  Take  the 
other  skein  and  treat  in  a  similar  manner  with  a  solution  of  2  cc.  of  sulphuric  acid  in  300 
cc.  of  water;  wash  well  and  dry.  Notice  that  in  the  bath  containing  the  hydrochloric 
acid  there  is  no  precipitate  formed,  as  the  lime  compound  with  this  acid  is  soluble  in 
water;  whereas  in  the  sulphuric  acid  bath  a  precipitate  of  calcium  sulphate  is  formed 
which  will  remain  to  a  greater  or  lesser  extent  in  the  cotton. 

Exp.  42.  Use  of  Sodium  Peroxide  for  Bleaching  Cotton. — -Prepare  a  bath  containing 
400  cc.  of  water  and  3  cc.  of  concentrated  sulphuric  acid;  have  this  solution  cold  and 
then  carefully  add  with  constant  stirring  4  grams  of  sodium  peroxide.*     After  all  of  the 

*  Sodium  perborate  has  also  been  brought  forward  as  a  bleaching  agent,  more  espe- 
cially for  use  in  laundries.  It  is  a  substance  somewhat  similar  in  its  bleaching  effect  to 
sodium  peroxide.  It  is  more  expensive,  however,  than  sodium  peroxide,  and  further- 
more, only  contains  10.4  per  cent  of  active  oxygen  as  compared  with  about  20  per  cent 
in  sodium  peroxide.  Sodium  perborate,  however,  is  more  stable  than  the  peroxide,  and 
it  was  principallj'  on  this  account  that  it  attracted  attention  for  purposes  of  bleaching. 
Sodium  peroxide  decomposes  with  violent  rapidity  when  dis.solved  in  cold  water;  whereas 
sodium  perborate  requires  to  be  dissolved  in  hot  water,  and  the  resulting  products  are 
hydrogen  peroxide,  caustic  soda,  and  borax.  On  this  account,  the  bleaching  bath  can 
be  employed  at  an  elevated  temperature.  Sodium  perborate  has  been  particularly  put 
forward  as  a  bleaching  agent  for  laundries,  and  a  number  of  proprietary  mixtures  have 
been  put  on  the  market  which  combine  scouring  and  bleaching  properties.  Pcrsil  is  a 
mixture  of  soap,  soda  a.sh,  sodium  silicate  and  a  small  amount  of  sodium  perborate. 
Clarax  is  a  mixture  of  borax,  sodium  phosphate  and  sodium  perborate;  Ozonilc  is  a  mix- 
ture similar  to  Pcrsil  containing  the  ingredients  in  a  somewhat  different  proportion. 
Perborin  is  pure  sodium  perborate,  wliile  Perborin  M  is  a  mixture  of  Perborin  with  soap 
and  alkali. 


EXPERIMENTAL  STUDIES  153 

latter  has  been  added  test  the  solution  with  a  strip  of  bkic  Htmus  paper.  If  the  bath  is 
acid  in  reaction,  the  paper  will  turn  red,  but  if  not  add  a  few  more  drops  of  acid  until 
the  bath  does  show  a  slightly  acid  reaction.  This  insures  the  fact  that  all  of  the  caustic 
alkali  produced  by  the  solution  of  the  sodium  peroxide  in  water,  has  been  neutralized. 
Then  add  a  few  drops  of  sodium  phosphate  solution  until  the  test  paper  shows  that  the 
bath  is  slightly  alkaline  in  reaction.  This  is  done  because  the  bath  bleaches  more 
efficiently  when  somewhat  alkaline.  Heat  the  bath  to  120°  F.,  and  work  in  it  a  skein  of 
cotton  yarn  which  has  been  boiled-off  in  caustic  soda.  After  working  for  about  ten 
minutes  so  as  to  thoroughly  impregnate  the  fiber  with  the  liquid,  immerse  the  skein 
beneath  the  solution  and  allow  it  to  stay  for  twenty-four  hours.  Then  remove  the  skein, 
wash  well  in  fresh  water,  and  finally  soap  in  a  dilute  bath  containing  a  little  Methyl 
Violet  for  tinting  in  the  usual  manner.  Compare  this  bleach  with  that  obtained  by  the 
use  of  chloride  of  lime. 

Exp.  43.  Showing  the  Influence  of  Iron  in  the  Bleaching  Bath  v/ith  Sodium  Perox- 
ide.— Prepare  a  bleaching  bath  as  above  described  with  sulphuric  acid  and  sodium 
peroxide,  but  add  to  it  a  small  quantity  of  iron  (such  as  a  small  tack,  etc.).  Carry  out 
the  bleaching  of  a  skein  of  cotton  yarn  in  exactly  the  same  manner  as  before,  and  after 
finishing  all  of  the  operations,  notice  the  effect  of  the  presence  of  the  iron  on  the  character 
of  the  bleach. 

Exp.  44.  Bleaching  Cotton  with  Potassium  Permanganate. — Prepare  a  bath  con- 
taining 400  cc.  of  water  and  2  cc.  of  concentrated  sulphuric  acid.  Work  a  skein  of  cot- 
ton yarn  which  has  been  boiled-out  with  caustic  soda  in  the  usual  manner  in  this  bath 
cold  for  ten  minutes;  then  add  5  cc.  of  potassium  permanganate  solution  (containing 
50  grams  per  liter)  and  work  cold  for  twenty  minutes  longer.  Then  wash  in  fre.sh  water, 
when  it  will  be  noticed  that  the  cotton  has  become  brown  in  color,  due  to  the  hydrate 
of  manganese  which  has  been  precipitated  in  the  fiber.  Now  pass  the  skein  through  a 
bath  containing  400  cc.  of  water  and  5  cc.  of  sodium  bisulphite  solution  (containing  50 
grams  per  liter) ;  work  cold  for  twenty  minutes,  or  until  the  cotton  is  white.  The  sodium 
bisulphite  reduces  and  dissolves  the  manganese  hydrate  from  the  cotton  and  leaves  the 
bleached  fiber.  Finally  wash  well  and  dry.  Compare  the  quality  of  this  bleach  with 
the  other  methods, 


CHAPTER   V 

CLASSIFICATION  OF  DYES 

1.  General  Classification  of  Dyestuffs. — With  respect  to  their  general 
properties  nearly  all  coloring  matters  may  be  divided  into  six  general 
classes,  as  follows: 

(a)  Acid  Dyes.  (d)   Mordant  Dyes. 

(b)  Basic  Dyes.  (e)    Sulphur  Dyes. 

(c)  Substantive  Dyes.  (/)    Vat  Dyes. 

This  classification  in  a  general  way  is  based  on  the  chemical  nature  of  the 
dyestuff  and  its  reaction  towards  the  fiber.  The  following  is  a  brief  sum- 
mary of  these  properties : 

(a)  Acid  Dyes.  Salts  of  color-acids;  dye  animal  fibers  directly;  do  not  dye  vege- 
table fibers;   mostly  applied  to  vi^ool  and  silk.* 

(h)  Basic  Dyes.  Salts  of  color-bases;  dye  animal  fibers  directly;  dye  vegetable 
fibers  on  a  tannin  mordant;  mostly  applied  to  cotton  and  silk. 

(c)  Siibslantive  Dyes.  Of  neutral  chemical  nature;  dye  both  animal  and  vegetable 
fibers  directly;  mostly  applied  to  cotton  and  somewhat  to  both  wool  and  silk. 

(d)  Mordant  Dyes.  Of  neutral  chemical  nature;  dye  neither  animal  nor  vegetable 
fibers  directly,  but  require  a  metallic  mordant;   mostly  applied  to  wool. 

(e)  Stdphur  Dyes:  Soluble  in  sodium  sulphide;  used  exclusively  for  vegetable 
fibers,  which  they  dye  directly. 

(/)  Vat  Dyes.  Soluble  in  sodium  hydrosulphite;  dye  both  animal  and  vegetable 
fibers  directly;  used  mostly  on  cotton  i^nd  to  some  extent  on  wool;  characterized  by 
great  fastness. 

The  great  majority  of  the  dyestuffs  used  at  the  present  time  are  derived 
from  coal-tar  products,  the  vegetable  dyes,  with  few  exceptions,  Ijeing 
almost  obsolete. 

*  According  to  Knccht,  the  distinction  of  the  acid  dyes  as  a  separate  group  is  based 
on  practical  requirements  rather  than  on  strictly  scientific  principles.  On  the  one  hand 
there  is  no  sharp  line  of  demarcation  between  them  and  the  direct  cotton  colors,  and  on 
the  other  hand,  the  acid  colors,  acid  chrome  colors,  and  mordant  colors  are  frequently 
related  to  each  other,  a  numlicr  of  dyes  belonging  pra(!tically  to  two  of  these  groups 
or  even  to  all  of  them,  as  is,  for  instance,  the  case  with  Cotton  Yellow  G.  A  few  like 
the  Soluble  Blues,  can  also  be  dyed  like  the  basic  colors.  The  common  characteristic 
of  the  acid  dyes  is  that  they  are  dyed  on  wool  and  silk  in  an  acid  bath  and  that  they 
can  be  mixed  with  each  other  to  produce  compound  shades. 

154 


GENERAL  GROUPING  OF  DYES  155 

(a)  Acid  Dyes.     Mostly  derived  from  azo  compounds  of  benzene  and  toluene. 

(b)  Basic  Dyes.     Mostly  derived  from  aniline  and  its  homologues. 

(c)  Suhslantive  Dyes.     Mostly  derived  from  benzidine  and  tolidine. 
{d)  Mordant  Dyes.     Mostly  derived  from  anthracene. 

(e)  Sulphur  Dyes.  Derived  from  various  organic  products  by  fusion  with  sulphur 
and  sodium  suljihide. 

(/)  Vat  Dyes.  Derived  principally  from  anthracene  and  carbazol,  including  also 
some  derivatives  of  indigo. 

Previous  to  the  discovery  of  the  coal-tar  dyes,  the  coloring  matters 
employed  were  of  either  vegetable  or  mineral  origin. 

(n)  Vegetable  Dyes.  Logwood,  Indigo,  Fustic,  Hypernic,  Cochineal,  Madder,  Cutch, 
Camwood,  Brazil-wood,  Archil,  Quercitron,  Safflower,  Persian  Berries,  etc. 

(6)  Mineral  Dyes.  Iron  Black,  Iron  Buff,  Manganese  Bistre,  Chrome  Yellow,  Prus- 
sian Blue,  etc. 

The  first  coal-tar  dyestuff  was  discovered  in  1856  by  Perkin;  it  was 
known  as  Mauve,  and  was  soon  followed  by  other  aniline  dyes.  It  is 
wrong,  however,  to  apply  the  term  "  aniline  "  colors  to  all  coal-tar  dyes,  as 
there  are  now  many  which  are  not  derived  from  aniline. 

For  the  same  amount  of  actual  coloring  matter  the  coal-tar  dyes  are 
in  general  much  cheaper  than  the  vegetable  colors;  they  have  also  far 
greater  intensity  of  color,  are  much  brighter,  and  in  many  cases  are  faster. 

Based  on  their  general  methods  of  application,  we  may  classify  prac- 
tically all  of  the  dyes  used  at  the  present  time  into  the  following  groups: 

(a)  Acid  dyes,  such  as  Acid  Violet,  Naphthol  Yellow,  etc. 

(b)  Basic  dyes,  such  as  Magenta,  Methylene  Blue,  etc. 

(c)  Mordant  dyes,  such  as  Alizarine  Red,  Gallocyanine,  etc.,  and  most  of  the  vegetable 
dyes. 

(d)  After-chromed  dyes,  such  as  Chromotrope,  Diamond  Black,  etc. 

(e)  Substantive  dyes,  such  as  Benzopurpurine,  Chrysophenine,  etc. 
(/)   Developed  dyes,  such  as  Diamine  Black  BH,  Primuline,  etc. 
(gf)    Naphthol  dyes,  such  as  Paranitraniline  Red,  etc. 

(h)  Coupled  dyes,  such  as  Benzo  Nitrol  Brown,  etc. 

(i)   Sulphtir  dyes,  such  as  Sulphur  Black,  Sulphur  Blue,  etc. 

(j)    Vat  dyes,  such  as  Indigo,  Indanthrene  Blue,  etc. 

(/c)  Oxidized  dyes,  such  as  Aniline  Black. 

(I)    Mineral  pigment  dyes,  such  as  Chrome  Yellow,  Prussian  Blue,  etc. 

The  most  important  of  these  classes,  and  those  containing  the  greatest 
number  and  the  most  diversified  colors,  are  the  six  groups  mentioned  in 
the  first  paragraph  of  this  section.* 

*  There  is  also  a  group  of  dyes  known  as  spirit  colors,  which  are  insoluble  in  water 
and  require  to  be  dissolved  in  wood  alcohol,  acetin,  etc.  They  are  used  to  some  extent 
in  the  dyeing  of  silk  and  as  pFinting  colors,  but  their  principal  use  is  for  the  coloring  of 
varnishes,  etc. 


156 


CLASSIFICATION  OF  DYES 


The  acid  dyes  arc  principally  used  for  the  dyeing  of  wool  and  silk,  and 
only  to  a  limited  extent  for  the  dyeing  of  cotton  or  other  vegetable  fibers.* 
They  arc  applied  to  the  animal  fibers  in  baths  containing  either  sulphuric 
acid  or  acetic  acid. 

The  basic  dyes  are  used  chiefly  for  the  dyeing  of  cotton  and  silk ;  only  a 
few  members  of  this  group  are  used  in  wool-dyeing.  They  are  applied 
to  the  animal  fibers  directly  from  neutral  baths,  f     For  cotton,  or  other 


Fig.  120. — Kettle.s  for  Dissolving  Dyes,  Extracts,  and  Finishing  Materials. 


vegetable  fibers,  a  mordant  of  an  acid  character  (such  as  tannic  acid)  is 
required. 

*  The  acid  dyes  are  of  considerable  importance  for  the  d3'eing  of  jute,  as  this  fiber 
differs  noticeably  from  most  of  the  other  vegetable  fibers  in  its  chemical  composition. 
Instead  of  consisting  of  more  or  less  pure  cellulose,  it  is  composed  of  an  alteration 
product  of  cellulose  known  as  ligno-cellulose,  and  the  latter  possesses  the  property  of 
combining  directly  with  the  acid  dyes.  Jute  also  combines  directly  with  the  basic 
dyes  without  the  intervention  of  a  tannin  mordant,  as  is  required  by  cotton. 

t  A  separate  group  of  dj-estuffs  is  frequently  made  of  the  eosin  or  phlhalein  dyes. 
This  group  includes  certain  of  both  the  acid  and  basic  dj'es,  which  are  what  might  be 
termed  "  neutral  "  dyes.  They  comprise  the  eosins,  erythrosins,  phloxines,  rose  ben- 
gals, and  rhodamines.  They  are  applied  in  neutral  or  slightly  acid  baths,  and  are 
largely  used  for  the  dyeing  of  silk,  though  to  a  certain  extent  also  for  wool  and  cotton. 
All  these  dyes  are  pink  in  color  and  are  characterized  by  great  brilliance  and  fluores- 
cence. The  rhodamines  in  reality  belong  to  the  basic  group,  whereas  the  others  are 
acid  dyes. 


GENERAL  PROPERTIES  OF  DYES  157 

The  mordant  dyes  arc  almost  exclusively  used  for  the  dyeing  of  wool, 
wi^h  the  exception  of  Alizarine  Red,  which  is  also  largely  used  for  the 
dyeing  of  cotton  (for  Turkey  Rod).  These  dyes  do  not  have  a  direct 
affinity  for  any  of  the  fibers,  and  require  the  use  of  a  metallic  mordant 
(usually  potassium  bichromate)  in  their  application. 

The  after-chromed  dyes  are  very  similar  to  the  mordant  dyes  in  their 
general  characteristics,  but  the  mordant  is  applied  after  the  dyeing. 
These  colors  are  used  exclusively  on  wool  and  have  a  direct  affinity  for  this 
fiber,  though  the  color  so  obtained,  as  a  rule,  has  little  value.  The  after- 
chroming  process  usually  alters  this  color  considerably  and  gives  it  fast- 
ness. 

The  substantive  dyes  are  so  called  because  they  have  a  direct  affinity  for 
all  fibers.  They  are  primarily  cotton  dyes,  though  they  are  also  used  to 
some  extent  on  wool  and  silk.     They  are  applied  in  neutral  baths. 

The  developed  dyes  are  used  almost  exclusively  on  cotton,  though  a  few 
are  also  applicable  to  silk.  They  are  first  dyed  in  a  manner  similar  to  the 
substantive  colors  in  a  neutral  solution;  the  dyed  material  is  then  treated 
with  a  solution  of  nitrous  acid  (obtained  by  the  addition  of  acid  to  a  solu- 
tion of  sodium  nitrite) — a  process  known  as  diazotizing, — and  afterwards 
with  a  solution  of  beta-naphthol  (or  other  similar  body),  which  is  known 
as  the  developer,  and  from  which  this  class  of  dyes  receives  its  name. 
By  these  operations  a  new  dyestuff  is  built  up  in  the  fiber. 

The  naphthol  dyes  are  somewhat  similar  in  general  to  the  preceding 
group,  only  the  order  of  the  operations  is  reversed.  The  material  to  be 
dyed  is  first  treated  with  a  solution  of  beta-naphthol  (or  other  similar 
developer),  and  then  with  a  solution  of  a  diazotized  base  representing  the 
dyestuff.  In  this  manner  a  dyestuff  is  actually  made  in  the  fiber.  These 
dyes  are  but  few  in  number  and  are  applied  only  to  cotton. 

The  coupled  dyes  are  another  similar  group,  the  material  being  first 
dyed  with  a  substantive  color  and  then  treated  with  a  solution  of  diazo- 
tized paranitraniline ;  this  resulting  in  the  formation  of  a  new  dyestuff 
in  the  fiber.  Such  dyes  are  apphcable  only  to  cotton  and  are  quite  limited 
in  number  and  range  of  color. 

The  sulphur  dyes  are  also  applied  almost  exclusively  to  cotton,  though 
in  certain  cases  they  may  also  be  used  on  silk.  They  are  dyed  with  the 
aid  of  sodium  sulphide  which  is  added  to  the  dyebath,  and  the  dyestuff 
apparently  contains  sulphur  compounds  in  its  composition.  In  other 
respects  they  are  very  similar  to  the  substantive  dyes. 

The  vat  dyes  form  a  small  group  of  colors  employed  on  all  the  fibers. 
The  dyestuffs  themselves  are  insoluble  and  require  to  be  first  reduced  by 
means  of  a  strong  reducing  agent  (such  as  sodium  hydrosulphite  or  other 
suitable  substance)  and  dissolved  in  an  alkaline  liquor.  This  combina- 
tion forms  the  so-called  "  vat."     Indigo  is  the  chief  representative  of  this 


158 


CLASSIFICATION  OF  DYES 


group,  though  other  dyes  of  a  shnilar  character  have  lately  been  added, 
such  as  the  indanthrene,  heUndone,  and  algol  colors,  as  well  as  the  thio- 
indigo  colors. 

The  group  of  oxidized  dyes  is  practically  limited  to  only  one  member 
known  as  Aniline  Black.  This  dye,  which  is  extensively  used,  is  formed 
by  the  proper  oxidation  of  aniline  directly  in  the  fiber.  It  is  used  prin- 
cipally on  cotton  and  to  a  lesser  extent  on  silk. 

The  mineral  pigment  dyes  are  colored  compounds  of  the  metals  formed 
by  the  precipitation  in  the  fiber  of  suitable  metallic  salts,  such  as  Chrome 
Yellow  formed  by  precipitation  of  lead  acetate  in  the  fiber  with  potassium 
bichromate.     These  dyes  are  almost  entirely  used  for  dyeing  cotton;  some 


Fig.  121. — Modern  Type  of  Kettle  for  Preparing  Solutions  for  Dyeinj 


were  formerly  used  for  dyeing  wool  and  silk,  but  this  application  of  them 
is  now  almost  entirely  discontinued. 

2.  Action  of  Dyestufifs  on  the  Textile  Fibers. — The  various  classes  of 
dyestuffs,  as  already  indicated  above,  react  quite  differently  with  the  sev- 
eral textile  fibers.  Though  there  is  considerable  similarity  in  their  reac- 
tion with  wool  and  silk,  as  constituting  the  general  class  of  animal  fibers, 
still  even  here  there  are  points  of  difference  to  be  observed  in  the  dyeing 
properties  of  these  two  fibers.  The  greatest  differences,  however,  are  to 
be  noticed  between  the  animal  fibers  on  the  one  hand  and  cotton  (and 
the  vegetable  fibers  in  general)  on  the  other  hand.  The  methods  of  dyeing 
and  the  particular  dyestuffs  employed  which  are  suitable  for  one  fiber  may 
be  totally  inappropriate  for  the  other  fiber;    therefore  in  an  intelhgcnt 


REACTIONS  BETWEEN  DYES  AND  FIBERS  159 

understanding  of  the  process  of  dyeing,  it  is  necessary  both  to  be  able  prop- 
erly to  classify  the  dyestuff  and  also  to  be  well  acquainted  with  the  dif- 
ference in  the  behavior  of  these  groups  of  dyes  on  the  various  fibers  or 
materials  to  be  dyed. 

Although  there  is  no  doubt  a  certain  degree  of  chemical  reactivity  to 
be  considered  as  existing  between  the  fiber  and  the  dyestuff  in  the  dyeing 
process,  as  far  as  the  practical  dyeing  is  concerned  we  have  chiefly  to  con- 
sider the  physical  distribution  of  the  coloring  matter  through  the  sub- 
stance of  the  fiber.  In  a  true  dyeing  operation  the  color  is  not  simply 
deposited  on  the  surface  of  the  fiber,  but  saturates  or  penetrates  it  through- 
out. If  a  cross-section  of  a  dyed  fiber  is  examined  microscopically,  it  will 
be  found  that  the  color  extends  through  the  interior,  and  with  but  few 
exceptions  (what  might  be  called  'pigment  dyes)  there  is  no  apparent  sepa- 
ration of  dyestuff  particles  from  the  general  substance  of  the  fiber.  This 
saturation  of  the  color  through  the  fiber  is  generally  somewhat  gradual, 
and  for  complete  penetration  usually  requires  a  rather  prolonged  boiling 
or  steeping  in  the  dyebath.  Just  what  causes  the  combination  of  the  dye- 
stuff  with  the  fiber,  and  in  what  form  this  combination  exists,  is  not  def- 
initely known,  though  a  discussion  of  these  points  will  be  considered 
under  the  theory  of  dyeing. 

3.  Action  of  Dyestuffs  on  Wool. — Wool  is  to  be  considered  as  the  most 
reactive  of  all  the  fibers  towards  dyestuffs.*  Practically  all  the  different 
classes  of  dyestuffs  will  combine  with  wool;  although  in  certain  cases  it 
may  not  be  practical  to  use  on  this  fiber  the  methods  of  dyeing  required 
for  some  of  the  groups  of  dyes.  Sulphur  dyes,  for  example,  are  not  appli- 
cable to  wool  because  the  process  of  dyeing  requires  the  use  of  a  strongly 
caustic  alkaline  bath  (sodium  sulphide)  which  would  destroy  the  wool. 
Also  with  some  other  groups,  such  as  the  developed,  the  naphthol  and  the 
coupled  dyes,  either  dyebaths  injurious  to  the  wool  are  employed,  or  the 

*  Wool  has  a  greater  affinity  for  dyestuffs  than  has  any  other  textile  material. 
Being  an  animal  fiber  it  combines  directly  with  acid,  basic,  and  substantive  colors. 
The  active  constituent  in  wool  which  is  supposed  to  take  part  in  the  dyeing  process  is 
"  keratine,"  and  this  is  apparently  a  very  reactive  chemical  body.  The  wool  fiber  is  a 
colloidal  substance,  and  no  doubt  forms  with  most  coloring  matters  a  "  solid  solution." 
Its  chemical  composition,  however,  apparently  plays  an  important  role  in  the  applica- 
tion of  certain  classes  of  dyestuffs,  such  as  the  acid  and  basic  dyes.  The  affinity  of 
wool  for  most  dyes  is  much  greater  at  a  boiling  temperature  than  in  the  cold;  hence  the 
dyeing  of  wool  nearly  always  takes  place  in  a  solution  at  or  near  the  boiling  point.  This 
condition,  however,  will  depend  somewhat  on  the  character  of  the  dyestuff  employed; 
the  phthalein  dyes,  for  instance  (including  the  eosins  and  rhodamines)  are  usually  applied 
at  a  temperature  of  about  140  to  150°  F.,  and  many  acid  dyes  at  a  temperature  of  180 
to  190°  F.;  whereas  the  most  of  the  mordant  dye?  require  the  bath  to  be  at  the  boiling 
temperature  for  their  proper  fixation. 

Many  of  the  basic  dyes,  on  the  other  hand,  will  combine  rather  easily  with  wool 
even  in  cold  baths. 


160  CLASSIFICATION  OF  DYES 

color  may  be  produced  in  a  much  more  satisfactory  manner  with  other 
dyes  more  readily  applicable  to  this  fiber. 

Owing  to  the  close  similarity  in  the  chemical  natures  of  wool  and  silk, 
these  two  fibers  exhibit  much  the  same  properties  in  their  affinities  towards 
dyestuffs.  One  of  the  chief  differences,  however,  between  the  two  fibers 
in  this  respect  is  in  the  proper  temperature  of  dyeing.  In  the  case  of 
silk  the  dyestuff  appears  to  combine  more  readily  with  the  fiber  at  lower 
temperatures  (about  140  to  160°  F.)  while  with  wool  the  dyeing  takes 
place  better  at  higher  temperatures  (200  to  212°  F.,  or  practically  at 
the  boil).  In  practice,  wool  is  usually  dyed  in  a  boiling  bath,  although 
actual  boihng  is  not  absolutely  necessary  except  in  certain  cases  of  very 
thick  goods  or  hard  coarse  wools.* 

The  general  relation  of  wool  to  the  various  groups  of  dyestuffs  is  as 
follows : 

The  basic  dyes  are  applied  to  wool  directly  in  a  hot  water  solution 
without  necessarily  any  further  addition  to  the  bath;  good  examples  of 
such  dyes  are  Magenta  (Fuchsine),  Methyl  Violet,  and  Auramine.  All  of 
the  basic  dyes,  however,  do  not  react  in  precisely  the  same  manner  with 
wool,  this  being  somewhat  dependent  on  the  chemical  nature  of  the  par- 
ticular dye  in  question.  Some  of  the  basic  azo  dyes,  for  example,  show  a 
greater  affinity  for  wool  when  alum  is  present  m  the  dyebath,  as  is  illus- 
trated by  the  case  of  Bismarck  Brown.  Some  of  the  diphenylnaphthyl 
basic  dyes,  like  Victoria  Blue,  exhibit  better  dyeing  properties  towards 
wool  when  acid  is  added  to  the  dyebath. 

The  group  of  acid  dyes  is  to  be  considered,  par  excellence,  the  one 
most  suitable  for  wool  dyeing.  Most  of  the  acid  dyes  show  more  or  less 
affinity  for  wool  even  in  a  neutral  glaubersalt  bath,  and  certain  members 
of  this  group  may  be  practically  dyed  in  that  manner.  Generally  speak- 
ing, however,  the  full  affinity  of  the  acid  dyes  for  wool  is  only  developed  by 
the  proper  addition  of  acid  to  the  bath.  Sulphuric  or  acetic  acid  is  usually 
employed  for  this  purpose.  The  application  of  the  acid  dyes  to  wool  is  a 
very  simple  process  and  usually  proceeds  without  any  special  difficulties, 
which  accounts  for  the  great  popularity  of  these  colors  for  the  dyeing  of 
all  manner  of  woolen  materials. 

Among  the  substantive  dyes  a  number  give  very  good  colors  on  wool, 
showing  quite  a  strong  affinity  for  the  fiber  in  a  neutral  bath,  though 
usually  the  dyeing  takes  place  better  in  a  bath  slightly  acidulated  with 

*  Some  dyers  consider  that  it  is  necessary  to  boil  the  wool  hard  in  order  to  dye  it 
perfectly.  With  but  few  exceptions,  however,  this  does  not  appear  to  be  generally 
necessary.  Most  dyes  belonging  to  the  acid,  basic,  and  substantive  classes  require  a 
temperature  only  up  to  about  195°  F.,  and  even  some  of  the  mordant  dyes  may  be  satis- 
factorily dyed  at  this  temperature.  It  may  also  be  remarked  in  this  connection  that 
fine  woolen  and  worsted  yarns  of  such  a  character  as  to  be  easily  felted  and  tangled, 
should  never  be  vigorously  boiled  in  the  dyeing. 


REACTIONS  BETWEEN  DYES  AND  FIBERS 


161 


acetic  acid.  Others  show  but  httle  or  no  affinity  for  wool,  and  are  con- 
sequently not  applicable  to  this  fiber;  they  belong  mostly  to  the  azoxy 
dyes,  such  as  Mikado  Yellow.     A  relatively  small  group  of  the  substan- 


FiQ.  122.— Autoclave  (Pressure  Kettle)  for  Preparing  Dyewood  Solutions. 

tive  dyes  known  as  the  sulphon  colors,  is  especially  adapted  to  the  dyeing 
of  wool,  being  applied  in  a  neutral  or  slightly  acid  bath.  There  is  usually 
a  considerable  difference  in  the  affinity  of  the  substantive  dyes  for  wool 
and  cotton  in  the  temperature  of  dyeing.     As  a  rule,  wool  takes  up  the 


162  CLASSIFICATION  OF  DYES 

dyostuff  better  at  a  tomporature  at  or  near  the  boil,  while  the  color  feeds 
on  the  cotton  better  at  a  lower  temperature. 

The  true  mordant  dyes  (alizaiines)  have  but  little  affinity  for  unmor- 
danted  wool.  Some  of  the  sulphonated  soluble  alizarines  will  exhibit 
a  certain  degree  of  dyeing  properties,  though  the  colors  are  generally 
useless  with  respect  to  fastness.  Towards  suitabl}^  mordanted  wool 
(prepared  with  metallic  bases  such  as  those  of  chromium,  aluminium,  iron, 
copper,  tin,  etc.),  however,  the  mordant  dyes  exhibit  a  strong  attraction, 
so  strong  in  fact,  at  high  temperatures  that  uneven  shades  will  generally 
be  the  result  unless  the  dyeing  process  is  started  at  a  comparatively  low 
temperature  (100  to  140°  F.).  The  reaction,  in  this  case,  however, 
is  more  between  the  dyestuff  and  the  metallic  mordant  than  between 
the  dyestuff  and  the  fiber  itself.  The  mordant  dyes  are  largely  used  on 
wool  for  the  production  of  fast  colors.  Most  of  the  vegetable  dyes  are 
mordant  colors,  and  the  entire  group  forms  the  so-called  adjective  dyes  of 
the  old  classification. 

The  behavior  of  the  after-chromed  dyes  towards  wool  is  some- 
what analogous  to  that  of  the  mordant  dyes  in  that  a  suitably  fast  color- 
lake  is  only  formed  after  a  mordanting  operation.  On  the  other  hand, 
however,  the  after-chromed  dyes  are  more  analogous  to  the  acid  dyes  in 
that  they  combine  directly  with  wool  from  an  acid  bath,  though  the 
color  obtained  in  this  manner  may  have  unsatisfactory  fastness.  This 
class  of  dyes  has  become  a  very  favorite  one  for  use  on  wool  for  the  pro- 
duction of  fast  colors,  as  usually  the  dyeing  operation  is  simpler  and 
cheaper  than  with  the  true  mordant  dyes.  Some  of  the  after-chromed 
dyes  are  chemically  analogous  to  the  alizarines,  being  derivatives  of  anthra- 
cene, and  it  is  probably  that  with  these  the  after-chroming  is  a  true  mor- 
danting operation  and  the  dyestuff  combines  with  the  metallic  base  to 
form  a  color-lake.  Other  of  the  after-chromed  dyes,  however,  are  azo 
dyes  and  they  are  chemically  very  different  from  the  true  mordant  dyes. 
It  is  probable  that  in  such  cases  (as  with  Chromotrope,  Diamond  Black, 
Alizarine  Yellow  G,  etc.),  the  chroming  acts  as  an  oxidizing  reaction, 
though  apparently  the  metallic  mordant  base  also  takes  part  in  the  fixa- 
tion of  the  color. 

The  vat  dyes,  of  which  Indigo  is  a  good  representative,  are  insoluble 
in  water  and  requii-e  an  alkaline  reduction  to  form  a  dyebath  or  "  vat." 
Indigo  is  extensively  used  for  dyeing  wool  and  some  of  the  other  vat 
dyes  are  also  applied  to  wool  to  a  limited  extent,  though  they  are  not  used 
to  the  same  degree  as  on  cotton.  It  cannot  be  said  that  there  is  a  direct 
affinity  of  the  dyestuff  for  the  wool,  for  as  a  matter  of  fact  the  fiber  is  only 
impregnated  with  the  solution  of  the  reduced  dyestuff  (leuco  compound) 
by  capillary  attraction,  and  the  coloring  matter  is  subsequently  precip- 
itated within  the  fiber  in  an  insoluble  condition  by  oxidation  in  the  air. 


REACTIONS  OF  DYES  WITH  SILK 


163 


Owing  to  the  highly  insoluble  character  and  the  stable  nature  of  these 
precipitated  dyestuffs,  the  colors  so  produced  as  a  rule  are  exceedingly  fast. 

4.  Action  of  Dyestuffs  on  Silk. — Silk  is  only  second  to  wool  in  its  gen- 
eral reactivity  towards  dyestuffs,  and  owing  to  its  similar  chemical  nature 
(being  a  proteoid  of  an  amino-acid  character  like  wool)  it  resembles  wool 
in  exhibiting  both  acid  and  basic  qualities.  In  the  dyeing  of  boiled-off 
silk  some  difference  is  to  be  observed  from  that  of  soupled  silk.  The 
latter  is  still  coated  with  a  considerable  layer  of  sericin  or  silk-gum,  and 
when  dyed  most  of  the  color  is  to  be  found  in  the  sericin  layer. 

With  the  basic  dyes  silk  combines  very  readily,  and  these  colors  may 
be  applied  in  a  neutral  bath;  usually,  however,  boiled-off  liquor  is  added 
as  this  causes  a  more  uniform  absorption  of  the  color.     The  basic  dyes, 


Fig.  123. — Raw  Stock  Dyeing  Machine.     (Klauder-Weldon  Dyeing  Machine  Co.) 


as  a  rule,  feed  on  the  silk  better  at  a  temperature  of  about  160  to  180°  F., 
for  when  boiled  or  subjected  to  too  prolonged  a  heating  some  of  the  color 
will  be  stripped  from  the  fiber.  Also  at  high  temperatures  the  color  is 
liable  to  be  uneven  as  well  as  superficially  deposited.  Frequently  acetic 
acid  is  added  to  the  bath  in  dyeing  basic  colors,  as  this  promotes  evenness 
and  penetration.  The  basic  dyes  are  extensively  used  on  silk  goods  on 
account  of  their  intense  and  brilliant  colors. 

The  acid  dyes  also  show  a  strong  affinity  for  silk,  many  of  them  dyeing 
this  fiber  even  from  a  neutral  solution,  though  better  results  are  usually 
obtained  by  employing  a  bath  acidified  with  either  sulphuric  or  acetic  acid.* 
Most  of  the  acid  dyes  may  be  apphed  to  silk  at  temperatures  considerably 

*  The  combination  of  the  acid  colors  with  silk  is  not  as  strong  as  with  wool;  appar- 
ently the  basic  properties  of  the  silk  fiber  are  too  weak  to  furnish  a  stable  combination 
with  the  color-acid.  On  this  account  few  of  the  acid  dyes  can  be  fixed  on  silk  fast  to 
wasliing. 


164 


CLASSIFICATION  OF  DYES 


below  the  boil ;  in  fact  if  too  high  a  temperature  is  used  uneven  colors  will 
result.  As  with  the  basic  dyes,  it  is  customary  to  make  an  addition  of 
boiled-off  liquor  to  the  bath  in  order  to  even  up  the  colors. 

Silk  may  also  be  dyed  satisfactorily  with  many  of  the  substantive  dyes, 
though  most  of  these  do  not  react  as  well  with  silk  as  they  do  with  wool 
and  cotton,  and  in  some  cases  the  color  is  not  taken  up  at  all.  The  dyeing 
may  be  carried  out  in  a  neutral  bath,  though  better  results  are  usually 
obtained  if  some  acetic  acid  is  added.  A  moderate  temperature  of  about 
160  to  180°  F.  is  used. 


Fig.  124. — Sectional  View  through  the  Klauder-Weldon  Raw  Stock 
Dyeing  Machine. 


The  mordant  dyes  have  but  slight  affinity  for  the  plain  silk  fiber,  but 
when  previously  prepared  with  a  metallic  mordant  the  silk  will  become 
dyed.  The  mordant  dyes,  however,  are  rarely  used  on  silk,  with  the 
single  exception  of  Logwood,  which  is  extensively  used  for  dyeing  black. 
As  with  the  case  of  wool,  the  dyeing  of  silk  with  the  mordant  dyes  is  rather 
a  combination  of  the  dycstuff  with  the  mordant  than  with  the  fiber. 

The  vat  dyes  may  also  be  applied  to  silk  using  a  vat  similar  to  that 
employed  for  wool.  These  dyes  possess  more  of  the  property  of  pigments 
precipitated  within  the  fiber,  and  there  is  no  real  combination  of  the 
dyestuff  with  the  silk.  The  other  classes  of  dyestuffs  are  rarely,  if  ever, 
used  on  silk. 

5.  Action  of  Dyestuffs  on  Cotton. — Unlike  the  animal  fibers  cotton  is 
quite  inert  towards  most  dyestuffs  with  the  exception  of  the  substantive  or 


ACTION  OF  DYES  ON  COTTON  165 

direct  cotton  colors.  As  the  substance  of  the  cotton  fiber  is  cellulose  and 
not  a  proteoid,  this  material  is  chemically  very  inactive  so  that  it  com- 
bines with  neither  the  basic  nor  the  acid  dyes.  The  same  is  also  true  with 
respect  to  its  affinity  for  metallic  salts  or  mordants. 

With  the  basic  dyes  cotton  shows  no  affinity  and  can  only  be  dyed 
with  these  colors  by  first  preparing  the  fiber  with  a  tannin  mordant.* 
Bleached  cotton  shows  a  slightly  greater  attraction  for  basic  dyes  than 
raw  cotton,  and  this  becomes  considerably  increased  if  the  cotton  has 
been  over-oxidized  in  the  bleaching.  Mercerized  cotton  is  also  somewhat 
more  reactive  with  basic  colors  than  ordinary  cotton. 

The  acid  dyes  are  also  not  reactive  with  cotton,  but  when  applied  to 
the  fiber  in  connection  with  an  alum  mordant  may  be  used  for  a  loose  form 
of  coloring  which  possesses  but  slight  stability  towards  washing,  f  By 
impregnating  the  cotton  with  a  solution  of  albumin  (so-called  "  animal- 
ized  "  cotton)  the  fiber  may  be  dyed  rather  satisfactorily  with  many  acid 
dyes;  in  this  case,  however,  it  is  really  the  albumin  which  is  dyed  rather 
than  the  cotton  itself. 

Towards  the  substantive  dyes  cotton  has  a  strong  affinity  which  permits 
of  the  ready  dyeing  of  this  fiber  with  these  colors.  It  is  doubtful,  however, 
if  this  reaction  is  due  to  any  chemical  activity  between  the  fiber  and  the 
dyestuff,  but  is  rather  a  colloidal  combination  of  the  two.  The  sub- 
stantive dye,  however,  is  apparently  not  fixed  in  an  insoluble  condition  in 
the  fiber,  as  steeping  in  water  will  nearly  always  continuously  remove 
some  of  the  color.  The  developed,  naphthol,  and  coupled  dyes  all  prac- 
tically belong  to  the  general  class  of  substantive  dyes,  the  only  difference 
being  that  they  are  built  up  directly  in  the  fiber.  As  they  are  mostly 
insoluble  substances  the  colors  they  furnish  are  much  faster  as  a  rule 
than  the  other  substantive  dyes. 

The  sulphur  dyes  are  also  substantive  in  character  in  that  they  com- 
bine directly  with  the  cotton.  They  are  chemically  different,  however, 
from  the  other  direct  cotton  colors;  and  being  insoluble  in  water,  also 
yield  much  faster  dyeings. 

Towards  the  mordant  and  after-chromed  dyes  cotton  is  very  inert,  and 
owing  to  the  fact  that  the  fiber  is  also  quite  inactive  with  solutions  of 
metallic  salts  there  is  considerable  difficulty  in  applying  a  mordant,  so 
with  the  single  exception  of  Turkey  Red  (dyed  with  Alizarine)  these  dyes 
are  practically  never  employed  on  cotton. 

The  vat  dyes  apparently  react  with  cotton  merely  by  a  saturation  of 

*  Exception  must  apparently  be  made  in  the  case  of  Victoria  Blue  B,  which  dyes 
unmordanted  cotton  a  full  shade  from  a  bath  containing  acetic  acid. 

t  Even  the  color-lake  of  the  acid  dye  with  the  alum  in  this  case,  seems  to  be  decom- 
posed by  water  and  the  color  removed.     The  Soluble  Blues  are  faster  to  washing. 


166  CLASSIFICATION  OF  DYES 

the  fiber  with  the  sokition  of  the  reduced  dj'e,  and  a  subsequent  precip- 
itation of  the  pigment  therein.  Owing  to  the  extremely  insoluble  char- 
acter of  these  dyes  the  colors  they  produce  are  very  fast,  and  on  this 
account  they  have  an  extensive  use  in  cotton  dj'eing. 

In  the  case  of  the  natural  dyes  these  all  belong  to  the  mordant  class 
with  respect  to  cotton,  with  the  exception  of  Curcuma  and  Safflower, 
which  may  be  dyed  directly  on  cotton  in  a  manner  similar  to  the  sub- 
stantive dyes.  With  Aniline  Black  and  the  mineral  dyes  their  relation  to 
cotton  may  be  considered  simply  as  the  precipitation  of  an  insoluble  pig- 
ment within  the  fiber. 

6.  The  Use  of  Mordants. — It  has  been  seen  that  certain  dyes  (such 
as  the  alizarine  and  anthracene  series)  do  not  form  stable  coml^inations 
with  the  fibers.  If  wool,  for  example,  is  boiled  in  a  solution  of  Alizarine 
Red,  in  a  certain  sense  it  will  become  dj^ed,  but  the  color  may  easily  be 
washed  from  the  filier.  In  other  words,  though  the  dyestuff  is  soluble  in 
the  fiber,  the  color-lake  does  not  become  "  fixed."  These  dyes,  however, 
form  very  permanent  color-lakes  with  many  metallic  oxides,  such  as  those 
of  aluminium,  chromium,  iron,  etc.*  Furthermore,  wool  (and  silk  also) 
has  the  property  of  dissolving  and  fixing  these  metallic  salts  much  in  the 
same  manner,  for  instance,  as  basic  dyes  are  taken  up  by  the  fiber.  There- 
fore if  the  animal  fibers  are  first  boiled  in  a  solution  of  such  metallic  salt  a 
certain  quantity  of  the  metallic  oxide  becomes  dissolved  and  fixed  in  the 
substance  of  the  wool  (or  silk) ,  and  the  fiber  so  prepared  can  then  be  dyed 
a  permanent  color  with  the  alizarine  (or  other  mordant)  dj^estuffs.  Cot- 
ton (and  the  vegetable  fibers  in  general)  does  not  have  the  property  of 
dissolving  and  fixing  these  metallic  salts  (or  mordants)  to  any  extent; 
hence  this  method  of  mordanting  and  dyeing  is  not  readily  applicable  to 
the  vegetable  fibers.  The  vegetable  fibers  do,  however,  possess  the 
property  of  combining  with  tannic  acid,  and  this  furnishes  a  method  of 
so  preparing  these  fibers  that  they  may  be  dyed  with  the  basic  dj^estuffs. 
The  salts  of  those  metals  which  are  more  or  less  easily  dissociated  in  boiling 
water  are  most  applicable  as  mordants  for  the  animal  fibers.  These  salts 
include  compounds  of  chromium,  aluminium,  iron,  tin,  copper,  etc.,  the 
most  important  mordants  for  wool  being  potassium  and  sodium  bichromates 
(chrome)  and  alum  (or  aluminium  sulphate).  Pyrolignite  of  iron  (crude 
ferrous  acetate)  and  the  so-called  nitrate  of  iron  (really  a  ferric  sulphate) 

*  Mil  Her- Jacobs  (Jour.  Soc.  Dyers  &  Col.,  1885  and  1886)  considers  that  the  r61e  of 
mordants  is  not  only  to  combine  with  the  dyestuff  to  form  an  insoluble  precipitate,  but 
also  to  reduce  the  permeability  of  the  fiber,  so  as  to  obtain  an  osmotic  effect  by  mem- 
branous diffusion.  To  substantiate  this  view  he  states  that  Alizarine  Red  requires 
fifteen  times  the  amount  of  aluminium  hydrate  for  the  proper  development  of  the  color 
as  would  be  necessary  to  form  normal  aluminium  alizarate. 


ACTION   OF   MORDANTS  167 

are  used  largely  for  silk;  although  their  use  in  this  connection  is  primarily 
for  purposes  of  weighting,  their  mordanting  action  being  a  secondary  con- 
sideration. The  color-lake  in  the  case  of  a  mordant  dye  consists  of  the 
triple  compound:  fiber — metallic  oxide — dyestuff.  The  mordant  dyes 
are  of  a  mild  acid  character  or  contain  groups  which  permit  of  them 
uniting  chemically  with  the  basic  metallic  oxide.*  On  account  of  the 
fact  that  cotton  cannot  be  readily  mordanted  after  the  manner  of  wool 
the  general  class  of  mordant  dyes  finds  little  or  no  application  to  this  fiber. 
About  the  only  instance  of  their  use  in  this  connection  is  the  dyeing  of 
Turkey  Red,  and  this  requires  a  special  and  complicated  process.  One 
feature  to  be  noticed  in  connection  with  the  mordant  dyes  is  that  the  same 
dyestuff  often  gives  very  different  colors  on  different  mordants;  Alizarine 
Red,  for  instance,  when  dyed  on  a  chrome  mordant  gives  a  rather  dull 
purplish  red;  on  an  aluminium  mordant  it  gives  a  bright  red;  on  a  tin 
mordant  it  gives  a  scarlet;  and  on  an  iron  mprdant  it  gives  a  dull 
purple. 

The  term  ''  mordant  "  is  derived  from  the  old  French  word  "  mordre," 
meaning  to  bite  or  corrode,  it  being  the  idea  among  the  early  dyers  that 
the  action  of  the  mordant  was  to  corrode  the  fiber  somewhat  so  as  to  open 
up  the  pores  and  allow  of  the  better  penetration  of  the  coloring  matter. 
It  was  not  known  till  a  later  period  that  the  mordant  actually  combined 
with  the  dyestuff  to  form  a  color-lake,  f     In  the  popular  mind  the  idea 

*  J.  Thorn  has  yrointed  out  that  mordants  exhibit  an  elective  affinity  for  dyestuffs; 
that  is  to  say,  they  possess  a  greater  attraction  for  some  dyes  than  for  others.  For 
example,  cloth  mordanted  with  alumina  is  dyed  yellow  with  Quercitron;  if  the  same 
sample  is  boiled  in  a  decoction  of  Logwood  the  latter  will  displace  the  Quercitron  and  the 
color  changes  from  yellow  to  purple;  while  if  the  sample  is  further  boiled  with_Madder, 
the  Logwood  in  turn  is  displaced  and  the  color  changes  to  red.  On  the  other  hand, 
Knecht  {Jour.  Soc.  Dyers  &  Col.,  1904,  p.  98)  has  shown  that  metallic  mordants  them- 
selves may  displace  each  other,  as  when  cloth  mordanted  with  tannate  of  iron  (slate 
color)  is  boiled  with  a  solution  of  titanium  chloride,  the  iron  is  displaced  with  the  for- 
mation of  tannate  of  titanium  (orange  color) . 

t  The  use  of  mordants  was  really  more  extensive  in  the  early  days  of  dyeing  than  it 
is  now,  owing  to  the  fact  that  most  of  the  dyestuffs  (the  vegetable  dyes)  then  available 
required  a  mordant  for  their  proper  fixation  in  the  fiber.  In  many  cases  very  complicated 
methods  of  mordanting  were  employed,  whereby  mixed  mordants  consisting  of  the  salts 
of  several  metals  were  employed  in  order  to  produce  certain  effects.  This  is  apparent 
if  one  refers  to  the  old  books  on  dyeing  giving  recipes  used  previous  to  the  advent  of  the 
coal-tar  colors.  The  instruction  is  often  found  "  to  wash  in  the  river  "  after  dyeing. 
It  is  supposed  that  the  beneficial  effect  to  be  obtained  by  this  injunction  was  due  to  the 
metallic  salts  present  in  the  river  water.  The  use  of  hard  water  containing  lime  and 
magnesium  salts  was  recommended  in  dyeing  Turkey  Red  so  that  a  compound  alum-lime 
(or  alum-magnesia)  mordant  could  be  obtained.  Prudhomme  has  shown  (Bull,  de  Mul- 
Jwuse,  1891,  page  39  and  217)  that  alumina  precipitated  in  the  presence  of  magnesia  is 
insoluble  in  caustic  alkahes.     Nickel  and  cobalt  salts  also  aot  in  the  same  manner;  while 


168  CLASSIFICATION  OF  DYES 

of  mordants  is  not  very  clearly  defined;  many  are  apt  to  include  under 
this  term  almost  any  chemical  which  is  used  in  connection  with  the  dye- 
stuff  in  its  application  to  the  fiber;  for  instance,  the  common  salt,  glauber- 
salt,  or  acid  that  may  be  used  to  aid  the  dyeing  process  is  looselj^  spoken 
of  as  a  "  mordant."  These  should  more  properlj^  be  considered  as  "  assist- 
ants," as  they  do  not  act  in  the  proper  role  of  a  mordant.  The  latter 
term  should  only  be  applied  to  those  materials  which  actually  combine 
with  the  fiber  on  the  one  hand  and  the  dyestuff  on  the  other,  thus  forming 
a  necessary  link  in  the  eventual  color-lake  contained  in  the  fiber.  A  dis- 
tinction must  also  be  drawn  between  the  use  of  metallic  salts  as  mordants 
proper  and  their  use  in  processes  of  after-treatment  of  certain  dj-ed  colors. 
In  some  cases  their  effect  is  to  form  a  more  stable  color-lake  on  the  fiber, 
though  even  here  it  is  doubtful  if  their  action  is  the  same  as  that  of  a  true 
mordant.  In  other  cases,  such  as  with  manj^  colors  where  chrome  is  used 
as  an  after-treatment,  the  effect  is  simply  to  cause  an  oxidation  of  the  dj'e 
to  another  product  which  is  more  insoluble  and  consequently  of  increased 
fastness.  A  good  illustration  of  this  is  the  after-chroming  of  some  of  the 
chromotrope  dyes;  when  applied  directly  as  acid  colors  these  dyes  give 
red  or  brown  colors  which  have  poor  fastness,  but  when  after-chromed 
the  color  is  changed  to  blue  or  black  and  the  fastness  is  greatly  increased. 
The  action  of  the  chrome,  however,  in  such  cases  maj^  be  more  complicated 
than  is  at  first  apparent;  besides  its  chemical  action  on  the  color  we  have 
reason  to  believe  that  the  metallic  base  also  enters  into  some  form  of 
combination  in  the  resulting  color-lake.  This  is  evidenced  by  the  fact 
that  alum  and  bluestone  also  effect  changes  in  the  color  of  certain  dyes 
and  produce  an  increased  fastness  in  a  manner  very  similar  to  that  of 
chrome;  and  in  such  cases  the  effect  cannot  be  due  to  an  oxidation  of  the 
color,  but  rather  to  the  formation  of  a  compound  in  which  the  metallic 
base  enters  as  a  component. 

Generally  speaking,  mordants  are  of  three  classes: 

(a)  metallic  mordants,  such  as  chrome,  alum,  bluestone,  copperas,  tin  salts,  titanium 

salts,  etc. 

(b)  tannin  mordants,  such  as  cutch,  sumac,  tannic  acid,  etc. 

(c)  oil  mordants,  such  as  Turkey-red  oil,  GallipoU  oil,  fatty  acids,  etc. 

The  metallic  mordants  are  salts  of  the  heavy  metals  and  practically 
any  such  salt  maj'  be  employed,  though  naturally  some  are  much  more 
suitable  than  others.     They  may  be  used  to  combine  directly  with  the 

zinc  and  tin  salts  form  with  each  other  compound  mordants  also  insoluble  in  caustic 
alkalies.  It  is  very  ])robablc  that  in  many  cases  compound  mordants  are  produced 
on  the  fiber  either  intentionally  or  accidentall}'.  The  best  mordants  as  far  as  cotton  is 
concerned  appear  to  consist  of  the  sesquioxides  like  those  of  aluminium,  chromium,  and 
iron  in  combination  with  monoxides  like  lime,  magnesia,  or  zinc  oxide.  In  some  cases 
even  treble  mordants  are  used,  like  iron  fixed  with  arsenate  of  soda  and  lime. 


COLOR  AND   CHEMICAL  CONSTITUTION  169 

fiber,  as  in  the  ordinary  process  of  mordanting  wool,  or  they  may  be  used 
in  combination  with  tannin  so  as  to  be  fixed  in  the  fiber,  as  in  mordanting 
silk  and  cotton;  or  further  they  may  be  used  in  combination  with  a  fatty 
acid  for  purposes  of  fixation,  as  in  mordanting  cotton  with  alum  for  dyeing 
Turkey  Red.  It  may  thus  be  seen  that  a  variety  of  chemical  manipula- 
tions may  be  employed  in  order  to  obtain  a  fixation  of  the  metallic  mor- 
dants in  the  fibers. 

The  tannin  mordants  are  used  either  as  indicated  above  for  fixing 
metallic  mordants,  or  more  specifically  as  mordants  in  themselves  for  the 
dyeing  of  basic  colors  on  cotton.  ; 

The  oil  mordants  consist  of  fatty  acids  in  one  form  or  another  and  are 
used  to  rather  a  limited  extent  and  almost  exclusively  for  the  fixation  of 
metallic  bases  in  cotton  dyeing. 

The  range  of  mordants  employed  and  their  application  is  much  more 
extensive  in  printing  than  it  is  in  dyeing.  This  is  due  to  the  fact  that 
these  compounds  may  be  more  readily  applied  and  fixed  in  the  form  of  a 
printing  paste  than  in  the  form  of  a  dilute  aqueous  solution,  such  as  is 
usually  employed  in  dyeing. 

7.  The  Pigment  Dyes. — These  coloring  matters  are  of  a  different 
nature  from  those  of  the  other  groups.  While  the  latter  are  organic  com- 
pounds and  mostly  derivatives  from  coal-tar,  the  pigment  dyes  are  of  a 
mineral  nature.  They  consist,  really,  of  mineral  pigments  precipitated 
more  or  less  mechanically  in  the  fiber.  Chrome  Yellow,  for  instance, 
consists  of  lead  chromate,  a  compound  of  an  intensely  yellow  color  which 
may  be  prepared  entirely  independent  of  the  fiber  and  is  used  extensively 
as  a  pigment  for  the  preparation  of  paints. 

8.  Relation  between  Color  and  Chemical  Constitution. — From  studies 
of  the  chemical  constitution  of  dyestuffs  and  organic  coloring  matters  in 
general,  it  has  become  evident  that  there  is  a  definite  relation  between  the 
color  properties  of  the  compound  and  its  chemical  structure.  It  is  appar- 
ent that  the  presence  of  certain  molecular  groups  is  necessary  in  order 
to  have  a  body  capable  of  forming  a  dyestuff.  Such  molecular  groups  are 
known  as  chromophors.  In  addition  to  this  it  seems  necessary  to  have 
certain  salt-forming  groups  of  a  basic  (amino  group,  NH2)  or  acid  (phenol 
group,  OH)  character  present  in  order  that  the  compound  act  as  a  dyestuff 
in  its  ability  to  color  the  fibers;  these  salt-forming  groups  are  known  as 
auxochromes.  Also  the  chemical  characteristics  of  dyestuff s  are  due  to 
certain  well-defined  groups;  that  is  to  say,  the  chemical  structure  deter- 
mines in  large  degree  whether  the  dye  is  acid,  basic,  substantive,  mordant, 
sulphur,  or  a  vat  dye.  The  character  and  arrangement  of  the  chemical 
groups  also  more  or  less  determine  the  nature  of  the  color,  as  is  well  illus- 
trated in  the  case  of  dyes  derived  from  salicylic  acid  as  a  component; 
all  of  these  dyes  are  either  yellow  or  have  a  strong  yellow  component  pres- 


170 


CLASSIFICATION  OF  DYES 


ent.  Thero  also  appears  to  be  some  relation  between  the  chemical  con- 
stitution of  the  d\Tstiiff  and  its  fastness  properties;  the  presence  of  certain 
g;roups  or  the  arrangement  of  the  molecule  in  a  certain  form  may  make  a 
dyestuff  faster  to  light  or  washing,  for  example.  The  study  of  the  details 
relating  to  the  chemical  structure  of  dyestuffs,  however,  is  a  matter  of 
interest  more  for  the  dyestuff  chemist  and  manufacturer  than  for  the  dyer, 
so  will  not  be  further  considered  at  this  point. 

9.  General  Relations  between  the  Fibers  and  the  Methods  of  Dyeing. — 
(a)  Wool. — More  dj-estuffs,  perhaps,  are  applicable  to  wool  than  to  any 
other  fiber,  and  consequently  the  methods  of  dyeing  are  quite  extensive. 


Fig.  125. — Delahuiity  Circulating  Dyeing  Machine,  Ready  for  Operation. 


In  general,  however,  these  methods  may  be  classified  under  the  following 
groups : 

(1)  Dyeing  in  an  odd  hath,  where  the  dye  liquor  is  given  a  rather 
strong  degree  of  acidity  by  the  addition  of  sulphuric  acid.  This  method  is 
principally  used  for  the  acid  group  of  dj'^estuffs,  though  a  few  of  the  sub- 
stantive dj^es  as  well  as  alizarine  dyes  may  also  be  applied  bj^  this  method. 

(2)  Dyeing  in  a  weakly  acid  hath,  where  the  acidity  of  the  dye  liquor  is 
obtained  by  the  use  of  acetic  acid.  This  method  is  employed  for  most  of 
the  basic  and  substantive  dyes,  and  also  for  the  group  of  eosin  dyestuffs. 
Some  of  the  after-chromed  mordant  dyes  are  also  dyed  in  this  manner. 

(3)  Dyeing  in  a  neutral  hath,  though  usually  sufficient  acetic  acid  must 
be  added  to  correct  the  hardness  of  the  water  used.  Some  of  the  basic 
and  many  of  the  substantive  dyes  are  applied  in  this  manner.     The  dye- 


METHODS  OF   DYEING   WOOL  171 

bath  for  previously  mordanted  wool  to  be  dyed  with  Alizarine  or  wood  colors 
is  also  usually  prepared  in  this  manner. 

(4)  Dyeing  in  an  alkaline  bath  is  a  rather  exceptional  method,  and  is 
only  used  for  the  dyeing  of  Alkali  Blue  on  account  of  the  insolubility  of  its 
free  acid. 

(5)  Previously  mordanting  the  fiber  with  a  metallic  salt  and  subsequently 
dyeing  in  a  fresh  bath.  This  is  the  usual  method  of  applying  the  mordant 
and  natural  wood  colors.  Chrome  and  alum  are  the  chief  salts  used  for 
mordanting. 

(6)  After-treating  the  dyed  color  with  metallic  mordants. — This 
method  is  extensively  used  with  the  acid-dyeing  mordant  colors,  and  cer- 
tain acid  and  substantive  dyes  which  give  faster  colors  by  this  treatment. 
The  after-treatment  takes  place  in  a  separate  bath. 

(7)  Single-bath  method  of  mordanting  and  dyeing. — This  is  merely 
a  modification  of  the  preceding  method,  the  mordanting  salt  (usually 
chrome)  being  added  to  the  dyebath  directly.  This  method  is  coming 
into  rather  extensive  use  as  a  number  of  the  mordant  and  acid  dyes  may 
be  employed  in  this  manner  to  yield  fast  colors. 

(8)  Dyeing  in  specially  prepared  vats. — This  method  is  limited  to 
the  so-called  "  vat  "  colors,  such  as  Indigo,  Indanthrenes,  etc.  The  dye- 
stuff  is  first  reduced  and  then  dissolved  in  an  alkaline  bath. 

(b)  Silk  is  dyed  in  the  same  general  manner  as  its  congener  wool, 
with  the  exception  that  the  dyebath  is  nearly  always  prepared  with  the 
addition  of  boiled-off  liquor,  which  is  the  residual  soap  solution  from  the 
scouring  of  raw  silk  and  contains  a  large  proportion  of  silk-glue.  It 
acts  as  a  regulator  to  the  dyebath  and  keeps  the  silk  soft  and  lustrous. 
Where  boiled-off  liquor  is  not  available,  soap,  glue,  dextrin,  etc.,  are 
employed  as  substitutes.  In  some  rare  cases  a  method  of  so-called  "  dry 
dyeing  "  is  employed  with  silk.  Instead  of  using  water  for  the  dyebath, 
the  coloring  matter  is  dissolved  in  naphtha,  and  the  silk  is  dyed  in  this 
solution.     The  general  methods  of  dyeing  silk  may  be  grouped  as  follows: 

(1)  Dyeing  in  a  bath  containing  boiled-off  liquor  and  acidified  with 
sulphnric  acid. — Most  of  the  acid  dyes  are  applied  in  this  manner,  also 
some  of  the  basic  and  substantive  dyes. 

(2)  Dyeing  in  a  bath  containing  boiled-off  liquor  slightly  "  broken " 
(i.e.,  acidified)  with  acetic  acid. — The  majority  of  the  basic  and  sub- 
stantive dyes  are  used  in  this  manner;  also  the  eosin  dyestuffs. 

(3)  Dyeing  in  a  neutral  or  slightly  alkaline  boiled-off  liquor  bath. — This 
method  is  specially  used  for  the  dyeing  of  Alkali  Blue. 

(4)  Dyeing  in  a  bath  containing  a  small  quantity  of  soap. — This 
method  is  employed  for  the  dyeing  of  delicate  tints  with  basic  dyes. 

(5)  Dyeing  in  a  bath  containing  acetic  acid. — This  is  sometimes  used 
for  acid,   basic,   and   substantive   dyes   where   boiled-off   liquor    is    not 


172 


CLASSIFICATION  OF  DYES 


available,  Tussah  silk  and  spun  silk  is  also  generally  dyed  in  this 
manner. 

Silk  is  usually  brightened  after  dyeing  by  treatment  in  a  bath  of  dilute 
acetic  acid,  squeezing  and  drying  without  washing.  This  treatment  not 
only  brightens  the  color  and  increases  the  luster  but  also  greatly  enhances 
the  "  scroop  "  of  the  fiber. 

(c)  Cotton. — The  principal  classes  of  dyestuffs  applied  to  cotton  are 
the  substantive  and  basic  dyes,  though  the  number  of  processes  by  which 
cotton  may  be  dyed  are  numerous. 

(1)  Dyeing  with  substantive  colors  in  a  neutral  bath  containing  common 

salt  or  glaubersalt.     This  is  the  ordi- 

r.  «,_ „.,  nary  method  of  dyeing  cotton  and  is 

rfT    /  ~^^  "^j  ii         applicable  to  the  majority  of  the  sub- 

stantive dyes. 

(2)  Dyeing  in  a  cold  alkaline  bath. 
— Certain  of  the  substantive  dyes 
may  be  applied  in  this  manner,  the 
dyestuff  usually  being  dissolved  in 
some  caustic  soda,  and  soap  being 
added  to  the  bath. 

(3)  Dyeing  in  a  bath  made  strongly 
alkaline  with  the  addition  of  caustic 
soda.  This  is  a  method  for  the 
dyeing  of  certain  red  substantive 
colors  and  has  a  very  limited  appli- 
cation. 

(4)  Diazotizing  a  dyed  substantive 
color  by  treatment  with  an  acidified 
solution  of  sodium  nitrite  and  sub- 
sequently   treating    unth    a    substance 

known  as  a  developer. — This  is  the  general  method  of  applying  the  so- 
called  developed  dyes,  and  is  extensively  used  for  the  production  of  a  num- 
ber of  fast  colors. 

(5)  Treatituj  a  dyed  substantive  color  with  a  solution  of  diazotized 
paranitr aniline. — This  furnishes  the  class  of  so-called  coupled  colors.  In 
addition  to  paranitraniline  a  few  other  amino  bodies  of  a  similar  nature 
are  employed.  This  method  is  capable  of  producing  some  very  fast  colors, 
but  owing  to  its  complexity  and  expense  it  has  but  a  limited  application. 

(6)  After-treating  a  dyed  substantive  color  with  a  solution  of  a  metallic 
salt. — This  is  for  the  purpose  of  giving  colors  faster  to  washing  and  light. 
The  metallic  salts  almost  exclusively  employed  are  chrome  (potassium 
bichromate)  and  bluestone  (copper  sulphate). 


Fig.  126. — Dyeing  Machine  for  Loose 
Stock.     (Esser.) 


METHODS  OF  DYEING  COTTON  173 

(7)  After-treatment  of  a  dyed  substantive  color  with  formaldehyde. — ■ 
This  process  is  used  principally  with  black  dyes,  and  is  for  the  purpose  of 
making  the  color  faster  to  washing. 

(8)  Mordanting  the  fiber  with  a  tannate  of  a  metallic  salt  and  dyeing 
with  a  basic  color  in  a  fresh  bath  containing  alum  or  acetic  acid. — This 
is  the  general  method  of  applying  the  basic  dyes  and  some  of  the  natural 
dyes.  The  cotton  is  first  treated  with  a  solution  of  tannin  (sumac,  tannic 
acid,  etc.),  then  with  a  solution  of  a  metallic  salt  (usually  tartar  emetic  or 
other  suitable  salt  of  antimony,  though  salts  of  other  metals  such  as  iron, 
copper,  etc.,  may  at  times  be  used),  and  finally  dyed. 

(9)  Dyeing  in  a  neutral  bath  and  subsequently  treating  with  a  mor- 
dant of  tannin  and  antimony. — This  method  of  after-mordanting  is 
used  for  the  class  of  Janus  dyes,  and  has  but  a  limited  application. 

(10)  Topping  a  dyed  substantive  color  with  a  small  amount  of  basic 
dye  in  a  fresh  neutral  bath. — This  method  is  often  employed  for  bright- 
ening and  deepening  the  color  obtained  with  a  substantive  dye;  the  latter 
color  acting  as  a  mordant  for  the  basic  dye. 

(11)  Dyeing  in  an  alkaline  bath  with  the  addition  of  sodium  sulphide. — 
This  is  the  method  generally  employed  for  the  application  of  the  class  of 
sulphur  dyes.  Many  of  these  colors  may  also  be  after-treated  with  solu- 
tions of  metallic  salts  or  topped  with  basic  colors. 

(12)  Dyeing  in  a  specially  prepared  vat  containing  a  reducing  agent. — 
This  method  is  for  the  application  of  Indigo  and  its  various  derivatives,  as 
well  as  the  general  class  of  vat  colors,  such  as  Indanthrene,  Ciba,  Algol,  and 
Helindone  dyes. 

(13)  Dyeing  in  a  bath  containing  alum. — This  is  the  method  of 
applying  some  of  the  acid  dyes  to  cotton;  blue  colors  are  the  chief  ones 
obtained  and  the  method  has  but  a  limited  use. 

(14)  Dyeing  in  a  lukewarm  bath  weakly  acidified  with  acetic  acid. — 
Certain  of  the  basic  dyestuffs,  as  well  as  the  general  class  of  rhodamine 
dyes  are  applied  in  this  manner.  The  colors  produced  are  very  lustrous 
and  bright. 

(15)  Dyeing  in  a  bath  containing  sodium  stannate  and  sulphuric  acid. — 
This  is  a  special  method  for  the  application  of  Soluble  Blue. 

(16)  Mordanting  with  Turkey-red  oil  and  dyeing  in  a  neutral  bath. — 
Bright  pink  colors  can  be  obtained  in  this  manner  with  Rhodamine. 
Various  basic  dyes  may  also  be  applied  by  this  method. 

(17)  Dyeing  in  a  lukewarm  bath  containing  a  large  amount  of  common 
salt. — Light,  bright  colors  can  be  obtained  in  this  manner  by  using  the 
eosin  dyes  and  certain  of  the  acid  dyes. 

(18)  Mordanting  with  soap  and  stannic  chloride  and  dyeing  with  cer- 
tain of  the  basic  colors  for  the  production  of  very  bright  blue  shades. 


174  CLASSIFICATION  OF  DYES 

(19)  Mordanting  with  tannic  acid  and  aluminium  acetate  and  dj'eing 
with  the  rhodamine  dyes  for  the  production  of  bright  pinks. 

(20)  Mordanting  with  alum  and  sodium  stannate  and  dyeing  with 
certain  acid  colors  for  the  production  of  very  bright  scarlet  and  orange 
shades. 

(21)  Mordanting  with  Turkey-red  oil  ami  aluminium  acetate  (or  other 
suitable  aluminium  salt)  and  dyeing  with  Alizarine  Red.  This  is  the 
process  largely  used  for  the  production  of  the  bright,  fast  red  color  known 
as  Turkey  Red.  The  method  of  mordanting  and  dyeing  is  rather  com- 
plicated. Salts  of  chromium  and  iron  may  be  used  in  place  of  almninium 
salts,  and  other  alizarine  dj'es  besides  the  red  may  also  be  used. 

(22)  Preparing  the  fiber  with  heta-naphthol  and  treating  with  diazo- 
tized  'paranitraniline. — This  is  the  method  of  dyeing  the  so-called  azo 
colors  which  are  built  up  in  the  fiber.  Paranitraniline  Red  is  the  principal 
color  of  this  class,  though  a  number  of  other  colors  may  be  obtained  by 
using  certain  other  amino  bodies  in  place  of  the  paranitraniline. 

(23)  Impregnating  the  fiber  with  aniline  and  oxidizing. — This  is  the 
process  of  producing  what  is  known  as  Oxidized  or  Aniline  Black,  and  is 
also  an  example  of  building  up  a  dj^estuff  directly  in  the  fiber. 

(24)  Impregnating  the  fiber  with  the  solution  of  a  metallic  salt  (such  as 
lead  acetate)  and  treating  with  another  chemical  body  capable  of  pro- 
ducing a  colored  pigment  (such  as  chrome). — This  is  the  general  method 
of  producing  the  mineral  or  pigment  colors,  such  as  Chrome  Yellow,  Iron 
Buff,  etc. 

Linen,  ramie  and  the  other  vegetable  fibers  in  general  are  dj'^ed  in  much 
the  same  manner  as  cotton,  though  special  modifications  have  often  to  be 
made  depending  on  the  nature  of  the  fiber  to  be  dyed.  Jute  and  fibei-s  of 
a  ligno-cellulose  nature  differ  from  cotton  in  being  capable  of  combining 
directly  with  acid  and  basic  dj-es  as  well  as  the  substantive  dyes. 

Artificial  silk  (lustra-cellulose)  is  also  a  cellulose  product,  and  it  is 
dj-ed  in  the  same  manner  as  cotton,  though  special  precautions  have  to 
be  adopted,  as  this  fiber  becomes  considerably  weakened  when  wet  out 
with  water. 

Feathei-s,  hair,  paper,  leather,  etc.,  are  also  extensively  dyed. 

10.  Experimental.  Exp.  45.  Action  of  Acid  Dyes. — Prepare  a  bath  containing 
300  cc.  of  water  and  a  few  drops  of  Formyl  \'iolet  solution.  Take  a  scoured  test  skein  of 
woolen  yarn,  wet  it  out  with  warm  water,  and  place  it  in  the  above  bath;  boU  for  one- 
half  hour;  then  wash  well  in  fresh  water  and  dry.  Repeat  this  test,  using  a  bath  con- 
taining 300  cc.  of  water,  5  cc.  of  Formyl  Violet  solution,  and  a  few  drops  of  dilute 
sulphuric  acid  solution.  It  will  be  found  that  in  ths-  first  test  the  wool  is  only  slightly 
dyed,  whereas  in  the  second  test  it  is  well  dyed.  Repeat  the  second  test,  using  a  wet- 
out  test  skein  of  cotton  yarn;  wash  well  and  dry  It  will  be  found  that  the  cotton  is 
only  slightly  tinted  by  the  acid  dyestuff .  Repeat  the  test  again,  using  a  skein  of  boiled- 
off  silk,  and  it  will  be  found  that  the  silk  is  dyed  like  the  wool. 


EXPERIMENTAL  STUDIES 


175 


Exp.  46.  Action  of  Basic  Dyes. — Prepare  a  bath  containing  300  cc.  of  water  and 
5  cc.  of  a  solution  of  Magenta,  and  boil  a  test  skein  of  woolen  yarn  therein  for  one-half 
hour,  then  wash  well  and  dry.  It  will  be  noticed  that  the  dyestuff  is  taken  up  by  the  wool 
directly.  Repeat  the  test,  using  a  skein  of  silk.  It  will  be  found  that  the  silk  also  dyes 
directly  with  the  basic  coloring  matter.  Repeat  the  test  again,  using  a  skein  of  cotton 
yarn.  It  will  be  found  that  in  this  case  the  cotton  is  only  slightly  tinted  with  the 
dyestuff.  Take  a  second  skein  of  cotton  and  work  it  for  one-half  hour  at  180°  F.  in  a 
bath  containing  300  cc.  of  water  and  a  small  amout  of  tannic  acid.  Squeeze,  and  then 
dye  as  before  described  in  a  fresh  bath.  It  will  now  be  found  that  the  treated  cotton 
will  combine  with  the  basic  dyestuff. 

Exp.  47.  Action  of  Substantive  Dyes. — Prepare  a  dyebath  containing  300  cc.  of 
water  and  10  cc.  of  a  solution  of  Benzopurpurin  4B,  and  boil  a  test  skein  of  wool  therein 
for  one-half  hour,  then  wash  well  and  dry.     It  will  be  noticed  that  the  wool  combines 


Fig,  127.— Dyeing  Machine  for  Loose  Stock.     (;Klug 


directly  with  the  substantive  dyestuff.  Repeat  the  test,  using  a  skein  of  silk,  and  it 
will  be  found  that  the  silk  will  also  be  dyed.  Repeat  the  test  again,  using  a  skein  of 
cotton  3'arn;  the  cotton  will  also  be  dyed. 

Exp.  48.  Action  of  Mordant  Dyes.— Dye  a  skein  of  woolen  yarn  in  a  bath  containing 
300  cc,  of  water  and  a  small  amount  of  Alizarine  Red;  boil  for  one-half  hour.  It  is  found 
that  the  dyestuff  is  not  taken  up  to  any  extent  by  the  fiber.  Boil  a  second  skein  of  woolen 
yarn  in  a  bath  containing  10  cc.  of  chrome  solution  (potassium  bichromate)  for  one-half 
hour;  then  rinse  and  dye  as  above  given.  The  dyestuff  will  now  be  absorbed  by  the  mor- 
danted wool,  combining  with  the  chromium  oxide  in  the  fiber  to  form  a  color-lake.  Dye 
a  skein  of  cotton  yarn  with  Alizarine  Red  in  the  above  manner;  it  will  be  found  that  the 
fiber  has  no  attraction  for  the  dyestuff.  Mordant  a  second  skein  of  cotton  yarn  by 
working  in  a  cold  solution  containing  200  cc.  of  water  and  5  grams  of  ferric  chloride 
for  ten  minutes;  squeeze  and  pass  through  a  cold  solution  containing  200  cc.  of  water 
and  2  grams  of  soda  ash.  This  furnishes  a  deposit  of  iron  oxide  on  the  fiber  and  gives 
the  latter  a  buff  color.     Now  dye  this  mordanted  skein  in  the  above  manner  with  Ah- 


176  CLASSIFICATION  OF  DYES 

zarine  Red,  and  it  will  be  found  that  the  dyestulT  is  absorbed  and  the  cotton  becomes 
dyed.  Dye  a  skein  of  silk  with  the  solution  of  Alizarine  Red;  it  will  be  noticed  that 
silk  is  similar  to  wool  and  cotton,  and  is  not  dyed  by  the  alizarine  dye.  Mordant  a 
second  skein  of  silk  with  chrome  in  the  same  manner  as  was  used  for  wool,  and  then  dye 
with  the  Alizarine  Red.  It  will  be  found  that  the  mordanted  silk,  like  the  wool,  will 
combine  with  the  dyestuff. 

Exp.  49.  Action  of  Pigment  Dyes. — Work  a  skein  of  cotton  j'arn  for  fifteen  minutes 
in  a  cold  solution  containing  200  cc.  of  water  and  5  grams  of  lead  acetate.  Squeeze  and 
then  work  for  fifteen  minutes  in  a  second  cold  solution  containing  200  cc.  of  water 
and  2  grams  of  pota.ssium  bichromate.  Wash  well  and  dry.  A  yellow  pigment  con- 
sisting of  Chrome  Yellow  fchromate  of  lead)  will  be  formed  in  the  fiber  through  the 
chemical  reaction  between  the  lead  acetate  and  the  potassium  bichromate.  This  pig- 
ment is  purely  of  a  mineral  nature  and  is  simply  deposited  in  the  cells  of  the  fibers  and 
does  not  combine  with  the  substance  of  the  fiber  itself,  as  is  the  case  with  the  other 
methods  of  dyeing. 


CHAPTER  VI 

APPLICATION  OF  ACID  DYES  TO  WOOL 

1.  General  Characteristics  of  the  Acid  Dyes.* — These  colors  are  the 
principal  dyes  employed  for  the  dyeing  of  woolen  materials,  especially 
yarns  and  piece-goods,  t  Most  of  them  are  level-dyeing;  and  their  general 
fastness  to  washing  and  light  is  good,  though  the  fastness  varies  largely 
with  the  individual  members.  The  acid  dyes,  as  a  rule,  are  cheap  com- 
pared with  the  other  classes  of  dyestuffs  and  considering  their  high  coloring 
power.  In  this  latter  respect,  however,  they  are  not  equal  to  the  basic 
dyes,  though  these  are  more  costly.  Generally  speaking,  the  acid  dyes 
give  very  clear,  fine  tones  of  color  of  great  brightness.  In  this  respect 
they  surpass  the  substantive  and  mordant  dyes,  but  are  inferior  to  the 
basic  dyes.  In  light  shades  very  beautiful  tints  may  be  dyed  with  the 
acid  colors,  especially  if  the  wool  is  first  bleached  in  order  to  furnish  a 
white  basis  for  the  color.  For  full  saturated  shades  the  acid  dyes  usually 
require  the  use  of  3  to  5  per  cent  of  color.  As  to  fastness  of  the  acid 
dyes,  it  is  not  possible  to  lay  down  a  general  rule,  as  this  quality  differs 
widely  with  the  individual  dyes;    many  of  the  acid  dyes,  however,  are 

*  Most  of  the  acid  colors  fall  into  three  chemical  groups:  (a)  nitro  compounds;  (b)  azo 
compounds;  (c)  and  sulphonated  basic  colors.  There  are  also  certain  sulphonated  dyes 
derived  from  anthracene  which  belong  to  the  acid  colors,  such  as  Alizarine  Sapphire.  With 
the  nitro  dyes  the  acid  character  is  due  to  the  presence  of  several  nitro  groups  (NO2)  in 
the  molecule ;  though  in  the  case  of  Naphthol  Yellow  S  there  is  also  present  a  sulphonic 
acid  group  (SO3H).  The  acid  character  of  the  other  dyes  is  due  to  the  presence  of  the 
sulphonic  acid  group,  or  in  some  cases  to  the  carboxyl  group  (COOH),  such  as  in  the 
case  of  the  salicylic  acid  dyes.  Of  late  there  have  appeared  some  acid  dyes  containing 
metallic  radicals,  such  as  chromium  and  copper.  Most  of  the  acid  dyes  occur  com- 
mercially in  the  form  of  their  sodium  (or  potassium)  salts;  the  Patent  Blues,  however, 
occur  as  the  calcium  salts.  About  the  only  dye  to  be  met  with  in  the  form  of  the  free- 
acid  is  Picric  Acid,  and  this  has  very  little  use  as  a  dyestuff  at  the  present  time.  With 
acid-reducing  agents  (zinc  and  hydrochloric  acid  or  stannous  chloride  and  hydrochloric 
acid)  the  acid  dyes  (in  aqueous  solution)  are  decolorized.  The  reduction  of  the  sul- 
phonated basic  dyes  gives  a  leuco  compound  from  which  the  original  dye  may  be  repro- 
duced by  simple  oxidation;  but  with  the  nitro  and  azo  dyes  leuco  compounds  are  not 
formed,  and  consequently  the  original  dye  cannot  be  regenerated  by  oxidation.  The 
nitro  dyes  on  reduction  give  amino  bodies  (N02-^^NH2),  while  the  azo  dyes  on  reduc- 
tion have  the  azo  grouping  ( — N  :  N — )  split  with  the  formation  of  two  amino  bodies 
(— NH2,  — NH2). 

t  The  acid  dyes  are  used  largely  for  the  dyeing  of  suitings,  dress  goods,  knitting  and 
hosiery  yarns  carpet  yarns  and  hat  materials. 

177 


178 


APPLICATION  OF  ACID  DYES  TO  WOOL 


quite  fast  to  light  *  and  to  washing;  as  a  rule,  thoy  will  not  stand  heavy 
fulling.  On  this  account  they  are  more  applicable  to  the  dyeing  of  the 
woven  cloth  (piece  dyeing)  than  to  the  dyeing  of  loose  stock  or  yarn. 
They  are  laigely  used  for  colors  on  ladies'  dress  goods  and  hght  suitings 
and  other  goods  where  heavy  washing  is  not  required. 

One  of  the  chief  defects  of  the  acid  dyes  is  their  tendency  to  bleed  from 
the  dyed  fiber  and  stain  undj'ed  material  when  washed  with  soap,  or  even 


Fig.  128. — Dyeing  Apparatus.     (Psarski.) 


when  steeped  in  warm  water.  This  degree  of  bleeding  is  increased  if  the 
soap  used  is  alkaline  in  character,  for  alkaline  liquors  affect  the  acid  colors 
considerably,  so  much  so,  in  fact,  that  many  of  these  colors  may  be  stripped 
in  great  measure  from  the  fiber  by  boihng  in  a  weak  alkaline  liquor  (such 
as  ammonium  carbonate,  soda  ash,  borax,  etc.).  Treatment  with  strongly 
alkaline  liquors  is  not  to  be  expected,  for  the  wool  fiber  itself  is  rapidly 
destroyed  in  hot  or  boiling  solutions  of  the  caustic  alkahes  or  even  a  moder- 

*  This  is  speciall}'  true  of  the  azo  dyes;  the  acid  greens  and  violets  show  much  less 
fastness  to  light. 


GENERAL  PROPERTIES   OF   ACID   DYES  179 

ately  strong  solution  of  soda  ash  or  potassium  carbonate.  The  sensi- 
tiveness to  alkaUes,  however,  varies  greatly  among  the  different  acid  dyes, 
and  there  are  quite  a  number  which  resist  the  normal  action  of  alkalies 
very  well.  It  is  almost  needless  to  say  that  the  acid  colors  are  quite 
resistant  to  the  action  of  weak  acid  solutions,  seeing  that  the  colors  them- 
selves are  dyed  in  such  liquors. 

In  range  of  color  the  acid  dyes  are  quite  varied,  representatives  of 
almost  every  color  being  available.  Water  of  ordinary  hardness  does  not 
have  much  effect  on  the  acid  dyes,  and  in  the  dyebath  any  tendency  of 
hard  water  to  precipitate  these  colors  is  prevented  by  the  presence  of 
acid.  Material  dyed  with  the  acid  colors  should  be  well  washed  after 
coming  from  the  dyebath,  especially  if  heavy  shades  are  used,  otherwise 
the  color  may  show  unnecessary  bleeding  on  scouring,  or  may  have  the 
defect  of  rubbing  or  "  crocking."  Should  an  acid  color  show  any  ten- 
dency towards  dyeing  unevenly,  the  following  precautions  should  be 
observed  :* 

(a)  Start  the  dyebath  at  a  low  temperature  and  heat  to  the  boiUng  point  only 
very  gradually. 

(b)  Do  not  add  any  acid  until  the  goods  have  been  worked  in  the  dyebath  for 
some  time,  and  then  add  the  acid  in  several  portions  during  the  dyeing. 

(c)  Be  sure  that  the  dyestuff  is  thoroughly  dissolved  and  add  the  solution  in 
several  portions  during  the  dyeing. 

(d)  Do  not  use  too  "  short  "  a  dyebath,  that  is,  one  containing  too  little  water,  f 

*  Dyestuffs  which  show  a  less  degree  of  exhaustion,  as  a  rule,  dye  more  evenly  than 
those  which  exhaust  more  completely,  though,  on  the  other  hand,  the  colors  they 
produce  are  usually  less  fast  to  washing.  A  knowledge  of  the  relative  exhaustion  and 
level-dyeing  properties  of  dyestuffs  is  of  importance  in  selecting  mixtures  of  dyestuffs 
for  the  production  of  compound  colors.  Only  those  dyes  should  be  combined  in  the 
same  bath  which  have  approximately  the  same  degree  of  exhaustion;  otherwise  in  using 
a  standing  bath  the  color  ratio  is  constantly  changing  and  difficulties  will  be  experi- 
enced in  shade  matching. 

t  Dyes  which  exhaust  too  rapidly  often  give  rise  to  uneven  dyeing,  especially  if  the 
bath  is  heated  at  all  unevenly.  This  will  be  particularly  true  if  the  dyestuff  solution 
is  added  to  the  hot  bath  containing  the  wool.  Probably  the  greater  number  of  dyestuffs 
show  a  tendency  to  come  up  unevenly  in  some  degree,  while  the  smaller  number  are  of 
a  very  level-dyeing  nature.  Such  dyes  are  not  confined  to  any  one  class,  but  extend 
through  all  the  different  groups  of  dyestuffs.  Uneven  dyeings,  however,  may  result 
from  a  variety  of  causes.  In  the  manufacture  of  woolen  materials,  wools  of  different 
quality  and  origin  are  mixed  together,  and  it  will  often  happen  that  one  kind  of  wool 
will  have  a  greater  attraction  for  the  coloring  matter  than  another,  hence  will  dye  up  a 
darker  color;  or  sometimes,  one  kind  of  wool  will  take  one  shade,  and  another  kind  of 
wool  a  slightly  different  shade;  hence,  the  dyed  color  may  appear  uneven  from  this 
cause.  For  the  dyeing  of  wool  it  is  desirable  to  use  as  soft  water  as  possible,  though 
this  is  not  so  necessary  as  in  the  case  of  dyeing  silk,  where  it  is  customary  to  employ 
soap  as  an  addition  to  the  dyebath.  That  the  lime  in  hard  water  has  a  certain  influ- 
ence in  dyeing  is  without  doubt,  although  this  effect  is  more  or  less  neutralized  by  the 
presence  of  sulphuric  or  acetic  acid  in  the  dyebath. 


180  APPLICATIOX  OF  ACID  DYES  TO  WOOL 

2.  Preparation  of  the  Dyebath. — For  the  dyeing  of  woolen  yarn  there 
will  be  required  about  sixty  times  the  amount  of  water  or  dye  liquor  as 
there  is  material  to  be  dyed;  that  is  to  say,  1  lb.  of  woolen  yarn  Avili 
require  about  7.5  gallons  of  water  in  the  dyebath  (1  gallon  of  water  weighs 
8^  lbs.).  Silk  will  also  require  about  the  same  proportion.  Cotton  j'-arn, 
on  the  other  hand,  will  require  only  about  one-half  the  amount  of  dye 
liquor  as  wool;  that  is  to  say,  1  lb.  of  cotton  may  be  dyed  in  about  3^ 
gallons  of  dye  Hquor.* 

In  dyeing  wool  with  the  acid  dyestuffs,  it  is  customary  to  use  the  fol- 
lowing general  formula  in  the  preparation  of  the  bath: 

4  per  cent  of  sulphuric  acid,  f 

20  per  cent  of  glaubersalt, 

X  per  cent  of  dyestuff    (in  necessary  amount   to   produce  the  color 
desired). 

While  this  is  to  be  considered  a  general  method  applicable  to  almost  any 
of  the  acid  dyes,  it  may  be  varied  somewhat  as  occasion  requires  with 
the  use  of  particular  dyestuffs. 

Instead  of  glaubersalt  and  acid,  sodium  bisulphate  itself  may  be  used 
with  the  same  general  effect;  in  which  case  about  15  per  cent  is  employed 
(as  this  will  furnish  about  4  per  cent  of  free  sulphuric  acid).  J 

The  proper  regulation  of  the  temperature  of  the  dyebath  is  also  to  be 
considered.  While  for  most  purposes  of  dyeing  it  is  necessary  to  boil  the 
material  in  the  dyebath  for  at  least  one-half  to  one  hour  in  order  to  obtain 
proper  penetration  and  fixation  of  the  coloring  matter,  it  is  also  frequently 
inadvisable  to  enter  the  wool  when  the  dj'e  liquor  is  at  a  boiling  tempera- 
ture, as  this  may  lead  to  uneven  and  superficial  dyeing.  In  a  general  way 
it  may  be  said  that  the  most  suitable  temperature  to  start  the  acid  dyebath 
is  about  140°  r.§ 


*  The  porcelain  beakers  employed  for  the  d5'e-tests  described  in  this  book  should 
conveniently  hold  about  300  cc.  of  water;  consequently  they  are  of  a  convenient  size  for 
the  dyeing  of  5-gram  skeins  of  woolen  yarn  or  10-gram  skeins  of  cotton  yarn,  so  that 
the  woolen  and  cotton  skeins  employed  for  the  tests  should  be  supplied  in  these  weights 
respectively.  For  silk,  skeins  of  about  2  grams  weight  may  be  employed  (for  economj'), 
consequently  for  such  tests  only  about  12.5  cc.  of  dye  liquor  should  be  used. 

t  In  formulas  relating  to  the  application  of  dyestuffs,  unless  otherwise  specified,  the 
percentages  refer  to  the  weight  of  the  material  being  dyed;  100  lbs.  of  wool,  for  example, 
would  require  4  lbs.  of  sulphuric  acid  and  20  lbs.  of  glaubersalt. 

t  In  the  case  of  dj'cing  carbonized  goods  which  have  not  been  neutralized  with 
alkali,  and  which  in  consequence  are  still  of  an  acid  character,  it  is  best  to  start  the  dye- 
bath with  glaubersalt  only,  adding  a  little  sodium  bisulphate  or  acid  later  on  if  nec- 
essary. 

§  In  the  dyeing  of  piece-goods  that  are  hard  to  penetrate  it  is  well  to  increase  the 
amount  of  glaubersalt  in  the  bath  and  also  to  enter  the  goods  at  a  somewhat  lower 
temperature.     In  the  case  of  goods  containing  kempy  wool  fibers  that  are  difficult  to 


PREPARATION   OF  THE   ACID   DYEBATH  181 

It  is  nearly  always  necessary  to  boil  the  goods  in  the  dyebath 
in  order  to  obtain  a  proper  fixation  of  the  color  even  though 
the  full  shade  of  the  dye  may  apparently  be  developed  at  a  lower 
temperature  or  with  only  a  slight  degree  of  boiling.*  It  must  be 
remembered  that  the  wool  fiber,  is  a  sort  of  hardened  glue-like  filament 
which  becomes  softened  and  rendered  absorbent  by  prolonged  treatment 
with  boiling  water,  and  that  it  is  the  purpose  of  the  dyeing  operation 
to  cause  the  dyestuff  solution  to  penetrate  the  innermost  parts  of  the  fiber 
and  also  to  assure  as  complete  an  absorption  of  the  coloring  matter  as  pos- 
sible by  the  substance  of  the  cell-walls  of  the  fiber.  By  using  a  cool 
dyebath  or  not  l^oiling  sufficiently,  there  will  be  a  tendency  to  have  the  dye- 
stuff  taken  up  only  superficially,  and  also  there  will  be  incomplete  com- 
bination between  the  color  and  the  colloidal  jelly-like  mass  of  the  fiber. 
It  will  also  frequently  be  found  that  with  insufficient  boiling  the  color 
will  come  up  uneven  or  "  shattery,"  whereas  this  defect  may  be  remedied 
by  longer  boiling.  It  is  not  desirable,  on  the  other  hand,  to  boil  the  bath 
too  vigorously  or  too  long,  as  this  will  result  in  injury  to  the  fiber  through 
felting;  the  bath  is  best  maintained  at  a  simmer,  a  violent  ebullition  being 
avoided. 

There  are  several  variations  from  the  typical  formula  for  dyeing  acid 
colors;  instead  of  preparing  the  bath  with  all  of  its  ingredients  to  start 
with,  the  bath  may  be  made  up  with  only  the  color  solution  and  the 
glaubersalt;  the  goods  are  introduced  at  the  usual  temperature  of  140°  F. 
and  the  temperature  is  gradually  raised  to  the  boiling  point.  During  the 
period  of  the  dyeing  the  acid  is  added  in  several  successive  portions,  and 
this  causes  a  more  gradual  feeding  on  of  the  color.  This  method  is  gen- 
erally employed  in  the  case  of  dyes  having  poor  level-dyeing  properties, 
or  in  the  case  of  goods  where  penetration  is  difficult  and  it  is  necessary  to 
have  the  dye  feed  on  very  slowly  in  order  to  secure  uniform  coloring.  It 
is  also  well  to  use  this  method  in  the  dyeing  of  carbonized  shoddy  or 
"  extract  "  wool,  consisting  of  fiber  which  has  been  already  treated  with 
acid.  With  this  kind  of  material  the  fiber  already  has  an  acid  char- 
acter, and  if  further  immediate  additions  of  acid  are  made  to  the  bath,  the 
color  may  be  taken  up  too  quickly  to  give  good  results. 

Another  variation  of  the  general  method  is  to  replace  the  sulphuric 
acid  with  a  milder-acting  acid,  acetic  acid  being  the  one  most  usually 

dye  through  it  is  recommended  to  keep  the  bath  at  a  Hvely  boil  and  also  to  add  a  httle 
further  acid  toward  the  end  of  the  dyeing. 

*  In  the  use  of  acid  dyes  for  purposes  of  shading  when  dyeing  to  match  a  color,  care 
must  be  taken  to  use  only  the  best  level-dyeing  dyes  when  the  additions  of  dyestuff 
are  to  be  made  in  the  boiling  bath,  otherwise  the  added  color  will  be  taken  up  too  quickly 
to  give  even  results.  If  it  is  not  possible  to  use  the  very  level-dyeing  dyes,  the  dye- 
bath will  have  to  be  cooled  down  somewhat  before  adding  the  color. 


182  APPLICATION  OF  ACID  DYES  TO  WOOL 

emploj^d,  although  of  late  years,  formic  acid  has  also  been  used  for  this 
purpose  with  very  good  results.*  The  action  in  this  case  is  simply  to 
weaken  the  acid  strength  of  the  bath  and  this  has  the  same  retarding 
influence  on  the  absorption  of  the  color.  From  3  to  5  per  cent  of  acetic 
acid  may  be  used,  or  from  2  to  4  per  cent-  of  formic  acid.  It  is  to  be  noted 
that  the  latter  acid  is  more  energetic  in  its  reaction  than  the  former. 
Frequently,  in  order  to  obtain  a  more  satisfactory  exhaustion  of  the 
dyebath,  it  is  necessary  to  add  some  sulphuric  acid  (usually  from  1  to  2 
per  cent)  towards  the  end  of  the  dyeing.  This  is  probably  explained  by 
the  fact  that  the  organic  acids  like  acetic  and  formic  acids  are  volatile 
in  the  boiling  dj^ebaths,  and  consequently  the  latter  gradually  loses  its 
acidity  on  boiling;  whereas  sulphuric  acid,  not  being  volatile,  under 
these  conditions  keeps  the  bath  acid  even  after  prolonged  boiling.  It  is 
also  to  be  borne  in  mind  that  both  acetic  and  foniiic  acids  are  considerably 
more  costly  than  sulphuric  acid,  therefore  economy  will  demand  that  they 
be  used  to  substitute  the  latter  acid  to  the  least  degree  possible. 

For  the  purpose  of  obtaining  a  very  gradually  developed  aciditj^  in  the 
bath  in  cases  where  extreme  precautions  must  be  taken  to  produce  even 
and  well-penetrated  dyeings,  the  substitution  of  the  acid  by  ammonium 
acetate  f  or  sulphate  has  been  suggested.  These  salts  gi-adually  disso- 
ciate in  a  boiling  solution,  and  as  the  annnonia  is  highly  volatile,  the  bath 
will  gradually  develop  acidity  on  boiling,  while  maintaining  a  practically 
neutral  condition  at  lower  temperatures.  The  acetate  is  more  reactive  in 
this  way  than  the  sulphate.  To  obtain  sufficient  acidity,  however,  it  is 
usually  necessary  to  employ  considerable  amounts  of  the  ammonium  salts 
(from  5  to  10  per  cent  of  the  acetate  and  40  to  80  per  cent  of  the  sulphate), 
and  as  these  salts  are  relatively  costly,  their  use  in  this  connection  will  be 
limited  to  very  few  occasions,  such  as  in  the  dyeing  of  heavily  fulled  cloth 
or  very  hard,  tightly  twisted  yarns  where  good  color  penetration  cannot 
be  obtained  by  other  methods.  Also  the  use  of  this  method  requires  a 
very  prolonged  boiling  of  the  goods.  In  this  connection  it  might  be  noted 
that  a  solution  of  ammonium  acetate  wall  usually  strip  down  an  acid 

*  Formic  acid  is  coming  into  use  for  the  dyeing  of  woolen  piece-goods  containing 
cotton  or  artificial  silk  effect  threads  which  it  is  desired  to  leave  white.  In  order  to 
prevent  these  effect  threads  from  becoming  stained  the  goods  must  be  dyed  in  a  strongly 
acid  bath,  and  formic  acid  is  most  suited  for  this  purpose  as  its  acidity  is  very  strong 
(much  greater  than  acetic  acid)  and  at  the  same  time  it  does  not  have  the  same  tender- 
ing effect  on  the  cotton  or  artificial  silk  as  sulphuric  acid.  In  the  dyeing  of  such  goods, 
however,  they  should  be  well  rinsed  immediatclj'  after  dyeing,  and  they  should  be 
dried  as  soon  as  possible;  for  if  loft  for  any  length  of  time  in  the  wet  state  the  dye  is 
liable  to  bleed  from  the  wool  and  stain  the  white  effect  threads. 

t  Ammonium  acetate  is  made  by  mixing  4  parts  of  ammonia  (24  per  cent)  with  10 
parts  acetic  acid  (30  per  cent).  This  solution  will  be  slightly  alkaline  to  litmus,  but 
this  is  of  no  disadvantage  in  dyeing. 


ACIDS  USED   IN   THE   DYEBATH 


183 


color  to  a  considerable  degree,  and  on  this  account  has  no  doubt  a  specific 
action  in  retarding  the  dyeing  operation.  A  special  use  of  this  method, 
however,  is  in  the  dyeing  of  wool  and  silk  mixed  goods  when  it  is  desirable 
to  have  the  acid  dyes  take  up  only  on  the  wool  and  leave  the  silk  colorless. 
To  obtain  this  result  the  use  of  ammonium  acetate  in  place  of  acid  is  very 
satisfactory. 

In  the  case  of  certain  of  the  acid  dyes,  the  acid  may  be  entirely  omitted 
and  a  neutral  bath  be  employed.*  The  dyes,  however,  that  are  capable 
of  being  used  by  this  method  are  quite  limited,  and  the  method  is  only  used 
in  special  cases,  such  for  instance  as  in  dyeing  wool  and  cotton  mixtures 


Fig.  129. — Rhodes  Dyeing  Machine. 


(union  goods),  where  a  substantive  dye  is  used  for  coloring  both  fibers  and 
it  is  necessary  to  shade  somewhat  the  wool  by  the  use  of"  a  neutral  dyeing 
acid  color,  the  use  of  acid  not  being  desirable  in  the  bath. 

A  special  modification  of  the  type  formula  for  acid  dyes  is  the  use  of 
stannic  chloride  (1  to  2  per  cent)  in  the  bath  in  addition  to  the  acid  and 
glaubersalt.  This  is  for  the  purpose  of  obtaining  more  brilhant  colors 
with  certain  dyes.     In  this  connection  it  is  necessary  to  avoid  the  use  of 

*  In  dyeing  carbonized  goods  with  AlkaH  Blue  care  must  be  taken  that  the  acid 
in  the  material  is  first  completely  neutralized  before  entering  the  dyebath,  as  otherwise 
there  will  be  danger  of  some  of  the  dye  being  precipitated  on  the  goods.  The  same 
precaution  should  be  observed  in  the  dyeing  of  shoddy  goods  where  the  fiber  may  have 
been  treated  with  acid  solutions, 


184 


APPLICATION  OF  ACID  DYES  TO  WOOL 


stannous  chloride  (Avhich  is  frequently  present  in  the  stannic  compound), 
as  this  reduces  and  destroys  many  of  the  acid  dyes  (the  azo  colors) .  The 
addition  of  alum  (G  to  8  per  cent)  to  the  bath  is  also  made  at  times  for  this 
same  purpose. 

3.  Function  of  the  Chemicals  Employed  in  Dyeing  Acid   Colors. — 
These  chemicals  arc  mostly  confined  to  sulphuric  acid  and  (jluubcrsalt. 


Fig.  130. — Dyeing  Machine  for  Loose  Stock.     (Obermaier.) 

As  explained  bj^  the  <>;enoral  theory  of  dyeing;,  the  sulphuric  acid  is  used  for 
the  purpose  of  liberating  the  color-acid  of  the  dyestuff  *  so  that  it  may 

*  Apparent!}^  the  acid  exerts  other  influences  besides  the  one  of  simplj-  hberating 
the  color-acid.  For  instance,  in  dj^eing  with  2  per  cent  of  Crystal  Scarlet  only  0.2  per 
cent  of  acid  would  be  necessary  to  split  off  the  free  color-acid;  but  if  this  amount 
of  sulphuric  acid  is  used  in  the  bath  a  light  shade  onlj'  of  the  color  is  obtained.  In 
order  to  produce  a  full  shade  and  obtain  satisfactory  exhaustion,  a  much  larger  quan- 
tity of  acid  is  required;  in  fact  it  takes  thirty  to  forty  times  as  much  acid  to  obtain 
maximum  results  as  would  be  required  to  simply  split  off  the  free  color-acid — that  is 
to  say,  from  2  to  4  per  cent  of  sulphuric  acid  is  used.  The  acid  in  the  dyebath  also 
apparently  reacts  with  the  wool  itself,  for  it  has  been  shown  (Jour.  Soc.  Dyers  it  Col., 
1888,  page  107)  that  if  wool  is  boiled  with  10  j^er  cent  of  sulphuric  acid  and  then  boiled 
out  nine  times  with  100  times  its  own  weight  of  water,  until  the  water  is  perfectly  neu- 
tral in  reaction,  it  will  dj-e  a  heavier  shade  with  2  per  cent  of  Crystal  Scarlet  than 
another  sample  of  untreated  wool  with  the  same  quantitj-  of  dj-estuff,  even  with  the 
addition  of  2^  per  cent  of  sulphuric  acid  to  the  dyebath. 


ACTION   OF   CHEMICALS   IN   ACID   BATH  185 

more  readily  combine  with  the  basic  component  of  the  fiber;  hence  the 
addition  of  the  acid  faciUtates  the  dyeinjz;  and  increases  the  exhaustion  of 
the  l^ath.  Some  acid  dyes  naturally  require  more  acid  than  others  to 
give  the  same  degree  of  exhaustion,  but  4  per  cent  (on  the  weight  of  the 
wool)  appears  to  be  ample  for  almost  all  cases.  The  dyer  does  not 
vary  the  amount  of  acid  with  each  individual  dyestuff  or  variation 
in  quantity  of  dyestuff  used,  but  adheres  to  the  fixed  quantity  of  4  per 
cent.  Sometimes  a  better  degree  of  exhaustion  may  be  obtained  by 
the  addition  of  a  further  quantity  (about  2  per  cent)  of  acid  near  the 
completion  of  the  dyeing  operation.  Some  of  the  acid  dyes  do  not  require 
the  addition  of  such  a  strong  acid  as  sulphuric  to  liberate  the  color-acid, 
but  give  very  good  results  with  a  milder  acid,  such  as  the  organic  acetic 
acid.  Formic  acid  may  also  be  used.  Such  colors  are  especially  useful 
for  the  dyeing  of  wool-cotton  fabrics,  as  the  cotton  is  not  injured  by  the 
acetic  or  formic  acid.  Nearly  all  of  the  acid  colors  are  slightly  dissociated 
on  dissolving  in  water;  that  is  to  say,  a  small  amount  of  the  free  color- 
acid  is  formed;  hence  a  certain  degree  of  dyeing  takes  place  even  without 
the  addition  of  acid.  Some  of  the  acid  dyes  are  largely  dissociated  in 
solution,  and  consequently  these  may  be  dyed  in  a  neutral  bath.  Such 
colors  are  also  useful  for  wool-cotton  dyeing.  Therefore  the  acid  dyes 
may  be  divided  into  three  groups  with  reference  to  the  required  acidity  of 
the  dyebath: 

(a)  Dj-es  which  may  be  applied  in  a  neutral  bath. 

(b)  Dyes  which  require  a  slightly  acid  bath;   usually  acetic  acid  being  employed. 

(c)  Dyes  which  require  a  bath  acidulated  with  sulphuric  acid. 

The  glauhersalt  used  in  the  dyebath  may  exert  an  influence  in  several 
different  ways: 

in)  In  mechanically  retarding  the  interaction  between  the  color-acid  and  the  fiber. 
(6)  In  chemically  retarding  the  liberation  of  the  color-acid  from  the  dye-salt, 
(c)  In  affecting  the  solubility  of  the  dyestuff  in  the  solution. 

The  first  effect  will  be  considered  under  the  general  theory  of  dyeing 
(Chapter  XXV),  and  is  very  likely  the  chief  influence  exerted  by  the  glauher- 
salt. There  is  a  considerable  possibility,  however,  that  a  chemical  action 
may  come  into  play.  It  is  a  well-established  principle  in  chemistry  that 
when  one  of  the  products  of  a  chemical  reaction  is  present  in  the  solution, 
the  rapidity  and  extent  of  this  reaction  will  be  reduced.  Now,  in  the 
interaction  between  sulphuric  acid  and  the  dj^estuff  (which  is  generally 
the  sodium  salt  of  the  color-acid)  glaubersalt  is  formed;  hence,  if  a  rela- 
tively large  proportion  of  glaubersalt  is  already  present,  the  reaction 
between  the  acid  and  the  dyestuff  will  be  considerably  retarded.  Just 
to  what  extent  this  influence  of  the  glaubersalt  affects  the  even  dyeing  of 
the  acid  colors  is  a  question ;  but  it  is  doubtful  if  it  is  as  important  as  the 


186 


APPLICATION  OF  ACID  DYES  TO  WOOL 


preceding  influence.  As  to  the  degree  in  which  the  glaubersalt  affects 
the  solubiUty  of  the  dyestuff  in  the  solution,  it  may  be  stated  that  this 
must  be  rather  hmited,  when  it  is  considered  that  both  the  dyestuff  and 
the  glaubersalt  are  in  rather  dilute  solutions.  The  general  effect  of  the 
addition  of  glaubersalt  to  a  dyestuff  solution  would  be  to  lessen  the  solu- 
bility of  the  dye ;  but  in  order  for  this  effect  to  be  marked  the  concentra- 
tion of  the  glaubersalt  in  the  solution  would  have  to  be  rather  high.  If 
the  glaubersalt  did  act  in  this  manner  in  the  ordinary  dyebath,  the  effect 
would  be  to  throw  the  dyestuff  out  of  solution  and  hence  to  promote 
uneven  rather  than  level  dyeing;  whereas  we  know  the  opposite  to  be  the 
case.     Furthermore,  many  of  the  acid  dyes  may  be  partially  stripped  from 


Fig.  131. — Dyeing  Machine  for  Loose  Stock.     (Schmidt.) 

the  fiber  by  boiling  in  a  bath  containing  glaubersalt;  much  more  of  the 
dyestuff  being  dissolved  than  if  plain  boiling  water  were  used. 

Glaubersalt  is  the  common  name  for  crystallized  sodium  sulphate; 
it  has  the  chemical  formula  Na2S04- IOH2O.  Calcined  or  desiccated 
glaubersalt  has  the  water  of  crystallization  removed  by  heating;  it  is  a 
white  amorphous  powder,  having  the  formula  Na2S04.  About  44  parts 
of  desiccated  glaubersalt  are  equivalent  to  100  parts  of  the  crystalline  salt. 

4.  Exhaustion  and  Leveling  Properties. — The  acid  dyes,  as  a  rule, 
exhaust  fairly  well,  though  this  quality  varies  with  individual  members  of 
the  group.  The  exhaustion  of  the  dyebath  may  usually  be  considerably 
increased  by  the  addition  of  extra  acid  towards  the  end  of  the  dyeing  oper- 
ation.    In  case  the  bp-th  doeg  not  exhaust  wgll,  it  should  be  kept  as  a, 


CALCULATIONS  USED  IN  DYEING  187 

"  standing;  kettle,"  that  is,  preserved  for  further  use  and  freshened  up  by 
the  addition  of  the  necessary  amount  of  dyestuff.  Of  course,  the  poorer 
the  exhaustion  of  the  dyebath  the  less  will  be  the  amount  of  the  second 
addition  of  dyestuff.  Generally  speaking,  with  -the  third  or  fourth  sue- 
cessive  bath,  the  amount  of  dyestuff  to  be  added  each  time  will  become 
constant  in  order  to  produce  the  same  shade.  Most  of  the  acid  dyes  will 
give  a  "  full  shade  "  (in  a  starting  bath)  with  about  3  to  5  per  cent  of  color. 
By  a  full  shade  is  meant  the  maximum  depth  of  color  given  by  a  dyestuff. 

When  it  is  necessary  to  use  copper  vessels  or  machines  in  the  dyeing 
of  acid  colors  on  wool  in  light  or  bright  shades,  to  obtain  the  best  results 
about  3  oz.  of  ammonium  sulphocyanide  should  be  added  per  100  gallons 
of  dye  liquor.  This  is  due  to  the  fact  that  the  acid  in  the  dyebath  will 
dissolve  some  of  the  copper  and  this  will  then  react  with  the  sulphur 
present  in  the  wool  fiber  to  give  a  black  copper  sulphide,  thus  dulling  the 
dyed  shade.  The  presence  of  the  ammonium  sulphocyanide  prevents  the 
formation  of  the  copper  sulphide. 

5.  Calculations  Used  in  Dyeing. — The  amounts  of  dyestuffs  and 
chemicals  employed  in  dyeing  are  usually  expressed  in  terms  of  percentages 
on  the  weight  of  the  material  to  be  dyed.  Thus  in  Exp.  50,  "  20  per  cent 
of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and  1  per  cent  of  Acid  Magenta" 
are  called  for;  this  would  mean  that  the  actual  amounts  of  the  substances 
to  be  taken  are  to  be  the  respective  percentages  on  the  weight  of  the  yarn 
dyed,  wliich  in  this  case  is  5  grams.     Therefore  we  have : 

5  grams X. 04  =  0.20  gram  for  the  sulphuric  acid, 
5  grams X. 20  =  1.00  gram  for  the  glaubersalt, 
5  grams X. 01  =0,05  gram  for  the  dyestuff. 

As  these  are  rather  small  amounts  to  be  continually  weighing  out,  it 
is  best  to  have  the  chemicals  and  dyestuffs  employed  in  the  dye-tests 
made  up  in  solutions  of  such  strength  that  convenient  volumes  will  con- 
tain the  requu'ed  amounts  as  needed  for  the  preparation  of  the  dyebaths. 
As  4  per  cent  is  the  customary  amount  of  sulphuric  acid  to  employ,  a  con- 
venient solution  would  be  one  of  such  strength  that  10  cc.  would  contain 
4  per  cent  of  the  acid  on  5  grams  (this  being  the  weight  of  the  woolen  yarn 
emploj'ed  in  all  the  tests).  To  prepare  1  liter  or  1000  cc.  of  this  solution, 
proceed  as  follows: 

10  cc.  is  to  contain  4  per  cent  on  5  grams  =  0.2  gram  acid. 
1000  cc.  would  therefore  contain  20  grams  acid. 

As  the  commercial  concentrated  sulphuric  acid  has  a  density  of  about  1.84 
(i.e.  1  cc.  weighs  1.84  grams),  20  grams  by  weight  of  the  acid  would  be 
equivalent  to  20-1-1.84  =  11.9  cc.  Hence  the  solution  should  contain 
11.9  cc.  of  the  concentrated  sulphuric  acid  per  liter.     The  solution  of  glau- 


188  APPLICATION  OF  ACID  DYES  TO  WOOL 

bersalt  may  be  pi-opared  in  a  similar  manner.  A  convenient  strenjith  is 
one  containing  20  per  cent  of  the  salt  on  5  grams  in  10  cc.  which  would  be 
1  gram  in  10  cc,  or  100  grams  per  liter.  A  convenient  strength  for  the 
solutions  of  dyestuffs  is  5  grams  per  liter;  hence  1  per  cent  on  5  grams 
would  be  equivalent  to  10  cc.  of  the  solution.  For  a  10-gram  skein,  where 
cotton  yarn  is  employed  in  the  tests,  20  cc.  would  be  equivalent  to  1  per 
cent. 

6.  General  Remarks  on  the  Dyeing  of  WooL — Wool  may  be  dyed  in 
any  of  its  stages  of  manufacture,  i.e.,  as  loose  wool  or  stock,  as  slubbing,  as 
yarn,  or  as  the  woven  piece.  But  in  whatever  form  it  may  come  to  the 
dyer,  it  is  necessary  that  the  fiber  be  as  clean  as  possible ;  that  is,  it  must 
be  thoroughly  scoured.  In  order  to  obtain  uniformity  of  results  it  is  best 
that  the  dyer  should  scour  the  material  himself  before  attempting  to  dye 
it,  as  very  frequently  imperfect  dyeing  results  from  taking  too  much  for 
granted  in  the  matter  of  scouring. 

In  some  cases,  where  a  pure  and  high-grade  fabric  is  desired,  it  is 
required  to  carbonize  wool  stock  before  dyeing.  This  is  for  the  purpose 
of  remo^'ing  the  vegetable  matter,  burrs,  straw,  grass,  etc.,  from  the  fiber 
(see  page  74).  Sometimes  instead  of  carbonizing  the  wool  in  the  loose 
state,  the  removal  of  the  vegetable  matter  does  not  take  place  until  the 
wool  has  been  woven  aud  dyed  in  the  piece.  This  is  usually  done  in  the 
ease  of  high-grade  wools  which  on  dyeing  in  dark  shades  (especially  blacks 
and  blues)  show  little  undyed  specks  due  to  the  accidental  presence  of 
vegetable  fibers.  The  cloth  is  treated  with  acid,  dried,  and  washed 
for  the  purpose  of  carbonizing  much  in  the  same  manner  as  already 
descril>ed  for  loose  wool.  Either  a  solution  of  sulphuric  acid  (2  to  4°  Tw.) 
is  used,  or  gaseous  hydrochloric  acid.  Of  course,  the  dj'es  used  must 
be  such  as  to  resist  the  action  of  the  carbonizing  process.  In  lower  grade 
woolen  cloths  the  vegetable  specks  are  usually  covered  up  by  what  is 
known  as  "  speck  dyeing,"  which  is  mosth'  confined  to  blacks.  The  goods 
are  run  through  a  bath  containing  LogAvood,  bluestone,  and  soda  ash,  which 
dyes  the  specks  of  vegetable  matter. 

When  light,  bright,  and  delicate  colors  are  to  be  obtained  on  loose 
wool,  it  is  general!}'  necessary  to  employ  bleached  stock.  The  bleaching 
is  done  in  the  usual  manner  as  described  on  page  108. 

7.  Dyeing  Wool  in  the  Loose  Stock. — When  dyed  in  the  stock  it  must 
be  borne  in  mind  that  the  wool  must  subsequently'  be  carded,  spun,  woven, 
scoured,  and  finished;  therefore  it  is  necessary  to  select  a  method  of  dyeing 
which  will  yield  a  color  capal^le  of  withstanding  the  various  treatments 
to  which  the  fiber  must  be  subjected.  It  is  necessarj'-  that  the  color  be 
fast  to  crocking  and  scouring  at  least;  hence  it  is  customary  to  employ 
fast  colors  for  the  dyeing  of  wool  stock.  However  fast  the  color  may  be 
it  is  almost  impossible  to  prevent  some  difference  occurring  in  the  shade 


DYEING  LOOSE  STOCK 


189 


as  dyed  on  the  stock  and  that  which  the  finished  fabric  assumes.  This  is 
more  or  less  due  to  the  difference  in  the  mechanical  distribution  of  the 
fibers  after  spinning  and  weaving,  usually  having  the  effect  of  darkening 
the  color.  Wool  dyed  in  the  stock  will  also  be  more  or  less  uneven  in 
shade,  due  to  unevenness  in  the  character  of  the  fiber  throughout  the 
mass  of  the  wool,  causing  different  parts  to  take  up  the  dyestuff  some- 
what differently.  In  the  subsequent  carding  process,  this  unevenness  is 
remedied  by  the  thorough  mixing  of  the  different  fibers,  but  at  the  same 
time  the  shade  of  the  entire  mass  may  suffer  considerable  alteration. 
Therefore  it  is  readily  understood  that  it  is  difficult  to  dye  wool  in  the 


Fig.  132. — Dyeing  Machine  for  Loose  Stock.     (Dreze-Michaelis.) 


stock  so  as  accuratel.y  to  match  a  given  shade  in  the  finished  piece,  it 
being  necessary  to  make  a  proper  allowance  for  the  alteration  which  the 
color  must  suffer  during  the  process  of  manufacture. 

Wool  is  more  perfectly  dyed,  however,  in  the  loose  state  than  in  its 
other  forms.  This  is  due  to  the  fibers  being  more  free  and  open,  conse- 
quently more  directly  exposed  to  the  action  of  the  dye  liquor,  and  allowing 
of  a  better  absorption  and  penetration  of  the  dj^estuff  into  the  fiber.  For 
the  same  reason,  wool  stock  requires  more  dyestufT  to  be  used  for  a  given 
shade  than  yarn  or  cloth;  and  this,  together  with  the  fact  that  fast  dyes 
must  be  employed,  causes  loose  wool  dyeing  to  be  more  expensive  in 
th3  matter  of  drugs.  There  is  also  always  more  or  less  felting  of  the  fibers 
when  wool  is  dyed  in  the  stock.,  and  a  consequent  deterioration  and  loss 


190  APPLICATION  OF  ACID  DYES  TO  WOOL 

during  the  subsequent  carding,  drawing,  and  spinning  processes,  which  is  a 
further  item  of  increased  expense  to  be  attached  to  this  method  of  dj'eing. 
The  chief  purpose  of  dyeing  wool  in  the  stock  is  for  the  manufacture 
of  mixes  and  fancy  yarns,  Tlie  mixes  are  obtained  by  carding  a  certain 
proportion  of  colored  wool  with  white  wool  (oxfords,  grays,  etc.),  or  several 
colors  may  be  carded  together  for  producing  compound  shades.  If  por- 
tions of  yellow  and  blue  wools,  for  instance,  be  carded  together  and  thor- 
oughly mixed,  a  very  uniform  resultant  color  is  obtained,  which  in  this  case 
would  be  green.  This  is  caused  by  the  eye  not  being  able  to  distinguish  the 
separate  colors  of  two  or  more  fibers  in  juxtaposition,  but  only  perceives 
the  blended  or  compound  color. 

8.  Dyeing  Tops  and  Slubbing. — In  its  dyeing  relations  slubbing  or  tops 
is  very  similar  to  wool  stock.  As  it  contains  a  small  quantity  of  oil  added 
for  the  purpose  of  carding  or  combing,  it  is  often  necessary  to  give  it  a 
mild  scouring  preliminary  to  dyeing.  Worsted  tops  are  dyed  very  exten- 
sively in  special  machines,  the  object  being  to  leave  the  fibers  as  free  as 
possible,  so  as  to  avoid  loss  and  bad  work  in  the  subsequent  drawing  and 
spinning  operations.  As  worsted  materials,  as  a  rule,  are  not  very  heavily 
fulled  in  finishing,  and  as  but  a  small  quantity  of  oil  and  dirt  are  acquired 
in  the  process  of  making  the  yarn,  thus  requiring  but  a  mild  scouring  in  the 
piece,  the  dyestuffs  employed  for  top  dyeing  often  need  not  be  specially 
fast  to  fulling — at  least  not  to  the  same  extent  as  those  required  for  the 
dyeing  of  wool  stock  or  slubbing  intended  for  woolen  yarns  which,  as  a  rule, 
are  to  be  subjected  to  heavy  scouring  or  fulling  in  the  piece.  Worsted 
mixes  are  mostly  dyed  in  the  form  of  tops,  the  mixing  being  done  in  the 
drawing  and  spinning. 

9.  Dyeing  Woolen  Yams. — The  dyeing  properties  of  yarn  are  essen- 
tially different  from  those  of  wool  stock.  In  this  respect  yarns  may  be 
divided  roughly  into  three  classes:  (1)  carpet  yarns  (and  other  low-grade 
yarns  containing  coarse,  hairy  fibers) ;  (2)  woolen  yarns  (made  in  general 
from  noils  and  clothing  wools) ;  (3)  worsted  yarns  (made  from  combed 
tops  and  including  high-grade  luster  wools).  The  first  class  of  yarns  usu- 
ally contains  a  large  amount  of  oil,  grease,  and  dirt,  and  frequently  it  is  an 
object  not  to  remove  any  more  of  these  impurities  than  possible.  The 
cheaper  acid  dyes  are  mostly  employed  and  no  special  regard  is  had  as  to 
fastness.  Woolen  yarns  are  generally  thoroughly  scoured  previous  to 
dyeing,  and  as  these  yarns  generally  go  into  goods  requiring  fulling,  the 
faster  acid  and  the  mordant  dyes  are  employed;  also  some  substantive 
dyes  are  available.  For  delicate  shades  the  yarn  must  be  bleached,  though 
in  some  cases  the  bleaching  is  done  after  the  dyeing.  Worsted  yarns  con- 
tain but  little  oil  and  dirt  (those  spun  by  the  French  system  contain  no  oil 
at  all)  and  hence  require  very  mild  scouring.  Colors  that  are  fast  to  light 
and  scouring  are  usually  required  on  worsted  yarns,  as  these  go  into  cloths 


DYEING  PIECE-GOODS  191 

that  are  not  heavily  fulled.     In  the  dyeing  of  worsted  yarns  one  desidera- 
tum is  to  avoid  felting  of  the  fibers  and  to  retain  the  luster  of  the  wool. 

10.  Dyeing  of  Piece-Goods. — Piece-goods  are  dyed  only  where  solid 
colors  are  used,  though  various  processes  have  of  late  been  introduced 
for  the  purpose  of  obtaining  varied  colored  effect  threads  in  the  body 
color  of  the  piece.  This  is  done  by  preparing  the  dyed  yarn  (usually  wors- 
ted) with  a  "  resist  "  which  prevents  this  yarn  from  taking  the  color  when 
the  piece  is  dyed.  Cloth  (especially  that  from  woolen  yarns)  requires  a 
fairly  good  scouring,  as  a  rule,  before  dyeing  in  order  to  remove  the  oil, 
dirt,  and  dressing  used  in  the  preparation  of  the  warp.  In  any  case  all 
piece-goods  should  be  thoroughly  wetted-out  with  hot  water  before  entering 
the  dyebath,  otherwise  uneven  and  cloudy  colors  are  liable  to  follow. 
Frequently  in  piece-goods  one  class  of  wool  is  used  in  the  warp  and  a  dif- 


FiG.  133. — Automatic  Dryer  for  Cotton,  Wool,  Raw  Stock,  etc. 
(Philadelphia  Textile  Machinery  Co.) 

ferent  class  of  fiber  in  the  filling;  as  different  qualities  of  wool  are  liable  to 
take  the  same  dyestuff  a  little  differently  a  "  skittery  "  effect  is  liable  to 
occur.  To  avoid  this  as  far  as  possible  the  piece  should  be  boiled  in  water 
for  some  time  before  dyeing.  Piece-goods  are  frequently  carbonized  before 
dyeing,  the  operation  being  carried  out  in  about  the  same  manner  as 
described  for  loose  wool.  In  case  the  pieces  contain  dyed  yarns  and  the 
carbonizing  is  done  previous  to  finishing,  it  is  well  to  employ  a  solution  of 
aluminium  chloride  of  9  to  12°  Tw.  in  place  of  sulphuric  acid,  as  this  will 
cause  less  injury  to  the  dyed  colors.*     A  solution  of  magnesium  chloride  of 

*  In  order  to  preserve  the  proper  dyeing  qualities  of  the  cloth  in  carbonizing  it  should 
be  borne  in  mind  that  when  wool  is  saturated  with  acid  and  exposed  to  the  light  the 
fiber  may  become  so  changed  as  to  resist  the  dyestuff.  Also  no  soap  should  be  allowed 
to  come  in  contact  with  the  carbonized  wool  until  the  fiber  has  been  thoroughly  neutral- 
ized with  soda  ash,  as  otherwise  the  soap  will  be  decomposed  by  the  acid  into  free  fatty 
acids  which  are  sticky  substances  and  very  difficult  to  remove  from  the  goods,  and 
may  cause  bad  streaks  in  the  subsequent  dyeing. 


192 


APPLICATION  OF  ACID  DYES  TO  WOOL 


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15°  Tw.  may  also  be  used.  After  saturat- 
ing with  the  sokition  the  cloth  is  hydro- 
extracted  and  dried  first  at  a  moderate 
heat  and  then  carbonized  at  a  tempera- 
ture of  about  220°  F.  The  decomposed 
vegetable  particles  are  then  mechanically 
disintegrated  and  removed  by  running 
the  pieces  for  a  short  time  in  a  drj-- 
fulling  mill,  after  which  the  goods  are 
neutralized  by  rinsing  in  a  bath  of  dilute 
•  soda  ash  or  ammonia.  Where  the  pieces 
contain  cotton  selvedges,  in  order  to  pre- 
vent the  destruction  of  the  cotton  yarns 
in  the  carbonizing  the  selvedges  should 
be  coated  with  a  solution  of  sodium  sili- 
cate (15°  Tw.)  before  entering  the  diying 
chamber.  A  thickened  soda  ash  solution 
may  also  be  used.  For  the  dyeing  of  deli- 
cate shades  or  for  very  bright  colors,  it  is 
usually  necessary  to  bleach  woolen  or 
worsted  piece-goods  previous  to  dyeing. 
This  is  generally  done  by  the  method  using 
a  solution  of  sodium  bisulphite.  The  class 
of  colors  employed  in  dyeing  piece-goods 
will  vary  according  to  the  special  demands 
of  fastness.  Acid  colors  are  mostlj-  em- 
ployed, for  piece-goods  are  scoured  and 
fulled  previous  to  dyeing,  hence,  as  a  rule, 
colors  especially  fast  to  these  requirements 
are  not  needed.  Where  colors  veiy  fast 
to  light  are  required,  the  mordant  dyes 
are  generally  used.  In  the  dyeing  of  piece- 
goods  "  Hsts,"  or  lengthwise  streaks,  are 
liable  to  develop.  This  fault  may  arise 
from  a  variety  of  causes.  In  the  first 
place,  the  goods  may  be  imperfectly 
washed,  leaving  some  of  the  color  solution 
in  the  fiber.  If  the  pieces  are  then  rolled 
up  and  stood  on  end  the  residual  color 
solution  will  drain  down  to  the  lower 
edge  and  often  result  "n  a  dark  shading 
on  that  side  of  the  goods.  If  the  rolls  of 
cloth  are  laid  flat  the  exposed  edges  will 


i:::pekimental  studies  193 

dry  out,  and  then  by  capillary  action  the  licjiior  will  be  drawn  to  the  drier 
parts  and  thus  deposit  its  color  along  both  edges,  leaving  the  center  of  the 
piece  lighter.  Lists  may  also  be  the  result  of  using  hard  water  in 
washing  after  scouring  and  before  dyeing,  and  thus  leaving  a  deposit 
of  lime  salts  either  on  one  or  both  edges  of  the  cloth,  as  above  described. 
This  will  often  cause  heavier  shades  in  the  subsequent  dyeing. 

11.  Experimental.  Exp.  50.  General  Method  of  Dyeing  on  Wool. — Prepare  a  dyebath 
containing  300  cc.  of  water,  20  per  cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and 

1  per  cent  of  Acid  Magenta.  Have  the  temperature  of  the  bath  at  about  140°  F.  and 
place  in  it  a  well-scoured  and  wet-out  test  skein  of  woolen  yarn;  by  means  of  the  stirring 
rods  give  the  skein  a  few  turns  in  the  liquor  so  as  to  saturate  the  fiber  thoroughly  with 
the  solution.  Then  allow  the  skein  to  hang  from  a  stirring  rod  into  the  dyebath,  and 
heat  the  latter  gradually  to  the  boiling  point,  turning  the  skein  from  time  to  time  so 
that  it  may  dye  up  evenly.  Do  not  maintain  the  liquor  in  a  state  of  actual  ebullition, 
as  this  will  rapidly  cause  the  fibers  of  the  wool  to  felt  together;  keep  the  bath  just  at  a 
simmer.  Continue  the  dyeing  at  this  temperature  for  one-half  hour,  turning  the  skein 
from  time  to  time.  Then  remove  the  skein,  squeeze  out  the  dye  liquor,  rinse  well  in 
fresh  water  until  no  more  color  is  removed  from  the  fiber,  then  squeeze  out  and  dry. 
This  experiment  represents  the  general  method  of  dyeing  nearly  all  acid  dyes  on  wool. 

Exp.  51.  Showing  the  Use  of  Glaubersalt  m  the  Dyebath. — Prepare  a  bath  contain- 
ing 300  cc.  of  water,  4  per  cent  of  sulphuric  acid,  and  2  per  cent  of  Naphthyl  Blue  Black. 
Dye  a  test  skein  of  woolen  yarn  in  this  bath,  entering  at  120°  F.  and  gradually  raising 
to  the  boil,  and  continue  at  that  temperature  for  one-half  hour;  then  wash  and  dry. 
It  will  be  found  that  the  skein  has  become  colored  rather  unevenly,  due  to  the  fact  that 
no  retarding  agent  such  as  glaubersalt  has  been  added.  Now  prepare  a  second  bath 
similar  to  the  preceding  one,  but  also  add  20  per  cent  of  glaubersalt,  and  then  dye  a 
second  skein  of  woolen  yarn  as  before.  After  washing  and  drying,  compare  the  even- 
ness of  the  colors  on  the  two  skeins. 

Exp.  52.  Showing  the  Influence  of  the  Amount  of  Acid  in  Dyeing  with  Acid  Colors. — 
Prepare  four  dyebaths,  each  containing  300  cc.  of  water,  20  per  cent  of  glaubersalt,  and 

2  per  cent  of  Formyl  Violet  10  B.  To  the  first  bath  add  1  per  .;ent  of  sulphuric  acid, 
to  the  second  add  2  per  cent  of  the  acid,  to  the  third  add  4  per  cent  of  the  acid,  and 
finally  to  the  fourth  add  8  per  cent  of  the  acid.  Dye  a  skein  of  woolen  yarn  in  each 
of  these  baths  in  the  usual  manner;  that  is,  entering  at  120°  F.,  gradually  raising  to  the 
boil  and  dyeing  at  that  temperature  for  one-half  hour.  After  dyeing,  wash  and  dry, 
and  compare  the  color  on  the  several  skeins.  Also  compare  the  depth  of  color  left  in 
the  respective  dyebaths  after  the  dyeing  operation  has  been  completed. 

Exp.  53.  Showing  the  Exhaustion  of  the  Dyebath. — Prepare  a  bath  containing  300 
cc.  of  water,  2  per  cent  of  Acid  Magenta,  4  per  cent  of  sulphuric  acid,  and  20  per  cent 
of  glaubersalt.  Dye  a  skein  of  woolen  yarn  in  this  bath  in  the  usual  manner.  Squeeze 
the  excess  of  dye  liquor  back  into  the  bath;  wash  the  dyed  skein  and  dry.  Then  dye 
a  second  skein  of  woolen  yarn  in  the  same  bath  without  any  further  addition  of  dyestuf? 
or  chemicals,  but  fill  up  the  dyebath  with  water  so  that  the  volume  is  brought  back  to 
the  original  point.  After  dyeing,  squeeze  the  excess  of  liquor  into  the  bath  again,  wash 
the  second  skein  and  dry.  Then  add  water  again  to  the  bath  to  bring  it  back  to  the 
original  volume,  and  dye  a  third  skein  of  woolen  yarn  in  the  same  manner,  and  after 
dyeing,  wash  and  dry.  Compare  the  color  obtained  on  the  three  skeins,  and  this  will 
give  a  good  idea  of  the  relative  exhaustion  of  the  dyebath. 

Exp.  54.  Dyeing  Acid  Dyes  in  a  Neutral  Bath. — Some  of  the  acid  dyes  are  disso- 
ciated considerably  on  dissolving  in  water  and  liberate  sufficient   color-acid   to  allow 


194 


APPLICATION  OF  ACID  DYES  TO  WOOL 


of  the  dyeing  of  the  wool  without  the  addition  of  any  acid  to  the  bath.  Prepare  a  bath 
containing  300  cc.  of  water,  10  per  cent  of  glaubersalt,  and  1  per  cent  of  Orange  EXZ. 
D\'e  a  skein  of  woolen  yarn  in  this  bath  in  the  usual  manner,  and  wash  and  dry.  Pre- 
pare a  second  bath  containing  300  cc.  of  water,  10  per  cent  of  glaubersalt,  1  per  cent  of 
Orange  ENZ,  and  4  per  cent  of  sulphuric  acid.  Dye  a  skein  of  woolen  yarn  in  this 
bath  in  the  usual  manner,  and  wash  and  dry.  Compare  the  color  obtained  on  the  two 
skeins  by  these  methods. 

Exp.  55.  Dyeing  of  Alkali  Blue. — The  color -acids  of  a  few  of  the  acid  dyes  are  insol- 
uble in  water,  and  therefore  acid  cannot  be  added  directly  to  the  dyebath,  but  must  be 
emplojed  in  a  separate  bath.  This  method  is  represented  in  the  application  of  Alkali 
Blue.  Dj-e  a  test  skein  of  woolen  yarn  in  a  bath  of  300  cc.  of  water,  10  per  cent  of  glau- 
bersalt, 1  per  cent  of  Alkali  Blue,  and  2  per  cent  of  borax.  After  boiling  for  twenty 
minutes,  remove  the  skein,  squeeze,  rinse  slightly,  and  pass  into  a  fresh  bath  contain- 


FiG.  135. — Printing  Machine  for  Slubbing.     (Vigoureux  System.) 


ing  300  cc.  of  water  and  5  per  cent  of  sulphuric  acid;  enter  at  160°  F.,  bring  to  the  boil 
and  continue  for  twenty  minutes.  Notice  that  the  full  blue  color  of  the  dj'e  is  not 
developed  until  the  material  is  treated  with  the  acid  bath.  Borax  is  a  mild  alkali,  and 
is  added  to  the  dyebath  for  the  purpose  of  insuring  its  remaining  perfectly  neutral. 
In  place  of  borax,  other  alkalies  may  be  used,  such  as  1  per  cent  of  sal  soda,  or  2  per  cent 
of  ammonia  water,  or  5  per  cent  of  sodium  silicate.  To  show  the  effect  of  adding  the 
acid  directl}'  to  the  dyebath.  prepare  a  bath  containing  300  cc.  of  water,  10  per  cent  of 
glaubersalt,  1  per  cent  of  Alkali  Blue,  and  4  per  cent  of  sulphuric  acid.  Dve  a  skein  of 
woolen  yarn  in  this  bath  in  the  usual  manner,  and  wash  and  dry.  Compare  the  result 
with  that  obtained  in  the  first  method.  Also  notice  that  the  addition  of  the  acid  to 
the  bath  causes  the  precipitation  of  the  coloring  matter.  The  color  obtained  with 
Alkali  Blue  may  be  brightened  and  at  the  same  time  rendered  faster  to  fulling,  by  the 
addition  of  a  small  percentage  of  Victoria  Blue  B  to  the  acid  developing  bath. 

Exp.  56.     Dyeing  Acid  Dyes  on  Acidified  "Wool. — Wool  combines  with  acids  with 
considerable  affinity,  and  when  so  treated  will  dye  with  the  acid  colors  without  any 


EXPERIMENTAL  STUDIES  195 

further  addition  of  acid  to  the  dyebath.  Carbonized  shoddy  (recoverod  wool  fiber 
treated  with  acid  for  the  purpose  of  decomposing  vegetable  fibers),  on  this  account,  will 
generally  dye  more  heavily  than  ordinary  wool  under  the  same  conditions.  Work  a 
test  skein  of  woolen  yarn  in  a  bath  containing  300  cc.  of  water  and  10  per  cent  of  sul- 
phuric acid,  boiling  for  fifteen  minutes.  Then  rinse  in  fresh  water  and  squeeze.  Dye 
this  skein,  together  with  one  of  ordinary  wool,  in  a  bath  containing  300  cc.  of  water,  20 
per  cent  of  glaubersalt,  and  1  per  cent  of  Formyl  Violet  10  B.  After  dyeing  wash  well 
and  dry.  Then  compare  the  two  skeins  for  depth  of  color,  and  it  will  be  found  that 
the  one  treated  with  acid  has  been  dyed  much  the  deeper  shade. 

Exp.  57.  Use  of  Acetic  Acid  in  Dyeing  Acid  Colors. — Some  of  the  acid  dyes  tend  to 
go  on  to  the  fiber  too  rapidly  if  sulphuric  acid  is  used  in  the  bath,  owing  to  the  fact  that 
the  color-acid  is  liberated  too  rapidly  and  has  a  strong  affinity  for  the  fiber;  hence  uneven 
dyeings  are  liable  to  result.  This  fault  may  be  avoided  by  using  a  weak  acid,  such  as 
acetic  acid,  and  not  adding  all  of  the  acid  at  once  but  in  several  portions.  To  more 
thoroughly  exhaust  the  bath  some  sulphuric  acid  may  be  added  towards  the  end  of  the 
dyeing  operation.*  Prepare  a  dyebath  containing  300  cc.  of  water,  20  per  cent  of 
glaubersalt,  and  1  per  cent  Sulphon  Cyanine  Blue,  and  dye  a  skein  of  woolen  yarn  as 
usual  for  twenty  minutes,  then  lift  the  skein  and  add  2  per  cent  of  acetic  acid,  and 
continue  the  dyeing  for  ten  minutes.  Lift  the  skein  a  second  time  and  add  2  per  cent 
of  sulphuric  acid  and  continue  dyeing  for  fifteen  minutes.     Then  wash  and  dry. 

Exp.  58.  Use  of  Phthalein  Dyes. — These  dyes  are  represented  by  the  eosins  and 
related  coloring  matters.  They  are  applied  in  neutral  or  weakly  acid  baths,  and  give 
delicate  red  and  pink  shades  which  are  characterized  by  a  peculiar  brightness  and 
fluorescence.  The  shades  may  also  be  made  more  brilliant  by  dyeing  on  wool  which 
has  first  been  treated  with  alum.  Prepare  a  bath  containing  300  cc.  of  water,  10  per 
cent  of  glaubersalt,  and  1  per  cent  of  Eosin,  and  dye  a  skein  of  woolen  yarn  in  the  usual 

*  There  is  a  special  group  of  acid  azo  dyes  known  as  the  Sulphon  colors  which  are 
principally  used  for  the  dyeing  of  wool  and  which  are  applied  in  neutral  of  slightly  alkaline 
baths.  They  form  sort  of  a  connecting  link  between  the  substantive  dyes  on  the  one  hand 
and  the  acid  dyes  on  the  other,  and  are  quite  useful  in  the  dyeing  of  mi.xed  wool  and 
cotton  materials  where  substantive  dyes  are  used,  as  they  may  be  employed  for  shading 
the  wool  in  the  same  neutral  bath.  They  are  mostly  blue  dyes  and  when  dyed  alone  on 
wool  they  give  shades  that  are  quite  fast  to  light,  washing  and  even  moderate  fulling. 
In  this  case  the  Sulphon  dyes  are  usually  applied  in  a  bath  containing  3  to  5  per  cent 
of  ammonium  acetate  and  10  per  cent  of  glaubersalt;  the  goods  are  entered  in  the 
lukewarm  bath,  the  temperature  is  gradually  raised  to  the  boil  and  kept  at  that  point 
for  one  hour.  Better  exhaustion  is  usually  obtained  by  adding  a  small  quantity  of 
acetic  acid  towards  the  end  of  the  dyeing.  In  using  these  colors  it  is  important  that 
the  bath  does  not  become  alkaline,  otherwise  bad  results  will  be  obtained.  This  is 
liable  to  happen  in  dyeing  carbonized  pieces  which  have  been  neutralized  with  alkali; 
such  goods  should  be  well  acidulated  before  dyeing,  otherwise  the  color  will  rush  on 
too  quickly.  In  order  to  increase  the  fastness  of  some  of  the  Sulphon  blues  the  dyeings 
may  be  after-treated  with  ^  per  cent  of  chrome  and  ^  per  cent  bluestone.  In  this  class 
of  colors  is  included  the  Sulphon  and  Lanacyl  dyes  and  such  dyes  as  Pegu  Brown  and 
Toledo  Blue.  When  dyeing  with  the  Sulphoncyanines  (also  known  as  Cooniassie  Navy 
Blue)  it  is  very  important  that  the  wool  should  be  free  from  grease  and  soapy  residues, 
as  these  colors  are  especially  sensitive  in  this  respect.  They  are  sensitive  to  reducing 
agents  yielding  brown  reduction  products,  and  this  reduction  may  take  place  in  the 
dyebath  in  the  presence  of  iron.  To  prevent  this  effect  it  is  always  advisable  to  add 
about  ^  per  cent  of  chrome  to  the  bath,  which  prevents  the  reduction  and  has  no  effect 
on  the  dyestuffs. 


196  APPLICATION  OF  ACID  DYES  TO  WOOL 

manner.  Prepare  a  second  bath  containing  300  cc.  of  water,  10  pvr  cent  of  glaubersalt, 
5  per  cent  of  acetic  acid,  and  1  per  cent  of  Eosin,  and  dye  a  skein  of  woolen  j-arn  in  the 
usual  manner.  Prepare  a  third  bath  containing  300  cc.  of  water,  5  p.-r  cent  of  alum  and 
5  per  cent  of  tartar,  and  5  per  cent  of  acetic  acid;  boil  a  skein  of  woolen  yarn  in  this  bath 
for  one-half  hour,  then  lift  and  add  1  per  cent  of  Eosin,  and  continue  dyeing  for  twenty 
minutes.  Erythrosine,  Phlo.xine,  and  Rose  Bengale  also  belong  to  this  group  of  phthalein 
dyes.     The  tartar  is  used  in  the  bath  to  aid  in  the  decomposition  of  the  alum. 


CHAPTER  VII 
APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

1.  Dyeing  of  Silk  with  Acid  Colors. — The  three  methods  outHned  under 
the  experiments  of  this  chapter  describe  briefly  the  general  reactions  of  acid 
dyes  with  silk.  In  practice  boiled-off  liquor  (or  bast  soap,  as  it  is  also  called) 
is  nearly  always  employed  with  the  acid  colors.*  For  the  dyeing  of  10  lbs. 
of  silk  skems  a  dyebath  is  prepared  with  about  40  gallons  of  water  and 
10  to  15  gallons  of  boiled-off  liquor.  For  most  purposes  the  bath  is  acidi- 
fied with  an  excess  of  sulphuric  acid;  that  is  to  say,  sufficient  sulphuric  acid 
is  added  to  give  a  decidedly  acid  taste  to  the  liquor.  The  acidity  may 
also  be  tested  with  blue  litmus  paper,  which  should  be  turned  red.  Before 
the  addition  of  the  dyestuff  the  bath  is  heated  to  100°  F.,  any  scum  which 
may  have  formed  is  removed  with  a  ladle,  and  then  the  silk  is  entered 
and  given  several  turns.  The  skeins  are  then  thrown  up  and  the  dyestufif 
solution  added.  The  temperature  is  raised  to  140°  F.,  the  silk  re-entered 
and  the  dyeing  continued  to  the  boil.  Each  time  the  bath  is  heated  the 
goods  should  be  thrown  up  to  avoid  tangling.  When  the  addition  of  sul- 
phuric acid  is  not  considered  desirable,  acetic,  formic,  tartaric,  or  citric 
acid  may  be  employed. 

A  too-prolonged  boiling  of  the  bath  should  be  avoided,  as  this  is  liable 
to  damage  the  silk  and  dull  the  luster.  When  possible  to  obtain  level 
shades  it  is  advisable  to  keep  the  bath  under  the  boiling  point,  f     In 

*  Though  the  practice  of  using  bast  soap  in  silk  dyeing  is  almost  universal,  the 
absolute  necessity  of  its  employment  has  been  questioned.  Ganswindt  (Theorie  und 
Praxis  der  vwdernen  Fdrherei,  2d  part,  page  16)  claims  to  have  shown  by  practical 
tests  that  the  results  obtained  without  the  use  of  bast  soap  are  equally  as  good  as  those 
obtained  otherwise,  the  luster  and  feel  of  the  fiber  being  the  same.  Though  the  pres- 
ence of  the  bast  soap  in  the  bath  retards  the  velocity  of  the  dyeing  (which  aids  the  pen- 
etration and  evenness  of  the  color),  it  also  prevents  a  good  exhaustion  of  the  dyestuff, 
which  is  a  drawback. 

+  In  all  cases  of  dyeing  silk  which  is  not  twisted  (or  corded)  it  is  advised  to  keep  the 
dye  liquor  under  the  point  of  ebullition.  This  will  prevent  the  fine  silk  fiber  from 
becoming  frayed  and  tangled.  The  influence  of  the  temperature  on  the  affinity  of  many 
dyestuffs  for  silk  is  also  very  marked;  in  many  cases  the  dyestuff  is  taken  up  better 
by  the  fiber  when  the  temperature  is  considerably  under  the  boiling  point,  and  may 
even  be  considerably  stripped  at  the  more  elevated  temperature.  Some  dyers  con- 
sider it  best  to  use  temperatures  between  140  and  180°  F.,  the  exact  temperature  being 
dependent  on  the  dyestuff  employed. 

197 


198 


APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON.  ETC. 


dyeing  silk  with  the  eosin  dyestuffs  an  excess  of  acid  should  be  avoided,  just 
sufficient  being  added  to  give  the  bath  a  slightly  acid  taste,  or  so  that  the 
liquor  no  longer  gives  a  froth.  In  this  case  the  bath  is  spoken  of  as 
"  broken,"  and  is  practically  neutral  in  reaction,  as  it  should  affect  neither 
blue  or  red  litmus  paper.* 

When  dyeing  Alkali  Blue  on  silk  an  alkaline  bath  is  employed,  the  bath 
l)eing  prepared  with  about  one-half  the  usual  quantity  of  boiled-off  liquor, 
and  no  acid  is  added.  After  dyeing  the  silk  is  rinsed  and  passed  through  a 
bath  strongly  acidified  with  acetic  acid. 


Fig.  130. — Dyeing  Machine  for  Sluhbing.     (Obcrmaie. .) 

Tiissah  silk  is  usually  dyed  without  the  addition  of  boiled-ofT  liquor,  a 
little  acetic  or  sulphuric  acid  being  added  The  boiled-off  liquor  from 
Tussah  silk  is  not  suitable  for  use  in  dyeing,  as  it  contains  too  much 
impurity. 

In  order  to  obtain  uniform  shades  in  the  dj^eing  of  silk,  it  is  frequently 


*  it  is  generally  considered  essential  to  add  the  acid  to  the  bath  first,  and  after- 
wards the  soap  solution  or  boiled-off  liquor.  This  probably  avoids  the  separation  of 
fatty  acid  which  might  be  induced  by  the  contact  of  the  stronger  acid  with  the  soap 
solution  if  the  reverse  procedure  was  followed. 


CONDITIONS   FOR   USING   ACID   DYES  199 

necessary  to  add  the  dye  solution  in  several  successive  portions  and  to  raise 
the  temperature  of  the  bath  very  slowly. 

Though  boiled-off  liquor  (or  its  equivalent  in  soap)  is  nearly  always 
used  as  an  ingredient  in  the  bath,  it  is  not  essential  to  the  actual  dyeing 
process.  Silk  may  be  dyed  with  the  acid  colors  in  practically  the  same 
manner  as  used  for  wool;  that  is  to  say,  preparing  the  dyebath  with  dye 
solution  and  acid.  The  use  of  glaubersalt  is  not  to  be  recommended  in 
silk  dyeing  as  it  appears  to  affect  the  luster  of  the  fiber.  Silk  may  be 
dyed  quite  satisfactorily  in  a  bath  with  the  addition  of  from  2  to  5  per  cent 
of  acetic  acid,  entering  the  goods  at  140°  F.,  gradually  raismg  to  200  to 
205°  F.,  and  maintainLig  at  that  temperature  for  one-half  to  one  hour. 
After  dyeing,  rinse  off  in  fresh  water  and  "  brighten  "  by  working  in  a 
very  dilute  bath  (about  1  per  cent)  of  acetic  or  tartaric  acid;  squeeze  well 
and  dry  without  rinsing.  This  process  of  so-called  "  brightening  "  is  for 
the  purpose  of  increasing  the  luster  and  giving  a  "  scroop  "  to  the  fiber.* 
The  drying  of  the  small  amount  of  the  organic  acid  into  the  fiber  appears 
to  give  this  result  without  injury  to  the  material. 

In  its  relation  to  acid  dyes,  silk  differs  somewhat  from  wool  in  that  the 
dye  appears  to  be  taken  up  better  at  a  temperature  somewhat  under  the 
boil.  This  difference  is  made  use  of  in  the  dyeing  of  wool  and  silk  mixed 
goods  by  employing  a  boiling  bath  with  the  addition  of  a  relatively  small 
amount  (2  per  cent)  of  acetic  acid;  under  these  conditions  the  color  will  feed 
almost  exclusively  onto  the  wool.  The  silk  may  be  dyed  subsequently  in  an- 
other shade  if  desirable  by  using  a  fresh  lukewarm  bath  with  the  proper  dye. 

As  previously  mentioned,  silk  does  not  exhibit  the  same  affinity  as  wool 
for  the  acid  dyes,  and  as  a  consequence,  they  show  less  fastness  to  washing 
on  silk.  Some  of  the  acid  colors,  in  fact,  are  removed  from  silk  by  washing 
in  plain  water.  This  must  not  be  taken,  however,  as  a  general  rule,  as 
there  are  quite  a  number  of  acid  dyes  which  produce  colors  on  silk  of  very 
satisfactory  fastness  to  washing.  The  fastness  to  light  and  other  con- 
ditions is  generally  about  the  same  on  silk  as  on  wool. 

The  use  of  boiled-off  liquor  or  "  bast  "  soap  in  the  dyeing  of  silk  has 
perhaps  several  functions:  (a)  it  acts  as  a  regulator  in  the  dyeing  process, 
retarding  the  absorption  of  the  color  and  giving  more  regular  and  better 
penetrated  dyeings;  (b)  it  prevents  loss  of  weight  in  the  silk,  especially  if 
there  is  much  silk-glue  still  left  on  the  fiber;  (c)  it  adds  to  the  softness  and 
luster  of  the  dyed  silk. 

In  the  dyeing  of  spun  silk  it  is  not  so  customary  to  use  the  boiled-off 
liquor,  the  yarns  being  dyed  simply  in  the  ordinaiy  acid  bath.  Spun  silk 
should  also  be  "  brightened  "  with  acetic  or  tartaric  acid. 

*  In  the  case  of  dyeing  light  shades  where  the  dyebath  is  practically  exhausted, 
instead  of  using  a  separate  "  brightening  "  bath,  the  goods  coming  from  the  dyebath 
may  simply  be  wrung  out  and  dried  without  washing. 


200         APPLICATION  OF  ACID  BYES  TO  SILK,  COTTON,  ETC. 

The  fastness  of  the  acid  dyeings  on  silk  may  be  somewhat  increased  by 
an  after-treatment  with  tannin  or  by  an  after-treatment  with  almninium 
acetate. 

The  acid  dyes  are  principally  used  on  silk  for  the  production  of  fancy 
colors,  the  black  acid  dyes,  though  largely  used  on  wool,  have  but  httle 
use  on  silk,  as  it  is  not  possible  to  produce  as  satisfactoiy  a  black  with  them 
as  with  Logwood.  The  black  acid  dyes  do  not  seem  to  properly  fill  the 
fiber  so  as  to  make  it  opaque  to  light,  in  consequence  of  which  the  color 
exhibits  a  slaty  appearance,  while  with  Logwood  (by  reason  of  the  rela- 
tively large  amount  of  pigment  mordant  employed)  the  fiber  is  rendered 
opaque  and  the  color  produced  is  a  full  rich  black.  Furthermore,  by  dj-eing 
with  LogM'ood  and  suitable  mordants,  a  considerable  amount  of  weighting 
ma}'  be  added  to  the  silk. 

2.  Notes  on  the  Weighting  of  Silk. — In  the  boiling-off  of  silk  when  all  of 
the  silk  gum  is  removed  there  is  a  loss  in  weight  of  about  22  to  25  per  cent; 
that  is  to  say  1  lb.  of  raw  silk  will  yield  onl}-  about  12  ozs.  of  boiled-off  silk. 
In  order  to  make  up  for  this  loss  the  dyer  is  usually  required  to  weight 
the  silk  with  suitable  materials  so  as  to  bring  the  weight  of  the  dj-ed  product 
back  to  the  original  weight  of  the  raw  silk.  This  is  called  the  "  par  " 
weight,  and  the  silk  is  not  considered  as  really  weighted  at  all.  But  very 
frequently  a  great  deal  more  weighting  material  is  added  than  that  neces- 
sary' to  bring  it  back  to  par,  and  the  weighting  may  run  as  high  as  50  to  100 
per  cent,  and  even  at  times  to  as  much  as  300  per  cent.  In  par  silk  the 
actual  amount  of  weighting  for  12  ozs.  of  real  silk  is  4  ozs.,  so  as  to  bring 
it  back  to  16  ozs.  or  1  lb.  If  the  dyer  is  required  to  weight  the  silk  50  per 
cent  above  par,  it  is  intended  that  for  1  lb.  of  raw  silk  he  receives  he  should 
deliver  1^  lbs.  of  dj'ed  silk;  but  as  1  lb.  of  raw  silk  represents  only  12  ozs 
of  actual  silk,  and  as  this  is  brought  up  to  24  ozs.  there  is  actually  added  12 
ozs.  of  weighting  material,  or  an  amount  equal  in  weight  to  that  of  the  silk 
itself.  Silk  weighted  to  this  extent  is  known  as  24  oz.  silk.  The  custom- 
aiy  weighting  of  silk  for  ordinary  purposes  is  from  24  to  28  ozs.,  and  by 
this  is  meant  that  1  lb.  of  raw  silk  is  brought  up  to  this  weight  by  the  dyer. 

There  are  two  general  methods  of  weighting  silk,  (a)  for  blacks,  and 
(6)  for  white  or  fancy  colors.  When  weighting  is  done  for  black  dyed  silk 
the  materials  employed  are  tannins  and  iron  salts.  The  silk  is  nearly 
always  weighted  in  the  form  of  skein  yarns  as  this  is  the  most  suitable  form 
with  which  to  operate.  The  boiled-off  silk  is  steeped  in  a  rather  strong 
bath  of  cutch,  gambler,  or  other  suitable  tannin.  As  the  silk  fiber  is  par- 
ticularly reactive  towards  solutions  of  tannin,  it  readily  absorbs  the  tannic 
acid  from  solution,  and  the  silk  becomes  charged  with  a  considerable 
proportion  of  tannin.  The  skeins  are  then  squeezed  and  passed  into  a 
bath  containing  nitrate  of  iron  (which  is  really  a  basic  sulphate  of  iron, 
and  so  called  by  reason  of  it  being  made  by  the  action  of  nitric  acid  on  fer- 


METHODS   OF   WEIGHTING  SILK 


201 


rous  sulphate).  This  precipitates  tannate  of  iron  in  the  fiber,  which  is  of  a 
dark  gray  or  black  color.  A  treatment  with  yellow  prussiate  of  potash 
is  also  given  so  as  to  furnish  a  precipitate  of  Prussian  Blue.  This  gives  a 
pleasing  bluish  tone  to  the  finished  black  and  also  adds  to  the  weighting. 
A  treatment  with  a  weak  alkaline  bath  or  soap  is  also  given  in  order  to 
complete  the  precipitation  and  fixation  of  the  iron  compounds  and  to  neu- 
tralize any  excess  of  tannic  acid.  These  treatments  are  repeated  several 
times,  depending  on  the  degree  of  weighting  desired;  usually  each  treat- 
ment adds  from  12  to  20  per  cent  of  weight.  After  the  weighting  processes 
have  been  completed,  the  silk  is  dyed  with  Logwood,  to  which  is  added 
some  Fustic  (for  the  purpose  of  obtaining  an  intense  jet  black) .     Black 


V/Z/Z/AVf 


Fig.  137. — Card  Sliver  Bleaching  Machine.     (Pornitz.) 


silks  are  usually  weighted  more  heavily  than  fancy  colored  silk,  and  36  to 
40  oz.  silk  is  often  produced  by  the  dyer. 

When  the  weighting  is  for  silk  that  is  to  be  left  white  or  is  to  be  dyed  in 
fancy  colors,  naturally  the  tannin  and  iron  method  cannot  be  used  on 
account  of  the  dark  color  of  the  weighting  material.  In  order  to  obtain  a 
weighting  which  gives  practically  no  color  to  the  silk  it  is  customary  to  use 
stannic  chloride.  The  silk  has  a  strong  affinity  for  this  compound  and 
takes  up  the  tin  quite  readily,  and  the  latter  is  fixed  in  the  fiber  by  washing 
in  water  containing  lime.  The  silk  skeins  are  treated  with  a  stannic 
chloride  (SnCU)  solution  of  about  50°  Tw.  cold.  For  this  purpose  the 
silk  is  packed  in  a  rubber-lined  hydro-extractor  and  the  tin  solution  (known 
in  the  dyehouse  as  "  dynamite  ")  is  run  in.  The  liquor  is  forced  through 
the  fiber  very  evenly  by  the  rapid  motion  of  the  hydro-extractor  and  at 
the  same  time  the  excess  of  liquor  is  removed.     The  silk  is  then  well  washed 


202  APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

in  water  containing  some  lime  in  solution.  Or  it  may  be  washed  with  a 
dilute  solution  of  sodium  phosphate.  This  causes  the  fixation  of  the  tin 
in  the  fiber  as  a  stannic  hydrate  (or  as  a  basic  phosphate).  Care  must  be 
taken  to  conduct  the  tin  treatment  at  a  low  temperature  (about  40  to 
50°  F.)  which  is  usually  accomplished  by  having  the  tin  treatment  carried 
out  in  a  suitable  room  provided  with  artificial  refrigeration,  so  that  a  con- 
stant low  temperature  may  be  maintained  irrespective  of  the  atmospheric 
temperature.  It  is  also  necessar>^  to  remove  thoroughlj'  all  of  the  acid 
radical  (the  hydrochloric  acid)  from  the  tin  combined  with  the  silk.  The 
tin  chloride  on  treatment  with  water  is  decomposed  into  tin  hydrate  and 
hydrochloric  acid.  The  latter  is  washed  out  and  is  further  neutralized  by 
the  lime  or  sodium  phosphate  that  is  used  with  the  water.  If  any  residues 
of  the  acid  are  left  in  the  silk  the  fiber  will  develop  tenderness  and  gratlually 
become  rotten,  or  show  so-called  "  burnt  "  places.  By  conducting  the 
operations  with  proper  care  and  by  maintaining  constant  conditions  it  has 
been  demonstrated  that  tin-weighted  silk  is  not  weakened  and  does  not 
show  any  degree  of  deterioration  even  over  long  periods  of  time.  One  tin 
treatment  usually  adds  from  20  to  25  per  cent  of  weight,  and  higher  weight- 
ing may  be  obtained  Iw  repeating  the  treatments  several  times.  Silk 
weighted  in  this  manner  with  tin  may  be  dyed  delicate  light  shades  or  may 
be  left  as  a  white  fiber.  For  the  latter  purpose  a  bleached  silk  will  have  to 
be  used.  The  tin  weighting  does  not  interfere  with  the  subsequent  dyeing 
operations ;  in  fact  the  tin  acts  as  a  mordant  for  manj'-  of  the  dyes  and  gives 
faster  colors  than  would  otherwise  be  the  case.*  The  tin  weightmg  also 
adds  to  the  luster  of  the  silk  as  well  as  to  the  body  of  the  fiber;  it  also 
gives  it  a  good  firm  feel  and  allows  of  a  high  degree  of  "  scroop  "  being 
imparted  to  the  silk. 

3.  Dyeing  Cotton  with  the  Acid  Dyes. — The  acid  dyes  have  little  or  no 
direct  attraction  for  cotton  or  vegetable  fibers  in  general  and  on  this 
account  they  have  a  veiy  limited  use  in  this  field  of  dyeing.  There  are 
cases,  however,  where  the  acid  dyes  are  used  on  cotton,  and  among  them 
may  be  noted  dj'eings  for  upholsteiy  and  drapery  fabrics  or  such  materials 
that  require  colors  having  fastness  to  light  but  no  especial  requirements 
as  to  fastness  to  washing. f  As  cotton  is  very  inert  chemically,  and  as  it  is 
presumed  that  the  attraction  of  the  animal  fibers  for  the  acid  dyes  is  due 
to  the  basic  properties  of  these  fibers,  it  would  be  reasonable  to  expect 

*  When  dyeing  acid  colors  on  tin-weighted  silk  difficulty  may  at  times  be  experienced 
in  obtaining  even  shades  owing  to  uneven  or  defective  weighting.  Also  some  acid 
dj'es  have  a  much  lessened  affinity  for  weighted  silk,  the  tin  salt  acting  as  a  resist  to  the 
dye. 

t  The  Croceine  Scarlets  and  other  such  azo  compounds  obtained  from  beta-naphthol 
sulphonic  acid  B,  gamma  acid,  or  alpha-naphthol  disuljihonic  acid  Sch,  are  used  consid- 
erably for  this  class  of  dyeing,  as  the  colors  have  a  greater  fastness  to  light  than  the  ben- 
zidine dyee,  and  furthermore  are  not  sensitive  to  acids. 


DYEING  COTTON  WITH  ACID  COLORS  203 

that  if  cotton  were  mordanted  with  a  basic  mordant  it  would  then  be 
capable  of  being  dyed  with  the  acid  colors.*  We  find  this,  in  fact,  to  be  the 
case.  If  the  cotton  material  is  mordanted  with  suitable  metallic  oxides 
(bases),  it  will  combine  with  the  acid  dyes.  Alum  is  the  principal  metallic 
base  used  in  this  connection,  chiefly  on  account  of  the  fact  that  the  salt  is 
readily  dissociated  in  such  a  manner  as  to  liberate  the  acid  (sulphuric  acid) 
and  precipitate  the  base  (alumina,  AI2O3),  within  the  fiber.  Unlike  wool, 
cotton  exhibits  very  little  chemical  activity  towards  solutions  of  metallic 
salts,  and  therefore  only  a  few  of  the  more  readily  dissociated  salts  (such 
as  alum)  are  available  for  use  in  the  direct  mordanting  of  cotton.  Alum 
is  also  suited  to  this  purpose  by  reason  of  the  colorless  quality  of  the  base, 
so  that  the  color  of  the  resulting  dyeing  is  not  affected. 

In  a  few  cases  the  acid  dyes  are  used  on  cotton  without  a  mordant, 
simply  using  the  dye  solution  itself  for  impregnating  the  fiber.  In  such  a 
method  of  dyeing,  it  is  necessary  to  use  as  short  a  bath  as  possible,  and 
common  salt  is  added  until  the  bath  stands  at  5  to  7°  Tw.  The  dyeing  is 
done  in  a  hot  solution  (160  to  180°  F.)  and  the  goods  are  simply  wrung 
out  and  dried  without  washing.  Only  pale  shades  may  be  dyed  in  this 
manner,  and  the  colors,  of  course  have  no  fastness  to  washing,  nor  are 
they  as  fast  to  light  as  those  produced  with  a  metallic  mordant. 

The  usual  procedure  in  dyeing  the  acid  colors  on  cotton  is  to  make  up 
the  dyebath  with  the  required  dye  solution  and  the  least  amount  of  water 
as  possible;  alum  (10  to  20  per  cent)  and  either  glaubersalt  or  common  salt 
(20  per  cent)  is  also  added.  The  goods  are  dyed  at  about  180°  F.  for  an 
hour,  squeezed  or  wrung  out  as  evenly  as  possible,  and  then  dried  without 
rinsing.  As  the  dyebath  exhausts  but  poorly  it  should  be  used  as  a  stand- 
ing kettle  for  the  dyeing  of  succeeding  lots  of  goods,  j 

*  It  has  been  suggested  to  "  animalize  "  the  cotton  by  coating  it  with  gelatine 
or  albumin.  Experiments  have  been  made  by  first  treating  the  cotton  with  tannic  acid 
and  then  with  a  solution  of  gelatine,  the  latter  combining  with  the  tannin  to  form  an 
insoluble  compound.  Also  treating  the  cotton  with  a  solution  of  albumin  and  steaming 
has  been  suggested.  The  albumin  or  gelatine  mordant  thus  obtained  will  dye  with  the 
acid  colors.  None  of  these  processes,  however,  has  any  practical  value.  If  cotton  is 
treated  for  several  hours  with  strong  nitric  acid  it  also  shows  an  affinity  for  acid  colors; 
but  here  the  fiber  is  probably  changed  to  a  nitrated  body. 

t  The  following  recommended  processes  are  also  representative  of  this  method: 

(1)  Enter  the  previously  soaped  cotton  material  in  the  dyebath  containing  the  acid 
color  and  3  to  4  per  cent  of  alum,  and  dye  lukewarm  (Bayer) . 

(2)  Dye  in  as  short  a  liquor  as  possible  containing  the  dyestufT  together  with  43 
ozs.  of  alum  and  2  lbs.  of  glaubersalt  per  10  gallons  of  liquor.  The  quantity  of  dyestuff 
is  dependent  on  the  depth  of  shade  required;  the  first  bath  should  be  charged  with 
considerably  larger  quantities  of  dyes  than  the  subsequent  baths,  for  example, 

First  bath.    Subspquont  bath. 

For  dark  shades 10%  2%  dve 

For  light  shades 3%  0.5%" dye 

Enter  the  cotton  at  120  to  140°  F.  and  without  further  heating  dye  in  the  cooling  bath. 
Then  squeeze  out  and  dry  without  rinsing  (Cassella) . 


204 


APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 


Depending  on  circumstances  and  the  character  of  the  tlyestuff  employed 
this  method  may  be  varied  in  several  ways.     The  cotton  may  be  first 


Fig.  138.— Dyeing  Machine  for  Sliver.     (Mather  &  Piatt.) 


impregnated  with  a  solution  of  soap  containing  also  a  small  amount  of 
gelatine;    the  goods  are  squeezed  out  and  then  entered  in  the  dyebath 


MORDANT   FOR  ACID   DYES  205 

which  is  made  up  with  10  per  cent  of  akim  and  20  to  40  per  cent  of  common 
salt.  In  another  method  the  cotton  is  first  mordanted  with  a  basic  solu- 
tion of  alum  prepared  by  dissolving  1  lb.  of  alum  and  ^  lb.  of  soda  ash  in 
20  gallons  of  water.  The  goods  are  worked  in  this  bath  hot  for  a  short 
time  and  then  laid  down  in  the  liquor  and  steeped  for  four  to  five  hours. 
Squeeze  and  dye  in  a  separate  dyebath  at  160°  F.  A  method  by  which 
colors  faster  to  washing  may  be  obtained  is  to  first  treat  the  cotton  with 
tannin  and  then  mordant  with  alum.  The  tannin  is  rather  easily  taken  up 
by  the  cotton  and  seems  to  fix  the  alum  mordant  by  forming  an  insoluble 
tannate  of  aluminium.  Enter  the  cotton  in  a  boiling  bath  containing  4  per 
cent  of  tannic  acid;  work  the  material  for  a  short  time  and  then  steep  in  the 
cooling  bath  for  two  hours.  Squeeze,  and  pass  through  the  mordant  bath  of 
alum  and  soda  ash  prepared  as  above,  rinse  slightly  and  then  dye  as  usual. 

A  tin  mordant  may  also  be  used  on  cotton,  as  this  gives  a  colorless  base 
for  combination  with  the  acid  colors.  The  goods  are  steeped  at  140°  F. 
in  a  bath  containing  |  lb.  of  stannate  of  soda  to  20  gallons  of  water;  squeeze 
and  steep  for  two  hours  in  the  alum  bath  prepared  as  above,  then  after- 
wards dye  as  usual.  The  tin  mordant  may  also  be  used  by  first  steeping 
the  goods  in  a  soap-gelatine  bath  (10  per  cent  of  soap  and  5  per  cent  of 
gelatine)  at  140°  F.,  then  treating  for  one-half  hour  in  a  cold  bath  con- 
taining 10  per  cent  of  stannic  chloride  (SnCU) ;  squeeze,  treat  with  the 
basic  alum  bath,  and  then  dye  as  usual.* 

In  cases  where  the  dyestuff  used  forms  insoluble  precipitates  with  alum 
(Biebrich  Scarlet,  Fast  Red  A,  etc.),  it  is  advisable  to  give  the  alum-mor- 
danted cotton  a  slight  rinsing  before  entering  the  dyebath,  otherwise  the 
dyeings  may  be  streaky  and  will  crock  badly.  A  small  quantity  of  acetic 
acid  should  also  be  added  to  the  dyebath. 

The  rather  special  group  of  acid  dyes  including  Water  Blue  (Soluble 
Blue)  and  the  water-soluble  indulines  and  nigrosines  is  sometimes  used  in 
cotton  dyeing.  They  may  be  either  dyed  direct  by  the  alum  and  glauber- 
salt  method  or  on  a  tannin-antimony  mordant  as  described  in  the  applica- 
tion of  basic  dyes.  Very  bright  shades  of  blue  may  be  obtained  in  this 
way  which  have  good  fastness  to  light  but  little  or  no  fastness  to  washing. 
Soluble  Blue  is  also  used  as  a  tinting  blue  in  the  bleaching  and  laundering 
of  cotton  goods. 

*  Modifications  of  this  process  are  as  follows: 

(1)  Allow  the  previously  boiled-off  cotton  material  to  lie  for  two  hours  (or  better 
yet,  overnight)  in  a  bath  containing  sodium  stannate  at  6  to  7°  Tw.;  wring  out  and  pass 
through  a  bath  containing  15  to  20  per  cent  of  alum  (or  7  to  10  per  cent  of  aluminium 
sulphate)  and  2  to  3  per  cent  of  soda.  After  a  couple  of  hours  wring  out  or  rinse,  and 
dye  lukewarm  (Bayer). 

(2)  Treat  the  cotton  for  one  hour  in  a  solution  of  stannic  chloride  7  to  10°  Tw., 
wring  out  and  pass  through  a  bath  containing  aluminium  acetate  6°  Tw.  for  one  to  two 
hours.     Then  rinse  and  dye  in  a  lukewarm  bath  (Bayer). 


206 


APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 


The  eosin  group  of  acid  dj'es  is  also  used  to  a  limited  extent  in  cotton 
dj'eing  for  the  production  of  bright  and  delicate  print  colors.  These  dyes 
are  applied  in  as  short  a  bath  as  possible  with  the  addition  of  30  to  GO  per 
cent  of  common  salt;  run  for  three-fourths  hour  at  100°  F.,  then  wring 
out  and  diy  without  rinsing.  A  starting  bath  will  require  2  to  10 
per  cent  of  dyestuff,  as  the  exhaustion  is  very  poor;  but  subsequent 
dyeings  in  the  standing  bath  will  need  only  the  addition  of  about  one-fifth 
this  amount  of  dye.  A  better  quality  of  bright  pink  shades  with  these 
dyes  may  be  obtained  b}-  using  a  mordant  of  Turkey-red  oil.  This  method 
is  usually  applied  to  yarn  in  the  following  manner :  the  skeins  are  steeped 
in  lots  of  1  lb  each  in  a  liquor  consisting  of  one  part  of  Turkey-red  oil 
and  two  parts  of  water.     The  yarn    must  be    evenly  impregnated  and 


Fig.  139. — Skein  Dyeing  Machine.     (Dehaitre.) 


squeezed  (this  is  usually  done  in  a  special  apparatus),  and  then  dried. 
Generally  the  mordanting  operation  is  repeated  several  times.  The 
yarn  is  then  dyed  in  a  short  cold  bath  with  the  addition  of  a  little  acetic 
acid.  This  method  gives  a  bright  fluorescent  pink  on  bleached  cotton  that 
can  be  ol)taincd  in  no  other  manner. 

4.  The  After-chromed  Acid  Dyes. — X  number  of  the  acid  dyes  may  be 
after-treated  with  solutions  of  metallic  salts,  either  for  the  purpose  of 
developing  them  or  of  making  the  dyed  color  faster  to  light  and  washing. 
Chrome  is  the  chief  salt  used  for  this  purpose,  though  bluestone  is  some- 
times used  also.*     The  action  of  the  chrome  on  these  dyes  may  be  in  two 

*  An  example  of  the  use  of  bluestone  is  in  the  dyeing  of  Naphthylamine  Black ;  in 
this  case  the  dyebath  is  charged  with  1  per  cent  of  oxalic  acid,  .5  per  cent  of  acetic  acid, 
10  per  cent  of  glaubersalt  and  the  required  amount  of  dye.  After  dyeing  for  one  hour 
at  the  boil,  add  3  per  cent  of  bluestone  and  continue  for  one-half  hour. 


USE  OF  AFTER-CHROMED   DYES  207 

ways  (a)  to  oxidize  or  otherwise  develop  the  color,  as  with  the  chromotrop 
dyes  and  Azo  Rubine;  in  which  case  the  chroming  generally  alters  the 
shade  of  the  dyed  color  very  considerably,  as  for  example  from  a  red  to  a 
black;  (6)  to  form  a  color-lake  with  the  acid  dye  after  the  manner  of  the 
mordant  dyes.  The  latter  class  really  falls  under  the  mordant  colors,  for 
in  the  practical  application  of  these  dyes,  the  acid-dyed  color  is  not  used, 
but  the  operation  is  always  carried  on  to  the  after-chroming  before  the 
dyeing  is  considered  finished.  Representative  dyes  of  this  class  are 
Diamond  Black,  Chrome  Black,  Cloth  Red,  Anthracene  Brown  and 
Alizarine  Yellow  GG.  It  is  always  a  doubtful  question  whether  to  consider 
these  dyes  under  the  division  of  acid  colors  or  under  the  mordant  dyes.  As 
they  are  all  azo  dyes,  however,  and  as  they  are  dyed  in  acid  baths  and  give 
more  or  less  satisfactory  colors  even  when  considered  solely  as  acid  dyes 
without  a  subsequent  chroming,  it  may  perhaps  be  proper  to  treat  them 
under  the  consideration  of  acid  dyes. 

But,  on  the  other  hand,  the  useful  colors  which  they  furnish  are  only 
those  which  are  obtained  by  using  a  true  mordant  to  form  an  actual 
color-lake,  and  on  this  account  they  should  be  regarded  as  mordant 
dyes  in  the  true  sense.  The  methods  of  dyeing  also  tend  to  have  these 
dyes  considered  under  the  group  of  mordant  colors,  therefore  a  dis- 
cussion of  their  use  will  be  postponed  until  the  group  of  mordant  dyes 
is  considered. 

The  chromotrop  dyes  are  so-called  because  they  are  obtained  from 
chromotropic  acid  combined  with  various  diazo  bases.  They  are  almost 
exclusively  used  in  wool  dyeing.  The  colors  produced  by  direct  dyeing  in 
an  acid  bath  are  mostly  reds  and  bluish  reds,  and  though  these  colors  may 
be  used  as  such,  they  are  not  of  much  importance  owing  to  their  lack  of 
fastness  and  due  to  the  fact  that  the  same  colors  may  be  obtained  by 
the  use  of  cheaper  dyes.  By  after-treating  with  chrome,  however,  dark 
blue  to  bluish  black  colors  are  obtained  which  have  a  high  degree  of  fast- 
ness and  are  very  desirable  colors.  The  dyeing  is  carried  out  in  the  usual 
manner  in  a  bath  containing  10  to  20  per  cent  of  glaubersalt  and  4  per  cent 
of  sulphuric  acid,  and  boiling  for  one  hour.  After  dyeing,  the  goods 
are  lifted  out,  the  dye  liquor  cooled  off  somewhat,  and  1|  to  2  per  cent 
of  chrome  and  1  per  cent  of  sulphuric  acid  are  added,  the  goods  are 
re-entered  and  color  developed  by  boiling  for  one  hour.  The  colors  thus 
obtained  are  very  fast  to  light,  washing,  acids,  alkalies,  and  moderately 
fast  to  fulling.  The  fastness  to  fulling  is  said  to  be  improved  by  adding 
3  per  cent  of  lactic  acid  with  the  chrome. 

5.  On  the  Proper  Storage  of  Dyestuffs. — Dyestuffs  should  be  kept  in  a 
cool  dry  room,  and  any  barrels  or  tins  which  have  been  opened  should  be 
kept  well  covered  up,  otherwise  one  color  may  become  contaminated  by 
dust  from  another  dye;  also  the  dyestuffs  are  liable  to  absorb  moisture  from 


208 


APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 


the  air.  The  absorption  of  moisture  may  cause  the  dyestuff  to  cake 
together  and  become  difficult  to  dissolve,  antl  besides  the  dyestuff  will 
alter  its  weight  b}^  the  amount  of  moisture  absorljed.  Steam  from  the 
dyehouse  should  be  carefully  excluded  from  the  drug  room  in  which  the 
dyes  are  stored.  Dyestuffs  in  the  form  of  pastes  should  always  be  well 
stirred  up  before  weighing  out  and  should  be  kept  from  exposure  to  the  air, 
otherwise  the  water  of  the  paste  will  evaporate  and  the  dyestuff  will  alter 
veiy  materially  in  its  strength.  Paste  dyes  are  usually  of  20  per  cent 
strength;  that  is,  they  contain  20  per  cent  of  actual  dyestuff,  the  rest 
being  water. 


Fig.  140. — Skein  Dyeing  Machine.     (Zittauer.) 


Paste  dyes  in  barrels  should  be  protected  with  a  suitable  tightly  fitting 
cover  on  the  inside  of  which  is  a  dampened  cotton  cloth.  This  will  tend 
to  prevent  the  evaporation  of  moisture  from  the  paste  and  thus  preserve 
its  normal  strength.  Paste  colors  should  also  be  preserved  from  freezing, 
as  this  may  cause  alteration  in  the  properties  and  strength  of  the  dj'estuff. 
Dyestuffs  should  never  be  stored  or  weighed  off  in  the  dyehouse  proper 
or  in  any  place  where  the  goods  to  be  d3^ed  are  directly  exposed,  as  dust 
from  the  colors  may  cause  mj-sterious  spots  on  the  goods. 

6.  Dissolving  of  Dyestuffs. — The  proper  solution  of  dyestuffs  is 
an  important  factor  in  obtaining  good  results  in  dyeing,  both  with 
respect  to  the  testing  of  dyes  and  in  their  practical  application  on  a  large 
scale.  The  solubility  of  dyes  varies  considerably  depending  on  the  nature 
of  the  particular  dye,  but  even  for  the  most  difficultly  soluble  dyes  about 


DISSOLVING  DYESTUFFS  209 

200  to  250  parts  of  water  are  generally  ample  to  effect  a  good  solution; 
and  in  cases  where  the  dye  is  readily  soluble,  from  10  to  50  parts  of  water  is 
sufficient.*  The  solubility  of  the  dye  also  depends  on  the  kind  of  water 
used ;  pure  soft  water  should  always  be  used  wherever  possible,  and  if  hard 
water  alone  is  available  it  should  be  corrected  by  the  addition  of  a  small 
amount  of  acetic  acid  (about  f  oz.  of  acid  of  9°  Tw.  to  100  gallons  of  water 
for  each  10°  of  hardness  in  parts  per  million)  sufficient  to  give  the  water  a 
sUght  acid  reaction  with  litmus  paper. 

Dyestuffs  should  always  be  well  dissolved  before  adding  to  the  dye- 
bath,  and  in  most  cases  the  solution  should  be  strained  through  a  fine  sieve 
or  cloth  in  order  to  remove  insoluble  matters  or  undissolved  specks  of 
dyestuff.  Generally  speaking  boiling  water  is  used  for  dissolving  dyes, 
though  there  are  certain  cases  where  a  lower  temperature  should  be  used. 
In  the  case  of  many  basic  dyes,  such  as  Methyl  Violet,  Malachite  Green, 
etc.,  it  is  best  to  first  stir  up  the  dyestuff  with  a  little  cold  water  to  which  a 
small  amount  of  acetic  acid  has  been  added,  and  then  dissolve  in  boiling 
water,  f 

In  dissolving  colors  in  the  dyehouse,  it  is  often  the  practice  to  put  the 
dyestuff  in  a  wooden  bucket,  pour  cold  water  over  it  and  then  boil  up  by 
introducing  steam  through  an  open  pipe.  Under  these  circumstances  it 
frequently  happens  that  the  live  steam  of  a  high  temperature  coming  in 
direct  contact  with  the  dry  dyestuff  will  cause  decomposition,  leading 
in  some  cases  to  the  formation  of  highly  insoluble  sticky,  tarry  products 
which  may  cause  considerable  trouble  in  dyeing.  The  proper  procedure 
should  be  to  mix  the  proper  amount  of  boiling  hot  water  with  the  dye- 
stuff  and  dissolve  with  good  stirring. 

Some  of  the  acid  dyes  J  are  better  dissolved  by  the  addition  of  a  little 
sulphuric  acid  to  the  water;  but  in  dissolving  Alkali  Blue  or  Water  Blue, 
a  small  quantity  of  soda  ash  or  borax  should  be  added,  especially  if  the 
water  used  is  at  all  hard.      For  the  phthalein  dyes  like  Eosin,  Rose  Ben- 

*  In  general  it  may  be  said  that  for  difficultly  soluble  dyes  ^  lb.  may  be  dissolved  in 
10  gallons  of  water,  and  for  ordinary  dyes  about  2  lbs.  may  be  dissolved  in  10  gallons  of 
water. 

t  A  few  colors  like  Auramine  should  not  be  dissolved  in  boiling  water,  as  the  color 
is  partially  decomposed;  such  colors  should  be  dissolved  at  about  160  to  180°  F. 

I  The  acid  dyes,  as  a  rule,  are  quite  soluble  in  water,  and  can  usually  be  dissolved 
in  about  twenty-five  to  fifty  times  their  weight  of  water.  With  acid  dyes  the  use  of 
hard  water  is  not  so  injurious,  as  sulphuric  acid  is  added  to  the  bath  and  this  will  effect- 
ively prevent  the  formation  of  any  insoluble  lime-lake  of  the  coloring  matter.  The 
acid  dyes  may  be  dissolved  in  boiling  water  without  danger  of  being  decomposed  at  that 
temperature.  In  general  it  may  be  said  that  the  more  sulphonic  acid  groups  present 
in  the  acid  dyestuff,  the  more  soluble  it  will  be.  The  acid  dyes  may  be  dissolved  in 
copper  or  tinned  copper  vessels  but  in  this  case  no  addition  of  acid  should  be  made 
while  dissolving,  as  many  of  these  dyes  are  reduced  by  stannous  salts,  such  as  would 
be  formed  by  contact  of  the  acidified  solution  with  the  tin. 


210  APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

gale,  etc.,  the  water  should  first  be  boiled  up  with  a  little  soda  ash,  and 
after  settling  the  clear  liquor  should  be  used  for  dissolving  the  dye. 

In  dissolving  substantive  dyes  the  water  should  be  made  slightly 
alkaline  with  a  little  soda  ash.  The  sulphur  dyes  are  quite  insoluble  in 
water  and  require  to  be  dissolved  in  a  solution  of  sodium  sulphide  or  caustic 
soda.  Generally  the  amount  of  sodium  sulphide  required  is  equal  to  that 
of  the  ch'estuff,  though  in  the  case  of  higiily  concentrated  dyes  (sulphur 
blacks)  twice  the  quantity  of  sodium  sulphide  ma}^  be  necessaiy. 

In  the  use  of  standing  baths  it  may  at  times  be  found  that  the  dye- 
stuff  becomes  partially  precipitated.  This  may  be  caused  by  impurities 
in  the  water  or  by  impurities  introduced  In'  the  materials  being  dyed,  such 
as  soapy  residues,  pectin  matters  of  cotton,  etc.  Or  the  precipitation  may 
be  due  to  the  gradual  accumulation  of  too  much  salt  in  the  bath.  It  may 
be  dangerous  to  use  such  old  baths  for  further  d\'eing,  as  the  colors  so 
obtained  maj^  show  lack  of  fastness  to  rubljing  or  washing  and  defective 
and  spotted  goods  may  result. 

Some  d^'es  require  special  precautions  and  methods  for  solution,  and 
attention  will  be  called  to  these  when  such  dyes  are  under  consideration. 

It  is  a  bad  policy  to  dissolve  the  coloring  matter  du'ectly  in  the  dj^evat 
itself,  as  undissolved  parts  maj-  adhere  to  the  pipes  or  sides  of  the  vat,  or 
portions  of  the  d3'estuff  may  be  decomposed  by  contact  with  the  live  steam 
or  the  superheated  pipe.  An  enameled  pail  is  an  excellent  vessel  for  the 
dissolving  of  d3'estuffs.  If  a  wooden  Ijucket  is  used,  the  wood  will  absorb 
a  considerable  quantity  of  the  concentrated  dye  solution,  and  unless  it  is 
used  continually  for  the  same  dyestuff,  succeeding  solutions  will  be  shaded 
and  discolored  b}^  the  bleeding  out  of  the  preceding  color.  Frequently 
the  exhausted  liquor  of  a  preceding  dyebath  is  emploj-ed  for  dissolving  a 
fresh  amount  of  dyestuff.  This,  however,  may  sometimes  lead  to  bad 
results  owing  to  the  acid  character  of  the  liquor  or  to  the  presence  of  salts, 
so  when  this  method  is  used  it  should  be  ascertained  if  the  dyestuff 
employed  is  injured  by  such  a  treatment. 

In  certain  cases  stock  solution  of  dyestuffs  are  prepared  of  definite 
strengths,  and  the  d3'-er  uses  these  by  measuring  off  certain  volumes  from 
time  to  time  as  required.  These  stock  solutions  should  be  of  sufficient 
dilution  to  insure  the  complete  solution  of  the  dyestuff  emploj-ed.  It 
should  also  be  borne  in  mind  that  a  number  of  dyestuffs,  though  perfectly 
dissolved  in  a  hot  solution,  will  crystallize  out  on  cooling,  and  furthermore 
many  dye  solutions  deteriorate  on  prolonged  standing,  hence  a  reasonable 
degree  of  caution  must  be  exercised  in  the  preparation  and  maintenance 
of  stock  solutions. 

7.  Action  of  Metals  on  Dyestuff  Solutions. — Dyevats  and  apparatus 
are  gcncrall}-  made  of  wood,  but  there  are  forms  of  dyeing  machinery 
employing  metal  in  contact  with  the  dyebath.     This  is  frequently  copper 


DYEING  APPARATUS 


211 


or  bronze,  and  there  are  certain  dyes  which  are  quite  sensitive  to  these 
metals.  Usually  the  action  of  copper  in  this  connection  may  be  prevented 
by  hanging  a  piece  of  zinc  in  the  bath,  or  l)y  the  addition  of  a  little  ammo- 
nium sulphocj^anide.  Sulphur  dyes,  being  dissolvcnl  with  sodium  sulphide, 
cannot  be  used  in  contact  with  copper,  brass,  or  bionze  metal,  so  wood  or 
iron  dj'e  vessels  must  be  used.  In  some  forms  of  dyeing  machines  (such  as 
cop  machines  where  perforated  spindles  are  used)  the  metal  parts  are  made 
of  nickel  or  monel  metal. 

8.  Apparatus  for  Dyeing. — Yarn  is  mostly  dyed  in  suitable  wooden 
vats,  the  skeins  being  suspended  in  the  vats  from  wooden  sticks.*     Many 


Fig.  141. — Skein  Dyeing  Machine;  Revolving  Type. 

Machine  Co.) 


(Klauder-Weldon  Dyeing 


dyes  are  more  or  less  sensitive  to  the  action  of  metals,  though  in  many 
cases  bronze  or  copper  surfaces  may  be  in  contact  with  the  dyevat  without 
injury  to  the  color.  Silk  is  frequently  dyed  in  copper  vats.f  The  sensi- 
tiveness of  most  dyes  to  copper  may  be  avoided  by  the  placing  of  strips 

*  These  sticks  are  generally  of  birch,  maple,  or  fir  when  used  for  wool  or  cotton. 
\Yhen  silk  skeins  are  dyed,  however,  it  is  better  to  use  sticks  of  polished  willow,  though 
bamboo  sticks  are  also  excellent. 

t  On  account  of  the  fineness  of  the  silk  fiber  and  its  liability  to  become  frayed  and 
broken  by  rubbing  against  the  sides  of  wooden  vats,  it  is  customary  to  employ  copper 
vats.  It  is  possible  to  use  wooden  vats,  however,  for  both  boiling-off"  and  dyeing  silk 
if  they  are  lined  on  the  inside  with  canvas;  this  will  present  a  smooth  surface  to  the  silk 
fiber  and  prevent  it  being  frayed  by  catching  in  the  fine  splinters  always  present  in  the 
wooden  vats. 


212  APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

of  zinc  in  the  vat  or  by  the  addition  of  ammonium  sulphocyanide.  Yarn 
may  also  be  dyed  on  machines,  where  the  hanks  are  turned  mechanically. 
Loose  wool  is  frequently  dyed  by  poling  in  large  round  copper  vats;  it 
may  also  be  (tyed  in  rotating  machines,  doth  is  generally  dyed  in  vats, 
being  turned  by  means  of  a  revolving  winch;  or  it  may  be  dyed  on  a  jigger, 
consisting  of  two  sets  of  rollers  which  roll  the  cloth  on  and  off  through  the 
dye  liquor.  Warps  are  also  dyed  by  machine.  Yarn  may  also  be  dj-ed  in 
cops  by  means  of  suitable  machines  so  devised  as  to  force  the  dye  liquor 
through  the  cop  by  pressure  or  suction. 

9.  Apparatus  for  Dyeing  Cotton  Yam. — Wooden  vats  are  generally 
used  for  dyeing  cotton  in  the  form  of  hanks,  and  they  are  usually  constructed 
to  hold  50  or  100  lbs.  It  is  seldom  they  are  made  larger  or  smaller  than 
this  for  practical  work.  During  the  dyeing  process  the  hanks  are  hung  on 
smooth  rods,  so  that  only  about  one-fourth  of  their  length  is  above  the  dye 
liquor.  The  yarn  is  turned  by  hand,  or  a  stick  may  be  used,  in  which  case 
a  pointed  stick  which  is  thinner  than  that  on  which  the  yarn  hangs,  is 
passed  through  the  hank  below  the  other  stick,  and  the  yarn  is  then  raised 
with  it  and  turned.  The  vats  must  be  so  constructed  that  the  yarn  can 
be  easily  turned  without  too  much  water  l^eing  required  in  proportion  to 
the  cotton.     The  following  are  suitable  internal  dimensions: 

r  length,  64  ins. 
For  50  lbs.  yarn      \   breadth,  22^  ins, 
I  depth,  23 i  ins. 

r  longtli,  118  ins. 
For  100  lbs.  yarn        breadth,  22.1  ins. 
i  depth,  23^  ins. 

The  dye  liquor  is  heated  by  a  steam  coil  which  may  enter  the  liquor  at 
the  top  end  of  the  vat.  If  the  vats  are  long,  two  coils  may  be  used,  one 
from  each  end,  but  if  short,  one  coil  will  be  sufficient.  These  coils  are 
closed  at  the  ends,  but  the  sides  are  suitably  perforated  with  small  holes, 
and  it  is  best  to  fix  them  on  to  the  steam  pipe  with  a  union  joint  so  they 
may  be  removed  from  the  vat  if  necessary.  The  steam  coil  should  lie 
under  a  perforated  false  bottom  of  wood,  so  as  to  prevent  the  yarn  from 
coming  in  direct  contact  with  the  hot  pipe,  and  also  so  that  the  force  of  the 
escaping  steam  may  be  broken  and  disseminated  and  not  tangle  up  the 
yarn.  In  some  cases,  the  pipe  is  fitted  behind  a  perforated  wooden  par- 
tition which  stands  4  to  6  ins.  from  the  top  end  of  the  vat,  and  which  is  a 
little  lower  than  the  latter.  This  arrangement  offers  certain  advantages,  as 
solutions  of  dyestuffs,  etc,  may  be  poured  into  the  space  behind  it  during 
the  dyeing  process  and  gradually  distributed  through  the  liquor  without 
having  to  remove  the  yarn.  To  let  the  liquor  run  off  after  dyeing,  it  is 
best  to  have  the  vat  fitted  with  a  valve  which  can  be  opened  by  turning 


APPARATUS   FOR   DYEING    YARN  213 

a  handle  from  the  outside.  The  old  method  of  having  a  plug  to  be  drawn  is 
bad,  as  the  workmen  are  liable  to  be  scalded.  The  rods  on  which  the  yarn 
is  hung  should  be  hard  straight  sticks  of  hazel,  ash,  etc.,  from  which  all 
knots  are  removed  so  that  no  rough  places  are  left. 

Besides  the  vat  method  of  dyeing,  cotton  yarn  may  be  dyed  by  machines ; 
in  one  form  a  vat  is  used  as  with  hand  dyeing,  but  the  sticks  are  turned 
mechanically  by  a  system  of  interacting  cogs.  In  another  form,  such  as  the 
Klauder-Weldon  or  Giles  machine,  the  rods  are  arranged  on  a  circular  spider 
frame  rotating  in  a  semicircular  vat,  the  sticks  also  being  turned  mechan- 
ically as  the  frame  rotates;  in  this  method,  only  one-half  the  load  of  yarn 
is  in  the  liquor  at  any  one  time,  so  that  economy  in  the  amount  of  dye 
liquor  is  effected;  the  yarn  is  also  kept  out  straight  by  being  more  or 
less  stretched  between  the  rods,  which  prevents  tanghng. 

Another  method  of  machine  dyeing,  which  has  come  into  practice  of 
late,  and  which  may  also  be  employed  for  yarns,  though  it  is  mostly  used 
for  cops,  bobbins,  etc.,  is  where  the  material  is  tightly  packed  in  a  chamber 
of  metal  fixed  to  a  suction  tube  and  pmiip;  the  cotton  remains  stationaiy 
and  the  dyeing  is  effected  by  forcing  the  heated  liquor  through  the  material. 

Cotton  yarn  is  also  largely  dyed  in  the  form  of  prepared  warps,  in 
which  case  a  special  warp-dyeing  machine  is  used,  the  warp  or  chain  run- 
ning over  rollers  up  and  down  through  the  vat  several  times,  then  through 
squeeze  rollers;  if  necessary  several  runs  are  made  through  the  machine 
to  obtain  the  desired  shade.  In  the  latter  case,  the  machine  may  consist  of 
several  compartments  each  provided  with  squeeze  rollers,  and  the  yarn  is 
run  through  each  compartment  sue  cessively. 

10.  Apparatus  for  Dyeing  Woolen  Yarn. — This  material  is  usually  dyed 
in  wooden  vats  similar  to  those  just  described  for  the  dyeing  of  cotton  yarn. 
It  must  be  borne  in  mind,  however,  that  for  woolen  yarn  dyed  on  sticks  in 
large  vats  there  will  be  required  about  300  to  450  gallons  of  water  for  100 
lbs.  of  yarn,  depending  on  the  nature  of  the  material.  In  general  the  yarn 
is  entered  into  the  hot  acid  dye  liquor  (in  the  case  of  acid  dyes)  and  is  dyed 
for  one  and  one-half  to  two  hours  at  the  boil.  About  2  to  3^  lbs.  of  yarn 
are  placed. on  each  stick,  and  for  a  100-lb.  lot  four  men  are  generally  em- 
ployed in  turning  at  the  beginning,  but  later  only  two  men  are  required. 
The  yarn  must  not  be  turned  more  often  than  is  necessary  to  obtain  even 
colors,  otherwise  the  fibers  will  become  felted.  From  time  to  time  the  posi- 
tion of  the  sticks  should  be  changed,  that  is,  those  in  the  middle  of  the  vat 
should  be  moved  to  the  ends,  and  so  on.  On  a  first  kettle  when  dyeing 
woolen  yarn  it  is  usual  to  add  a  rather  large  quai:  ity  of  glaubersalt,  often 
as  much  as  50  lbs.  on  a  100-lb.  vat,  this  being  a  great  help  toward  the  pro- 
duction of  level  dyeings.  On  subsequent  dyeings  in  the  same  vat  only  5  lbs. 
of  glaubersalt  need  be  added.  As  a  rule,  old  dye  liquors  cannot  be  used  for 
longer  than  a  week;   though  there  are  exceptional  cases  where  they  may  be 


214  APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

used  continuously  for  several  months.  Usually,  the  shades  on  woolen  yarn 
are  not  perfectly  level  at  the  beginning  of  the  process;  but  the  color  should 
distril)uto  itself  evenly  after  being  l)oiled  for  sometime;  generally,  the  dye- 
ings should  be  perfectly  level  a  quarter  of  an  hour  after  the  color  solution 
has  been  added  to  the  bath. 

Woolen  yarn  may  also  be  dyed  in  suitable  machines  similar  to  those 
used  for  cotton  dyeing,  the  rotating  spider  form  of  machine  being  used 
extensively  in  this  country,  England,  and  Germany.  This  is  especially 
true  for  fine  worsted  yarns,  or  in  fact  any  kind  of  yarn  which  is  easily 
matted  or  tangled;  in  such  cases  it  is  almost  impossible  to  obtain  satis- 
factory results  by  dyeing  by  hand  in  open  vats  on  sticks,  as  the  motion  of 
the  yarn  and  the  boiling  of  the  bath,  especially  if  live  steam  is  used  for 
heating,  cause  a  great  felting  and  tangling  of  the  threads.  Such  j^arn  is 
best  dyed  in  a  revolving  machine,  where  the  hanks  may  be  stretched  out 
and  preserved  in  a  straight  condition  throughout  the  dyeing  operation,  and 
no  felting  will  result.  Yarn  which  is  liable  to  curl  up,  due  to  tight  twist, 
should  be  scalded  before  washing  or  dj^eing;  this  may  be  done  by  twisting 
the  hanks  together  tightly  and  laying  them  in  boiling  water  for  a  couple 
of  hours,  then  allowing  them  to  cool  before  untwisting.  In  using  the 
revolving  machine  for  dyeing  or  scouring,  this  previous  scalding  will  be 
su]:)erfluous,  as  the  yarn  will  naturally  undergo  this  operation  when  stretched 
in  the  machine  during  the  dyeing  process  itself.  With  such  yarns,  how- 
ever, the  hanks  should  not  be  unstretched  until  they  have  passed  through 
cold  water  or  have  cooled  down. 

11.  Apparatus  for  Dyeing  Silk  Yam. — Small  lots  of  silk  yarn  are  usually 
dyed  in  copper  boilers,  and  larger  lots  in  copper  or  copper-plated  vats. 
These  are  usually  mounted  on  wheeled  frames,  so  that,  with  the  exception 
of  the  long  heavy  vats,  they  maj'^  be  conveniently  moved  about  the  dj'e- 
house.  This  arrangement  is  a  desirable  one,  as  the  dyer  requires  to  use 
larger  or  smaller  vats  according  to  the  quantity  of  silk  which  has  to  be  dyed 
at  one  time.  As  the  vats  are  often  used  for  the  most  varying  shades,  it 
is  necessary  to  frequently  cleanse  them  thoroughly.  For  this  purpose 
they  may  be  first  boiled  out  with  old  boiled-off  liquor,  or  the  inner  sides 
may  be  thoroughly  scoured  with  a  hot  strong  solution  of  soda  ash.  After 
this  has  been  run  out,  the  vat  is  rinsed  with  water  and  then  cleansed  again 
with  dilute  sulphuric  acid,  and  finally  rinsed  out  again  with  water.  The 
larger  vats,  which  are  stationary,  are  generally  heated  with  a  steam  coil 
placed  under  a  perforated  false  bottom;  for  the  smaller  vats,  usually 
movable  steam  pipes  are  inserted.  These  steam  pipes  should  be  fitted  so 
as  to  turn  in  a  ball-and-socket  joint  so  that  they  may  be  moved  around  in 
any  direction.  The  silk  is  hung  in  hanks  on  smooth  rods  in  the  same  man- 
ner as  wool  or  cotton,  about  -i-  lb.  of  silk  being  distributed  on  each  stick. 
Silk  may  also  be  dyed  in  machines,  the  chief  form  in  this  country  being  the 


WATER  FOR   DYEING 


215 


revolving  spider  type,  for  which  purpose  a  special  machine  is  constructed. 
The  spider  is  so  arranged  that  at  any  time  the  entire  lot  of  yarn  may  be 
raised  out  of  the  liquor. 

12.  Influence  of  the  Water  Employed  in  Dyeing. — Water  as  employed 
in  the  dyehouse  for  the  preparation  of  vats  and  the  solution  of  the  dye- 
stuffs  and  various  chemicals  is  generally  obtained  either  from  a  river  supply 


Fig.  V-2 — Skein  Dyeing  Machine  for  Silk  with  Automatic  Hoist.     (Giles  Dye 

Machinery  Co.) 

or  from  a  well  or  spring.  Rain-water  is  sometimes  collected  and  employed 
for  purposes  where  a  very  pure  article  is  desired,  such  as  for  the  solution  of 
dyestuffs,  etc.;  it  is  usually  not  available  in  sufficient  quantities  nor  regular 
enough  in  its  supply  to  be  serviceable  for  the  preparation  of  dye  vats. 
Rain-water  is  considered  as  the  purest  form  of  natural  water.  Well  and 
spring  water  are  derived  from  rain-water  which  has  passed  through  the 
surface  of  the  earth  until  it  has  reached  an  impervious  layer  which  causes 
it  to  collect  in  subterranean  reservoirs  from  which  it  may  be  pumped  as 


216  APPLICATION  OF  ACID  DYES  TO  SILK,  COTTON,  ETC. 

well-water,  or  it  may  flow  underground  until  it  eventually  reappears  at  the 
surface  as  a  spring.  Such  water  usually  contains  various  metallic  salts  in 
solution  and  generally  has  but  little  insoluble  matter  in  suspension.  The 
exact  nature  and  amount  of  the  dissolved  sul^stances  will  naturally  vary 
considerably  with  the  character  of  the  soil  and  rock  through  which  the 
water  has  passed.  Some  rocks,  like  granite  and  gneiss,  are  verj^  insoluble, 
and  water  percolating  through  these  may  be  quite  free  from  dissolved 
impurities,  and  springs  or  wells  from  such  a  source  may  be  quite  "  soft." 
If  the  water,  however,  in  its  percolation  through  the  soil  passes  through 
strata  of  limestone,  chalk,  sandstone,  etc.,  some  mineral  compounds  pass 
into  solution,  especially  salts  of  magnesia  and  Imie.  Such  a  water  is 
termed  "  hard."  Iron  compounds  form  a  common  constituent  of  soils 
and  rocks,  and  consequently  water  that  passes  through  such  will  be  liable 
to  contamination  with  iron;  this  will  be  more  especially  the  case  if  at  the 
same  time  it  is  in  contact  with  decaying  vegetable  matter,  as  the  latter 
furnishes  certain  organic  acids  which  exert  a  strong  solvent  action  on  the 
iron  compounds.  Water  containing  a  marked  content  of  iron  is  termed 
"  chalybeate  "  or  "  ferruginous." 

River-water  consists  largely  of  surface-water,  that  is,  rain-water  which 
drains  directly  from  the  surface  of  the  soil  without  percolating  through 
the  ground  to  any  extent;  besides  this,  river-water  also  contains  well  or 
spring-water  feeding  into  it  from  small  streams,  etc.,  ha\dng  their  origin 
in  springs.  The  surface-water  draining  into  a  river  is  liable  to  bring  into  it 
a  large  amount  of  suspended  matter,  though  not  so  much  dissolved  matter. 
The  nature  and  extent  of  this  suspended  matter  will,  of  course,  vary 
largely  with  the  season  of  the  year  and  the  character  of  the  environment. 
From  this  it  may  be  seen  that  river-water  will,  as  a  rule,  contain  more 
suspended  matter  and  less  dissolved  matter  than  well-water.  The  sus- 
pended matter  is  comparatively  easily  removed,  however,  whereas  the 
dissolved  substances  may  give  rise  to  considerable  trouble. 

The  influence  of  the  impurities  in  water  on  the  dyeing  operations  will 
depend  very  largely  on  the  character  of  the  dyestuffs  employed.  Hard 
water  containing  lime  and  magnesia  compounds,  as  a  rule,  does  not  inter- 
fere with  the  dyeing  of  colors  in  an  acid  bath,  as  the  addition  of  the  acid 
prevents  any  precipitation  of  the  coloring  matter  by  the  metallic  salt.  In 
certain  cases  the  tone  of  the  resulting  color-lake  maj^  be  somewhat  modified 
by  the  presence  of  the  mineral  salts,  but  such  is  veiy  rarely  the  case. 
The  presence  of  iron,  however,  even  in  very  slight  quantities,  in  the  water, 
may  cause  a  considerable  alteration  in  the  color,  usually  dulling  and  dark- 
ening it.  With  the  general  class  of  basic  dyes  hard  water  cannot  be  em- 
ployed without  suitable  correction  by  the  addition  of  acetic  acid.  The 
basic  dyes  form  insoluble  precipitates  with  lime  and  magnesia  compounds 
which  will  result  in  a  large  loss  of  coloring  matter  and  also  faulty  and 


EFFECT   OF  HARD  WATER   IN   DYEING  217 

streaky  dyeing  by  reason  of  the  sticky  precipitate  of  coloring  matter 
becoming  smeared  on  the  material  being  dyed.  The  presence  of  iron  in  the 
water  is  also  very  deleterious  in  using  basic  dyes.  With  the  class  of  sub- 
stantive colors  the  influence  of  hard  water  varies  largely  with  the  particular 
dyestuff,  in  some  cases  causing  precipitation  and  in  others  not.  As  a  gen- 
eral rule,  however,  it  may  be  taken  that  hard  witer  is  deleterious  with  this 
class  of  dyes,  and  should  be  corrected  by  the  addition  of  a  suitable  amount 
of  soda  ash  in  order  to  precipitate  all  the  lime  and  magnesia  compounds 
which  may  be  in  solution.  The  presence  of  iron  is  also  bad,  as  it  causes  a 
discoloration  of  the  dyestuff.  With  mordant  dyes  the  use  of  hard  water, 
if  it  does  not  contain  any  iron,  is  considered  beneficial,  as  the  lime  present 
produces  a  better  color-lake;  in  fact,  unless  the  water  is  sufficiently  hard, 
a  solubl3  salt  of  lime  is  usually  added  in  the  dyeing  of  most  alizarine  colors. 
In  certain  cases  where  a  dulled  or  "  saddened  "  effect  is  desired,  the  pres- 
ence of  iron  may  be  beneficial.* 

In  mordanting  operations,  such  as  in  the  use  of  metallic  salts  on  wool 
or  silk,  hard  water  may  be  used  with  impunity  provided  it  does  not  contain 
any  iron,  which  will  result  in  the  dulling  of  the  eventual  color-lake.  In 
mordanting  cotton  with  tannic  acid,  the  use  of  hard  water  may  be  con- 
sidered as  somewhat  beneficial,  if  anything,  as  it  leads  to  a  better  fixation 
of  the  tannin  mordant. 

In  bleaching  operations  on  cotton,  where  chloride  of  lime  or  acids  or 
caustic  soda  may  be  employed,  the  use  of  hard  water  is  not  injurious; 
though  it  should  not  be  contaminated  with  iron.  In  the  bleaching  of  wool 
with  solutions  of  sodium  bisulphite,  hard  water  may  also  be  employed. 
In  all  operations  of  scouring  or  bleaching  where  soap  solutions  are  employed 
hard  water  should  not  be  used,  as  the  soap  forms  a  highly  insoluble  and 
sticky  precipitate  with  the  mineral  salts  present  in  the  water,  causing 
thereby  great  loss  of  soap  and  the  liability  of  serious  faults  in  the  textiles 
due  to  the  precipitate  of  soap  becoming  incorporated  with  the  fabrics  (see 
page  100).  One  part  of  lime  present  in  hard  water  will  precipitate  about 
sixteen  parts  of  ordinary  soap. 

*  In  the  case  of  water  having  a  considerable  degree  of  hardness  the  carbonates  of 
lime  or  magnesia  present  may  have  some  influence  in  dyeing  and  mordanting.  In  the 
case  of  mordanting,  carbonates  will  produce  precipitates  with  salts  of  iron,  aluminium 
or  tin,  and  will  reduce  bichromates  to  the  neutral  salts,  tartar  and  tannin  are  also  more 
or  less  neutralized.  In  certain  dyeing  operations  the  presence  of  carbonates  exerts  a 
considerable  influence;  with  Cochineal  Scarlets,  for  instance,  the  shades  are  much  bluer, 
the  dyes  such  as  Methyl  Violet,  Victoria  Blue,  Alizarine  Blue  and  Coerulein  are  pre- 
cipitated by  carbonates,  which  may  lead  to  loss  of  dyestuff  and  the  production  of 
streaky  colors.  In  the  case  of  Alizarine  Red  the  presence  of  lime  salts  is  vecy  bene- 
ficial, as  shown  by  Hummel  {Jour.  Soc.  Dyers  &  Col.,  18S4,  page  11).  Carbonate  of 
lime  or  magnesia,  if  present  in  considerable  amount  gives  deeper,  though  duller, 
shades  with  Logwood  and  Fustic. 


218  APPLICATION  OF  ACID  DYES  TO  SILK,   COTTON,  ETC. 


When  hard  water  is  eini)l(n-('tl  for  the  washing  of  fabrics,  whether  after 
scouring,  dyeing,  or  bleaching,  it  may  give  rise  to  certain  faults  known  as 
"  lists  "  by  reason  of  the  uneven  draining  and  evaporating  of  the  hard 
water  from  the  goods,  thus  leaving  deposited  in  the  material  the  dissolved 


W 


mineral  matter.*     Hard  water,  in  fact,  is  probably  moi-e  injurious  in  this 
connection  than  in  most  of  the  other  operations  of  dyeing. 

*  These  "  lists  "  (see  page  192)  are  light  or  dark  streaks  runniiig  lengthwise  with  the 
cloth.  When  the  washed  cloth  is  rolled  up  and  laid  horizontally,  the  water  evaporates 
at  each  end,  thus  causing  a  greater  deposition  of  mineral  matter  at  the  ends  (sides  of  the 
cloth)  t-han  at  the  middle.  If  the  roll  is  stood  on  end  the  water  seeps  down  to  one  side 
and  evaporates  slowly  depositing  more  mineral  matter  at  one  side  and  gradually  shading 


EXPERIMENTAL  STUDIES  219 

Water  employed  for  the  dyeing  of  silk  should  be  especially  pure  and 
soft.  As  soap  or  boiled-off  liquor  is  almost  a  universal  addition  to  the 
dyebath  in  the  case  of  silk,  if  the  water  is  at  all  hard  a  portion  of  the  soap 
will  be  precipitated  in  the  bath,  and  the  sticky  and  dirty  scum  will  con- 
taminate the  silk  fiber  and  injure  its  luster  and  appearance. 

13.  Experimental.  Experiment  59.  Dyeing  of  Silk  with  Acid  Dyes.— Dye  a  test 
skein  of  silk  yarn  in  a  bath  containing  150  cc.  of  water,  2  per  cent  of  sulphuric  acid,  and 
2  per  cent  Naphthol  Yellow;  enter  at  120°  F.,  gradually  raise  to  the  boil,  and  dye  at 
that  temperature  for  one-half  hour,  then  wash  well  and  "  brighten  "  by  passing  through 
a  bath  containing  1  gram  of  tartaric  acid  and  150  cc.  of  water  at  100°  F.*  Squeeze 
without  washing  and  dry.  Like  wool,  silk  will  also  combine  directly  with  the  acid  col- 
ors. Usually  a  bath  is  employed  containing  a  considerable  amount  of  boiled-off  liquor 
acidified  with  acetic  acid.  This  is  to  prevent  as  little  loss  in  the  weight  of  the  silk  as 
possible  during  the  dyeing,  as  silk  usually  comes  to  the  dyer  still  containing  more  or 
less  of  the  silk-glue,  which  would  come  off  in  the  dyebath  if  there  were  not  a  considerable 
amount  of  the  same  sul)stance  present. 

Exp.  60.  Use  of  Acetic  Acid  in  Dyeing  Silk. — Dye  a  test  skein  of  silk  yarn  in  a  bath 
containing  150  cc.  of  water,  4  per  cent  of  acetic  acid,  and  2  per  cent  Eosin;  enter  at  120° 
F.,  gradually  raise  to  the  boil,  and  dye  at  this  temperature  for  one-half  hour.  Then 
wash  well  and  brighten  as  in  Exp.  59.  Squeeze  and  dry.  This  method  of  dyeing  is 
used  where  feebly  acid  dyes  are  employed. 

Exp.  61.  Use  of  Boiled-off  Liquor  in  Dyeing  Silk. — Boiled-off  liquor  is  the  scouring 
bath  left  after  the  scouring  of  silk  with  strong  soap  solutions,  and  consi-sts  of  the  solu- 
tion of  soap  and  silk-glue.  Prepare  a  bath  containing  15  cc.  of  boiled-off  hquor  and  125 
cc.  of  water,  2  per  cent  of  Brilliant  Croceine,  and  sufficient  sulphuric  acid  to  give  the 
bath  a  decidedly  acid  reaction  with  litmus  paper.  The  presence  of  the  silk-glue  pre- 
vents the  precipitation  of  the  soap  by  the  addition  of  the  acid.  Dye  a  test  skein  of 
silk  yarn  in  this  bath,  entering  at  100°  F.  and  gradually  raising  to  180°  F.,  and  continue 
at  that  temperature  for  one-half  hour.  Wash  well  and  brighten  as  described  in  Exp.  59. 
Squeeze  and  dry. 

Exp.  62.  General  Method  of  Dyeing  Acid  Dyes  on  Cotton. — Cotton  has  no  direct 
affinity  for  the  acid  colors  and  requires  a  basic  mordant  to  combine  with  the  color-acid  of 
the  dyestuff.     Alum  is  used  at  times  for  this  purpose.     Preioare  a  bath  containing 

off  to  the  other  side.  On  dyeing,  the  mineral  matter  may  act  as  a  resist  or  as  a  mordant, 
depending  on  the  dye  employed,  thus  giving  white  lists  or  dark  lists  as  the  case  may  be 
(see  also  page  193) . 

*  The  purpose  of  this  treatment  is  to  brighten  the  dyed  color  and  also  to  impart 
to  the  silk  fiber  a  "  scroop,"  causing  it  to  emit  a  crunching  or  crackling  sound  when 
squeezed  and  rubbed.  The  cause  of  the  brightening  action  on  the  color  is  probably  due 
to  the  neutralizing  of  the  soap  on  the  fiber  by  the  acid;  as  it  is  claimed  that  as  a  result 
of  the  use  of  soap  (or  bast  soap)  in  the  dyebath  the  dyed  color  does  not  come  up  clear 
and  bright,  nor  does  mere  washing  in  water  correct  this  defect.  According  to  Ganswindt 
{Theorie  und  Praxis  der  modernen  Fdrberei,  part  II,  page  17)  the  use  of  the  subsequent 
brightening  bath  of  acid  is  not  required  when  the  silk  is  dyed  without  any  soap  in  the 
bath.  The  production  of  the  "  scroop  "  in  the  silk  is  probably  caused  by  the  hardening 
of  the  surface  of  the  fiber  by  the  action  of  the  acid.  In  place  of  tartaric  acid  for  this 
purpose,  the  cheaper  acetic  acid  may  also  be  used  (5  grams  per  liter).  Sulphuric  acid 
(2.5  grams  per  liter)  may  also  be  employed,  but  in  this  case  the  silk  should  be  rinsed 
slightly  after  treatment  with  the  acid. 


220         APPLICATION  OF  ACID  DY^S  TO  SILK,  COTTON,  ETC. 

250  cc.  of  water,  20  per  cent  of  alum,  20  per  pent  of  glaubersalt,  and  2  per  cent  of  Water 
Blue;  enter  a  skein  of  cotton  yarn  at  140°  F.,  raise  to  180°  F.  and  keep  at  that  temper- 
ature for  forty-five  minutes;  then  squeeze  and  dry  without  washing.  It  will  be  noticed 
that  a  rather  concentrated  or  "  short  "  bath  is  employed  and  that  even  then  the  exhaus- 
tion is  very  imperfect.  These  dyes  are  not  much  used  on  cotton  at  the  present  time, 
except  for  such  materials  as  curtains,  etc.,  where  bright  colors  are  desired  which  have 
good  fastness  to  light  and  where  fastness  to  washing  is  not  demanded.  To  show  the 
lack  of  fastness  to  washing  of  this  color,  plait  a  portion  of  the  dyed  sample  with  some 
strands  of  white  cotton  yarn,  and  scour  this  test  sample  in  a  dilute  soap  solution;  it 
will  be  found  that  the  color  will  wash  out  almost  completely.  When  applied  to  cotton, 
these  dyes  are  usually  known  as  "  alum  colors  "  because  that  salt  is  used  in  the  bath. 

Exp.  63.  Dyeing  in  a  Neutral  Salt  Bath. — This  method  is  generally  employed  for 
the  dyeing  of  bright  pale  shades  on  cotton  wath  the  acid  dyes.  Use  a  skein  of  bleached 
cotton  yarn,  and  dye  in  a  bath  containing  250  cc.  of  water,  10  grams  of  common  salt, 
and  10  per  cent  of  Eosin;  work  for  forty-five  minutes  at  a  temperature  of  140°  F.,  then 
squeeze  and  dry  without  washing.  The  large  amount  of  salt  employed  helps  to  better 
exhaust  the  bath,  as  the  dyestuff  is  less  soluble  in  salt  solutions.  The  bath,  however,  is 
in  no  wise  exhausted  and  should  be  employed  in  practice  for  a  "  standing  "  bath  for  the 
dyeing  of  subsequent  lots. 

Exp.  64.  Use  of  "  Blue  Mordant." — This  mordant  is  a  tartrate  of  aluminium,  and 
may  be  prepared  by  dissolving  22  parts  of  aluminium  sulphate  in  45  parts  of  water,  and 
then  adding  a  solution  of  4^  parts  of  tartaric  acid  dis.solved  in  20  parts  of  water,  after 
which  gradually  add  a  solution  of  Qh  parts  of  soda  ash  in  35  parts  of  water,  and  dilute 
the  whole  to  175  parts  with  water.  For  mordanting,  use  1  part  of  this  solution  to  30 
parts  of  water,  or  10  cc.  to  300  cc.  of  water.  Work  a  skein  of  cotton  yarn  in  a  bath 
containiTig  300  cc.  of  water,  10  cc.  of  "  blue  mordant,"  and  1  per  cent  of  Water  Blue 
6B  for  one-half  hour  at  1G0°  F.     Squeeze  and  dry  without  washing. 

Exp.  65.  Use  of  Sodium  Stannate  Mordant. — This  salt  is  easily  decomposed  when 
its  solution  is  boiled,  and  thus  liberates  oxide  of  tin  in  the  fiber.  It  is  used  as  follows: 
Steep  a  skein  of  cotton  yarn  for  one-half  hour  in  a  bath  containing  200  cc.  of  water  and 
5  grams  of  sodium  stannate  at  180°  F.  Remove  the  skein,  squeeze,  and  dye  in  a  bath 
containing  250  cc.  of  water  and  1  per  cent  of  Ponceau  4B  and  5  per  cent  of  alum;  entea* 
at  140°  F.,  gradually  raise  to  190°  F.,  and  dye  at  that  temperature  for  one-half  hour. 
Squeeze  and  dry  without  washing. 

Exp.  66.  After-treatment  of  an  Acid  Dye  with  Chrome. — Some  of  the  acid  dyes  on 
being  treated  after  dyeing  with  a  boiling  solution  of  chrome  (potassium  bichromate)  are 
changed  into  faster  and  deeper  colors.*  The  chrome  may  act  in  two  ways:  in  the  first 
place,  it  may  combine  with  the  dyestuff  to  give  a  permanent  color-lake  (similar  to  the 
mordant  dyes),  and  secondly,  it  may  cause  an  oxidation  of  the  dyestuff  whereby  a  new 
compound  is  obtained  on  the  fiber  which  is  faster  in  color  than  the  original  one.  Dye 
two  skeins  of  woolen  yarn  in  the  usual  manner  in  a  bath  containing  300  cc.  of  water,  10 
per  cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and  1  per  cent  of  Cloth  Red  GA. 
After  dyeing  fo.*-  one-half  hour,  lift  the  skeins  from  the  bath  and  add  2  per  cent  of  chrome. 
Re-enter  one  of  the  skeins,  and  continue  boiling  for  twenty  minutes.  Then  wash  and 
dry.     Compare  the  color  of  the  two  skeins,  and  it  will  be  noticed  that  the  chromed  one 

*  Sometimes  a  previous  treatment  with  a  mordant  of  chrome  and  bluestone  is 
recommended  for  the  purpose  of  giving  dyeings  faster  to  fulling,  and  more  especially  on 
shoddy  material.  The  wool  is  first  boiled  for  one  hour  in  a  bath  containing  2  per  cent 
of  chrome,  3  per  cent  of  bluestone,  and  2  per  cent  of  sulphuric  acid;  rinse  and  dye  in 
a  fresh  bath  containing  the  acid  dyestuff  and  a  small  quantity  (1  to  2  per  cent)  of  sul- 
phuric acid. 


EXPERIMENTAL  STUDIES 


221 


is  deeper  in  shade.  Test  the  fastness  of  the  dyeings  to  washing  in  the  following  manner: 
Take  a  portion  of  each  skein  and  plait  it  with  some  strands  of  white  woolen  yarn,  and 
then  scour  the  samples  so  prepared  in  a  lukewarm  dilute  soap  solution  containing  about 
5  grams  of  soap  per  liter.  Ne.xt  wash  in  fresh  water,  and  allow  the  two  tests  to  dry,  and 
compare  them  as  to  the  loss  of  color  and  as  to  the  amount  of  color  that  bleeds  into  the 
white  wool. 

Exp.  67.     Use  of  a  Chromotrop  Dye. — This  class  of  dyes  gives  red  or  brown  colors 
when  dyed  in  an  acid  bath,  but  the  color  so  obtained  is  of  little  importance.     When 


Fig.  144. — Warp  Dyeing  Machine  for  Long  Chain  System. 
(H.  W.  Butterworth  &  Sons  Co.) 


after-treated,  however,  with  solutions  of  metallic  salts  (such  as  chrome)  the  color  changes 
to  black  and  becomes  very  fast.  Prepare  a  bath  containing  300  cc.  of  water,  4  per  cent 
of  sulphuric  acid,  20  per  cent  of  glaubersalt,  and  6  per  cent  of  Chromotrop  FB;  dye  two 
skeins  of  woolen  yarn  in  this  bath  in  the  usual  manner  for  one-half  hour,  then  lift  and 
add  3  per  cent  of  chrome  and  2  per  cent  of  sulphuric  acid,  re-enter  one  of  the  skeins  and 
continue  boiling  for  twenty  minutes. 


CHAPTER  VIII 
REPRESENTATIVE  ACID  DYES 

1.  Nomenclature  of  Dyestufifs. — The  manner  of  naming  dyestuffs, 
unfortunately,  is  a  very  confused  matter.  In  the  early  days  of  dyestufi 
manufacture  the  name  given  to  a  coloring  matter  usually  had  some  refer- 
ence to  a  particular  quality  of  tone,  such  as  Malachite  Green,  Fuchsine, 
Croceine  Scarlet,  etc.,  or  was  given  as  a  courtesy  to  some  prominent  his- 
torical character,  such  as  Bismarck  Brown,  Victoria  Blue,  etc.  Names 
were  also  given  as  indicative  of  the  use  of  the  dye,  as  Cloth  Red,  Acid 
Magenta,  Chrome  Black,  etc.,  or  as  indicating  the  chemical  nature  of  the 
dyes,  such  as  Tartrazine  (derived  from  dioxy-tartaric  acid),  Azo  Rubine, 
Diazo  Black,  Methyl  Violet,  Metanil  Yellow,  etc. 

As  the  number  of  dyes  increased,  however,  and  as  the  number  of  dye- 
stuff  manufacturers  multiplied,  all  kinds  of  names  were  introduced,  and 
frequently  different  manufacturing  firms  complicated  the  matter  by  giving 
widely  dilTerent  names  to  the  same  product  in  an  attempt  to  establish  a 
proprietary  value  to  their  own  dye.  A  direct  cotton  blue,  for  instance, 
was  given  the  following  variety  of  names,  depending  on  the  manufacturer, 
although  they  all  related  to  exactly  the  same  product:  Diamine  Blue  BX, 
Benzo  Blue  BX,  Congo  Blue  BX,  Dianil  Blue  HG,  Naphthamine  Blue  BX, 
Azidine  Blue  BX,  Niagara  Blue  BX.  This  naturally  led  to  a  great  deal 
of  confusion,  which  increased  as  time  went  on.  Later  there  was  some  ten- 
dency towards  system  in  that  many  manufacturers  gave  class  names  to 
certain  lines  of  their  products,  for  instance,  the  general  Une  of  substantive 
cotton  dyes  received  the  following  names  from  different  firms : 

Diamine  Colors  (Cassella)  Titan  Colors  (Holliday) 

Benzo  Colors  (Bayer)  Hessian  Colors  (Leoniiardt) 

Oxamine  Colors  (Badische)  Columbia  Colors  (Berlin) 

Dianil  Colors  (Hochst)  Naphthamine  Colors  (Kalle) 

The  general  line  of  sulphur  dyes  also  received  special  class  names,  such  as: 

Sulphur  Colors  (Berlin)  Katigcn  Colors  (Bayer) 

Immedial  Colors  (Cassella)  Kryogene  Colors  (Badische) 

Thiogene  Colors  (Hochst)  Thiou  Colors  (Kalle) 

222 


NOMENCLATURE  OF  DYESTUFFS  223 

Since  the  war,  with  the  advent  of  many  new  dycstuff  manufacturers  in 
America  and  England,  these  class  names  have  been  further  multiplied; 
for  instance,  we  have  Erie  Colors,  Pontamine  Colors,  Amanil  Colors, 
Auwico  Colors,  etc. 

The  letters  frequently  to  be  noted  after  the  names  of  dyestuffs  are 
often  private  trade  distinctions  for  the  use  of  the  manufacturer  in  identify- 
ing the  color;  such  for  instance,  as  Brilliant  Croceine  MOOO,  Alizarine 
Blue  SAP  and  Diamine  Black  BH.  In  many  cases  these  letters  refer  to 
the  particular  shade  of  the  dyestuff,  as,  for  example,  B  stands  for  a  blue 
tone,  R  for  red,  G  (gelb)  or  Y  for  yellow.    We  have,  for  instance,  Methyl 


Fig.,  145. — ^Warp  Dyeing  Machine,  Single  Compartment, 

(H.  W.  Butterworth  &  Sons  Co.) 

Violet  B  and  Methyl  Violet  BB  or  2B,  which  would  indicate  that  the 
latter  dye  is  bluer  in  tone  than  the  former.  Also  we  have  Acid  Yellow  G 
and  Acid  Yellow  R,  meaning  that  the  former  is  of  a  greenish  tone  while 
the  latter  is  of  an  orange  tone  (reddish).  When  the  letter  X  is  used  it 
mostly  refers  to  a  concentrated  type ;  Sulphur  Black  AX  for  instance  would 
mean  that  the  dye  in  question  is  represented  as  a  specially  strong  type. 
The  letter  W  usually  designates  a  wool  dye;  L  means  a  light-fast  type  of 
dye;  while  S  refers  to  a  specially  soluble  dye.  In  some  cases  we  may 
have  letters  of  Roman  numerals  indicating  different  strengths  of  the  dye, 
as  with  Auramine  0  and  Auramine  I,  II,  III.  In  this  case  Auramine  O 
means  the  pure  strong  type  while  the  marks  I,  II,  and  III  refer  to  types 
more  and  more  diluted  in  strength. 


224  REPRESENTATIVE  ACID  DYES 

The  matter  is  still  further  complicated  by  the  fact  that  in  addition  to 
the  large  number  of  single  dyes  to  be  met  with,  there  are  also  a  large  numl^er 
of  mixed  dyes;  that  is  to  say,  a  green  dye,  for  example,  may  be  made  by 
suitably  mixing  a  yellow  and  blue  dye.  This  green  dye  is  usually  given 
some  particular  name  and  designating  letter  or  numlx^r  for  identification 
to  the  manufacturer,  Formyl  Blue  B,  for  instance,  is  a  bright  blue  dj-e- 
stuff  made  by  mixing  Formyl  Violet  S4B  (a  single  dye)  with  another  dye 
of  such  character  that  the  mixture  gives  a  blue.  In  order  to  cater  to 
convenience  of  the  dyer,  a  gi'eat  number  of  such  mixed  dyes  have  been 
brought  into  trade,  and  this  has  needlessly  added  to  the  multiplicity  of 
the  products  as  well  as  to  the  confusion  of  the  names.  It  would  be  far 
better  to  market  dyes  as  indi\'idual  products,  and  let  the  dyer  make  his 
own  compounds  and  mixtures  for  the  purpose  of  matching  colors. 

Attempts  have  l^een  made  to  systematize  and  classify  dyes  for  the  pur- 
pose of  simplifj'ing  their  nomenclature  and  thus  identifying  the  product 
by  some  imiversally  accepted  designation;  but  all  these  attempts  have 
been  more  or  less  abortive.  Perhaps  the  most  generally  accepted  classi- 
fication of  dyes  for  tliis  purpose  of  identification  is  the  numbered  list  of 
dyes  in  the  "  Dyestuff  Tables  "  of  Schultz.  These  tables  are  published 
ever^^  few  years  in  order  to  include  the  additional  dyes  appearing.  The 
last  edition  was  that  of  1914,  and  the  numbers  given  to  the  dyes  in  these 
tables  have  generally  been  adopted  during  the  past  few  years  where  iden- 
tification is  necessary.  The  same  scheme  will  be  adopted  in  this  book, 
and  where  it  is  especially  necessary  to  identify  a  dj'estuff,  the  Schultz 
number  will  be  given  in  parenthesized  italics;  as  for  example,  Rose  Ben- 
gale  {597),  the  number  meaning  that  this  dye  is  the  one  identified  in  the 
Schultz  Tables  under  597. 

There  are,  however,  a  large  number  of  dj^es  on  the  market  that  are  not 
to  be  found  in  the  Schultz  Tables.  Zambesi  Black,  for  instance,  is  a  well- 
known  dye,  and  one  wliich  was  largely  used  prior  to  the  war  (and  will 
presumably  again  be  an  miportant  it€m) ;  yet  it  is  not  Usted  or  identified 
in  Schultz  Tables.  This  is  also  true  of  a  numl^er  of  the  more  recent  vat 
dyes. 

The  following  is  a  list  arranged  alphabetically  of  the  various  trade 
names  of  various  groups  of  dyes,  which  will  help  to  identify  the  class  of  the 
dj'estuff  and  its  manufacturer. 


Group  Name 

Dye  Class 

Manufacturer 

Acid  Alizarine 

Acid  Chrome 

Hochst 

Acid  Anthracene 

.\cid  Chrome 

Bayer 

Acid  Chrome 

Acid  Chrome 

Bayer 

Acidol 

Acid 

Weiler 

Acidol  Chromate 

Acid  Chrome 

Weiler 

Acridine 

Basic 

Leonhardt 

GROUP   NAMES  OF  DYES 


225 


Group  Name 

Dye  Class 

Manufacturer 

Aetz 

Acid  (Discharged) 

Basle 

Algole 

Vat 

Bayer 

Alizadine 

Acid  Chrome 

British  Dyes 

Alizarine 

Chrome  and  Acid  Chrome 

Various 

Alizarine  Azo 

Acid  Chrome 

Durand 

Alizarol 

Acid  Chrome 

National 

Alkali 

Substantive 

Dahl 

Alphanol 

Acid                              V 

Cassella 

Amacid 

Acid 

Amer.  Anil.  Prod. 

Amanil 

Substantive 

Amer.  Anil.  Prod. 

Amidazol 

Sulphur 

Holliday 

Amido 

Acid 

Hochst 

Aminine 

Substantive 

Brassard 

Anachrome 

Acid  Chrome 

Brassard 

Anthra  Chroma te 

Acid  Chrome 

Leonhardt 

Anthra  Chrome 

Acid  Chrome 

Leonhardt 

Anthracene  Acid 

Acid  Chrome 

Cassella 

Anthracene  Chromate 

Acid  Chrome 

Cassella 

Anthracene  Chrome 

Acid  Chrome 

Cassella 

Anthracyanine 

Acid 

Bayer 

Anthracyl  Chrome 

Acid  Chrome 

Dahl 

Anthranol 

Acid  Chrome 

Dahl,  U.  S.  Color 

Anthraquinone 

Acid 

Badische 

Atlantamine 

Substantive 

Atlantic 

Atlantene 

Developed 

Atlantic 

Atlanthrene 

Chrome 

Atlantic 

Atlantole 

Acid 

Atlantic 

Auronal 

Sulphur 

Weiler 

Auto  Chrome 

Acid  Chrome 

Hochst 

Autogene 

Sulphur 

Poirrier 

Autol 

Pigment 

Badische 

Azidine 

Substantive 

Jager 

Azo 

Acid 

Various 

Azo  Acid 

Acid 

Various 

Azo  Alizarine 

Acid  Chrome 

Durand 

Azophor 

Coupled 

Hochst 

Benzamine 

Substantive 

Dahl 

Benzo 

Substantive 

Bayer 

Benzo  Chrome 

Substantive  (Chromed) 

Bayer 

Benzo  Fast 

Substantive 

Bayer 

Benzoform 

Substantive  (formaldehyde)  Bayer 

Benzoin 

Substantive 

Beyer  &  Kegel 

Benzo  Light 

Substantive  (light  fast) 

Bayer 

Benzonitrol 

Coupled 

Bayer 

Benzyl 

Acid 

Basle 

Biebrich 

Acid 

Kalle 

Brilliant  Alizarine 

Chrome 

Bayer 

Brilliant  Benzo 

Substantive 

Bayer 

Brilliant  Dianil 

Substantive 

Hochst 

Brilliant  Fat 

Oil  Soluble 

Basle 

Buffalo 

Acid 

National 

226 


REPRESENTATIVE  ACID  DYES 


Group  Name 
Caledon 
Cerasine 
Ceres 
Chicago 
Chloramine 
Chloranthrene 


Dye  Class 
Vat 

Spirit  and  Oil  Soluble 
Dyes  for  Lakes 
Substantive 
Substantive 
Vat 


Manufacturer 

Scottish  Dyes 

Cass.^lla 

Bayer 

Berlin 

Bayer,  Sandoz 

British  Dyes 


Fig.  146. — Machine  for  Doubling  Warps  Previous  to  Dyeing. 
(H.  W.  Butterworth  &  Sons  Co.) 


Chlorantine 

Substantive 

Basle 

Chlorazol 

Substantive 

British  Dyes 

Chromanthrene 

Chrome 

Levinstein 

Chrome  Fast 

Arid  Chrome 

Basle 

Chromo.xan 

Acid  Chrome 

Bayer 

Ciba 

Vat 

Basle 

Cibanone 

Vat 

Basle 

Columbia 

Substantive 

Berlin 

Congo 

Substantive 

Berlin 

GROUP   NAMES  OF   DYES 


227 


Group  Name 

Dye  Class 

Manufacturer 

Coomassie 

Acid 

Levinstein 

Cotton 

Substantive 

Various 

Cross  D3'e 

Sulphur 

British  Dyes 

Crumpsull 

Acid 

Levinstein 

Cyananthrol 

Acid 

Badische 

Diadem  Chrome 

Acid  Chrome 

HoUiday 

Diamine 

Substantive 

Cassella 

Diamine  Nitrazol 

Coupled 

Cassella 

Diamond 

Acid  Chrome 

Bayer 

Dianil 

Substantive 

Hochst 

Dianil  Fast 

Substantive 

Hochst 

Dianol 

Substantive 

Levinstein 

Diazanil 

Developed 

Hochst 

Diazine 

Basic 

Kalle 

Diazo 

Developed 

Bayer 

Diazo  Light 

Developed  (light  fast) 

Bayer 

Diazogen 

Developed 

Jager 

Diphenyl 

Substantive 

Geigy 

Direct 

Substantive 

Various 

Discharge 

Acid  (Dischargeable) 

Basle 

Domingo 

Acid 

Leonhardt 

Domingo  Alizarine 

Acid  Chrome 

Leonhardt 

Domingo  Chrome 

Acid  Chrome 

Leonhardt 

Duatol 

Dyes  for  Union  Goods 

Cassella 

Duranthrene 

Vat 

Levinstein 

Durindone 

Vat 

Levinstein 

Eboli 

Substantive 

Leonhardt 

EcHpse 

Sulphur 

Geigy 

Era  Chrome 

Acid  Chrome 

Levinstein 

Erganone 

Chrome,  Printing 

Badische 

Erie 

Substantive 

National 

Eric 

Acid 

Geigy 

Erio  Chromal 

Acid  Chrome 

Geigy 

Erio  Chrome 

Acid  Chrome 

Geigy 

Erweco-Ahzarine 

Acid  Chrome 

Wedekind 

Formal 

Substantive  (formaldehyde) 

Geigy 

Furrol 

Fur  Dyes 

Cassella 

Gallanil 

Acid 

Durand 

Gallo 

Chrome  Printing 

Bayer 

Glycine 

Substantive 

Kinzlberger 

Graphitol 

Lake  Colors 

Griesheim 

Guinea 

Acid 

Berlin 

Half-wool 

Dyes  for  Union  Goods 

Various 

Hansa 

Lake  Colors 

Hochst 

Helindone 

Vat 

Hochst 

Helio 

Lake  Colors 

Bayer 

Hessian 

Substantive 

Leonhardt 

Hydranthrene 

Vat 

Holliday 

Hydron 

Vat 

Cassella 

Hydrosulphon 

Sulphur 

Brassard 

Immedial 

Sulphur 

Cassella 

228 


REPRESENTATIVE  ACID  DYES 


Group  Name 

Dye  Class 

Manufacturer 

Indanthrenc 

Vat 

Badische 

Janus 

Basic 

Hochst 

Kashmir 

Acid 

Bayer 

Katigen 

Sulphur 

Bayer 

Kitoii 

Acid 

Basle 

Kyrogene 

Sulphur 

Badische 

Lanacyl 

Acid 

Cassella 

Lanasol 

Acid  Chrome 

Basle 

Leucol 

Vat 

Bayer 

Lissamine 

Acid 

Levinstein 

Lithol 

Lake  Colors 

Badische 

Mercerol 

Acid 

Holliday 

Metachrome 

Acid  Chrome 

Berlin,  Brotherton 

Methylene 

Basic 

Hochst 

Mikado 

Substantive 

Leonhardt 

Mining 

Acid 

Various 

Modern 

Printing  Colors 

Durand 

Monochrome 

Acid  Chrome 

Bayer,  Holliday 

Naka 

Fur  Dyes 

Hochst 

NaphthaminG 

Substantive 

Kalle 

Naphthol 

Acid 

Various 

Naphthj'lamine 

Acid 

Various 

Neoform 

Substantive  (formaldehyde) 

Basle 

Neptune 

Acid 

Badische 

Niagara 

Substantive 

National 

Nitrazo 

Coupled 

Jiiger 

Oil 

Oil  Soluble 

Various 

Omega  Chrome 

Acid  Chrome 

Sandoz 

Ortho 

Acid 

Berlin 

Osfa  Chrome 

Acid  Chrome 

Hruschau 

Osfamine 

Substantive 

Hruschau 

Osfanil 

Substantive 

Hruschau 

Osfathion 

Sulphur 

Hruschau 

Oxamine 

Substantive 

Badische 

Oxy  Chrome 

Acid  Chrome 

Griesheim 

Oxy  Diamine 

Substantive 

Cassella 

Palatine 

Acid 

Badische 

Palatine  Chrome 

Acid  Chrome 

Badische 

Para 

Coupled 

Bayer 

Parachrome 

Acid  Chrome 

Oxley 

Paramine 

Substantive 

Holliday 

Paranil 

Coupled 

Berlin 

Paranol 

Substantive 

U.  S.  Color 

Paraphor 

Coupled 

Hochst 

Permanent 

Lake  Colors 

Berlin 

Pheno 

Substantive 

Heller  &  Merz 

Phenochrome 

Chrome,  Printing 

Kalle 

Phenyl 

Acid 

Fran^aise 

Pigment 

Lake  Colors 

Hochst 

Pluto 

Substantive 

Bayer 

Polar 

Acid 

Geigy 

GROUP   NAMES  OF  DYES 


229 


Grouj)  Name 

Dye  Class 

Manufacturer 

Polyphenyl 

Substantive 

Geigy 

Pontacyl 

Acid 

Du  Pont 

Pontamine 

Substantive 

Du  Pont 

Pontochrome 

Acid  Chrome 

Du  Pont 

Primazine 

Lake  Colors 

Badische 

Pyrazol 

Substantive 

Sandoz 

Pyramine 

Substantive 

Badische 

Pyrogene 

Sulphur 

Basle 

Pyrol 

Sulphur 

Loonhardt 

Pyronal 

Oil  Soluble 

Dahl 

Renol 

Substantive 

Wcilcr 

Rhoduline 

Basic 

Bayer 

Rosanthrene 

Substantive 

Basle 

St.  Denis 

Substantive 

Poirrier 

Salicine 

Acid  Chrome 

Kalle 

Serichrome 

Acid  Chrome 

National 

Seto 

Acid 

Geigy 

Sita 

Lake  Colors 

Weiler 

Solochrome 

Chrome 

Levinstein 

Stilbene 

Substantive 

Various 

Sulphanil 

Substantive 

Kalle 

Sulphine 

Sulphur 

Noctzol,  Istel  &  Co, 

Sulpho 

Sulphur 

Holliday 

Sulphogene 

Sulphur 

Du  Pont,  Basle 

Sulphon 

Acid 

Bayer 

Sulphon  Acid 

Acid 

Bayer 

Sulphur 

Sulphur 

Berlin,  National 

Sulphurol 

Sulphur 

Dahl 

Sultan 

Substantive 

British  Dyes 

Supramine 

Acid 

Bayer 

Superchrome 

Acid  Chrome 

National 

Tannate 

Basic 

Dahl 

Thiazine 

Substantive 

Bayer 

Thio  Indigo 

Vat 

Kalle 

Thiogene 

Sulphur 

Hochst 

Thion 

Sulphur 

Kalle 

Thional 

Sulphur 

Sandoz 

Thionol 

Sulphur 

Levinstein 

Thionone 

Sulphur 

Holliday 

Thiophor 

Suljjhur 

Jager 

Thioxine 

Sulphur 

Griesheim 

Titan 

Substantive 

British  Dyes 

Toluylene 

Substantive 

Griesheim 

Triatol 

Dyes  for  Union  Goods 

Dorr 

Triazol 

Substantive 

Griesheim 

Trisulphon 

Substantive 

Sandoz 

Tyemond 

Acid 

Holliday 

Ultra 

Chrome 

Sandoz 

Ursol 

Fur  Dyes 

Berlin 

Victoria 

Acid 

Various 

Vidal 

Sulphur 

Poirrier 

230  REPRESENTATIVE  ACID  DYES 

Group  Name  Dye  Class  Manufacturer 

Vulcan  Sulphur  Levinstein 

Wakefield  Acid  Brassard 

Wool  Acid  \"arious 

Xj'lene  Acid  Sandoz 

Zambesi  Developed  Berlin 

2.  DyestufE  Manufacturers.^Owing  to  the  complex  nomenclature  of 
dyes  depending  to  a  considerable  extent  on  the  particular  manufacturer,  it 
reallj'  becomes  necessaiy  at  times  to  include  the  name  of  the  manufacturer 
with  the  dyestuff  in  order  properl}'  to  identify  it.  Previous  to  the  war  by 
far  the  greater  part  of  the  dyes  sold  throughout  the  world  were  made  by 
Gemian  manufacturers  and  there  were  only  a  small  scattering  of  other 
manufacturers  through  England,  France,  Switzerland  and  America. 
Since  the  war,  however,  the  dyestuff  industiy  has  been  developed  to  large 
proportions  in  other  nations  besides  Germany,  so  that  now  the  matter  is 
still  further  complicated  by  a  greatly  extended  list  of  manufacturers. 
For  the  convenience  and  instruction  of  the  reader,  a  list  of  the  principal 
dyestuff  manufacturers  in  cUfferent  countries  is  given  in  an  appended  list. 
There  will  also  be  found  a  designated  abbreviation  which  may  be  used  at 
tunes  in  connection  with  particular  dj'estuffs  in  order  to  identify  the 
product.  Naturally  the  author  has  taken  pains  carefully  to  avoid,  as  far 
as  possible,  reference  to  particular  manufacturers  or  any  tendency  to  give 
prominence  to  one  make  of  color  over  another.  At  the  present  time,  when 
most  of  the  patents  covering  the  principal  dyes  have  run  out,  the  same 
dyestuff  is  made  by  a  number  of  manufacturers,  and  generally  there  is 
httle  or  no  variation  in  the  type  and  quality  of  the  different  makes.  Un- 
fortunately, however,  the  names  of  manj^  of  these  dyes  have  been  trade- 
marked  and  of  course  these  names  remain  the  property  of  the  particular 
manufacturer,  although  the  dye  may  be  universal^  kno\^Tl  commercially 
by  its  original  trade-marked  name.  Diamine  Blue  2B,  for  instance, 
is  a  well-known  cotton  dyestuff,  and  is  made  by  a  large  number  of  firms; 
but  the  name  "  Diamine  "  is  a  trade-mark  of  a  particular  manufacturer 
(Leopold  Cassella  &  Co.,  of  Frankfort,  Germany),  and  therefore  this  dye  is 
to  be  met  with  under  a  variety  of  names,  some  aiso  trade-marked  (such  as 
Benzo  Blue  2B,  Pont  amine  Blue  2B)  and  others  not  (such  as  Direct 
Blue  2B). 

LIST  OF  PRINCIPAL  DYESTUFF  MANUFACTURERS 

(a)  United  States 

National  Aniline  and  Chemical  Co.  (National) 
E.  I.  du  Pont  de  Nemours  &  Co.  (Du  Pont) 
Grasselli  Chemical  Co.  (Grasselli) 
Newport  Chemical  Works  (Newport) 
Heller  &  Merz  Co.  (H.  &  M.) 


DYESTUFF  MANUFACTURERS  231 

John  Campbell  &  Co.  (Campbell)  Buttcrworth-Judson  Corp.  (B.  &  J.) 

Atlantic  Dyestuff  Co.  (Atlantic)  Dow  Chemical  Co.  (Dow) 

Pharma  Chemical  Co.  (Pharma)  Peerless  Color  Co.  (Peer) 

Essex  Aniline  Works  (Essex)  Calco  Chemical  Co.  (Calco) 

Central  Dyestuffs  &  Chemical  Co.  (Cen-      Dye    Products    &    Chemical    Co.    (Dye 

tral)  Prod) 

Althouse  Chemical  Co.  (Althouse)  Cincinnati  Chemical  Works  (Cin) 

E.  C.  Klipstein  &  Sons'  Co.  (Klip)  Crotor    Color    &    Chemical    Co.     (Cro- 
Noil  Color  &  Chemical  Co.  (Noil)  ton) 

United    States    Color    &    Chemical    Co.       American  Aniline  Products  (A.  A.  P.) 
(U.  S.  Col.) 

(b)  Germany 

Badische  Anilin  und  Soda  Fabrik  (Badische) 

Actien-Gesellschaft  fiir  Anilin-Fabrikation;    Berlin  Aniline  Works  (Berlin) 

Farbenfabriken  vorm.  Fried.  Bayer  &  Co.  (Bayer) 

Leopold  Cassella  &  Co.  (Cassella) 

Farbwerke  vorm.  Meister  Lucius  &  Briining  (Hochst) 

Chemische  Fabrik,  Griesheim-Elektron  (Greisheim) 

Farbwerk  Miilheim  vorm.  A.  Leonhardt  &  Co.  (Leonhardt) 

Kalle  &  Co.  (Kalle) 

Leipziger  Anilinfabrik  Beyer  &  Kegel  (Beyer  &  Kegel) 

Carl  Jager  Anilinfarbenfabrik  (Jiiger) 

R.  Wedekind  &  Co.  (Wedekind) 

Chemikalienwerk  Grieshcim  (Noetzel  &  Istel) 

Chemische  Fabriken  vorm.  Weiler-ter-Meer  (Weiler) 

Wulfing,  Dahl  &  Co.  (Dahl) 

(c)  England 

British  Dyestuff  Corp.  (British  Dyes) 

L.  B.  Holliday  &  Co.  (HoUiday) 

Levinstein,  Ltd.  (Levinstein),  now  joined  with  British  Dyestuff  Corp. 

Clayton  Aniline  Co.  (Clayton) 

F.  a  Brassard  &  Crawford  (Brassard) 
The  Lazard-Godchaux  Co.  (Lazard) 

J.  C.  Oxley's  Dyes  &  Chemicals  (Oxley) 
Brotherton  &  Co.  (Brotherton) 
Barking  Chemical  Co.  (Barking) 
British  Alizarine  Co.  (Br.  Alizarine) 
Scottish  Dyes,  Ltd.  (Scot.  Dyes) 

(d)  Switzerland 

Gesellschaft  fiir  Chemiscne  Industrie  in  Basle  (Basle) 
Farbwerke  vorm.  L.  Durand  Huguenin  &  Co.  (Durand) 
J.  R.  Geigy  (Geigy) 
Sandoz  Chemical  Works  (Sandoz) 

(e)  France 

Societe  Anonyme  des  Matieres  Colorantes  (Poirrier) 

John  Casthelaz,  Bruere  et  Cie.     (Gasthelaz) 

Societe  Nouvelle  de  Couleurs  d' Aniline  de  Pantin  (Pantin) 

Compagnie  Nationale  de  Matieres  Colorantes  et  de  Produits  Chimiques  (C.  N.  M.  C.) 


232 


REPRESENTATIVE  ACID  DYES 


Laroche  <t  Juillard  (Laroche) 

Compagaie  Frau^uise  de  Produits  Chimiques  et  Matieres  Colorantes  (Frangaisc) 

(f)  Italy 

Society  Italiana  Prodotti  Esplodenti 
Society  Italiana  Colori  Artificial! 
Fabbrica  Italiana  Matcrie  Coloranti  Bonclli 
Industria  Nazionale  Colori  Anilina 
Chimica  Lombarda  Bianchi 

3.  List  of  the  Principal  Acid  Dyestufifs. — The  acid  d3^es  to  be  met  with 
upon  the  market  at  the  present  time  inchule  a  very  large  number.  This  is 
further  increased  by  the  fact  that  many  different  names  are  frequently 
given  to  the  same  dyestuff  by  different  manufacturers  and  dealers,  and  still 
further  by  the  use  of  mixed  dyes  to  produce  different  shades  and  tones. 
It  would  be  practically  impossible  to  give  a  complete  list  of  all  the  acid 
dyes  in  trade,  but  the  following  will  give  a  fair  idea  of  the  principal  dyes. 
They  are  roughly  classified  according  to  color. 


Acid  Carmoisine 

Acid  Cerise 

Acid  Fuchsine 

Acid  Magenta 

Acid  Maroon 

Acid  Red 

Acid  Rhodamine 

Acid  Rosamine 

Acid  Ponceau 

Alkali  Fast  Red 

Amaranth 

Amido  Naphthol  Red 

Anisoline 

Anthracene  Red 

Apollo  Red 

Archil  Substitute 

Azo  Acid  Carmine 

Azo  Acid  Fuchsine 

Azo  Acid  Rubins 

Azo  Acid  Magenta 

Azo  Bordeaux 

Azo  Cardinal 

Azo  Carmine 

Azo  Coccine 

Azo  Cochineal 

Azo  Crimson 

Azo  Eosin 

Azo  Fuchsine 

Azo  Graphic  Red 

Azo  Grenadine 

Azo  Orseille 


(a)  Red 

Azo  Phloxine 

Azo  Red 

Azo  Rhodine 

Azo  Rubine 

Benzyl  Red 

Biebrich  Acid  Red 

Biebrich  Scarlet 

Bordeaux 

Brilliant  Acid  Carmine 

Brilliant  Bordeaux 

Brilliant  Carmoisine 

Brilliant  Cochineal 

Brilliant  Crocoine 

Brilliant  Double  Scarlet 

Brilliant  Fast  Red 

Brilliant  Orseille 

Brilliant  Ponceau 

Brilliimt  Rubine 

Brilliant  Scarlet 

Brilliant  Sulphon  Red 

Cardinal 

Cardinal  Red 

Carmoisine 

Ccrasine 

Chromazon  Red 

Ciiromotrop 

Chromotrop  2R 

Clayton  Cloth  Red 

Cloth  Red 

Cloth  Scarlet 

Coccme 


Cocoinine 

Cochineal  Red 

Cochineal  Scarlet 

Cotton  Scarlet 

Cresol  Red 

Croceine 

Croceine  Scarlet 

Crystal  Ponceau 

Crystal  Scarlet 

Cj^anosine 

Double  Brilliant  Scarlet 

Double  Ponceau 

Double  Scarlet 

Emin  Red 

Eosamine 

Eosin 

Eosin  Scarlet 

Erythrine 

Erj'throsine 

Fast  Acid  Eosin 

Fast  Acid  Fuchsine 

Fast  Acid  Phloxine 

Fast  Bordeaux 

Fast  Claret  Red 

Fast  Crimson 

Fast  Fuchsine 

Fast  Ponceau 

Fast  Red 

Fast  Scarlet 

Florida  Red 

Guinea  Bordeaux 


PRINCIPAL  ACID   DYES 


233 


Guinea  Carmine 
Lake  Scarlet 
Lanafuchsine 
Leveling  Red 
Mars  Red 

Merccrine  Wool  Red 
Mercerine  Wool  Scarlet 
Milling  Red 
Milling  Scarlet 
Naphthorubine 
Naphthol  Red 
Naphthol  Scarlet 
Naphtliylamine  Red 
New  Claret 
New  Coccine 


New  Red 
Orcelline 
Orseille  Red 
Palatine  Red 
Palatine  Scarlet 
Phloxine 
Ponceau 
Pyrotine  Red 
Roccelline 
Rock  Scarlet 
Rosazeine 
Rose  Bengale 
Rosinduline 
Roxamine 
Salicine  Red 


Scarlet 
SUk  Red 
Silk  Scarlet 
Sorbine  Red 
Sulphon  Carmine 
Tolanc  Red 
Tyemond  Red 
Tyemond  Scarlet 
Victoria  Rubine 
Victoria  Scarlet 
Violamine 

Wakefield  Acid  Red 
Wakefield  Ponceau 
Wool  Red 
Wool  Scarlet 


Fig.  147. — Machine  for  Splitting  Warps  after  Dyeing. 
(H.  W.  Butterworth  &  Sons  Co.) 


Aniline  Orange 
Aurantia 
Brilliant  Orange 
Croceine  Orange 
Crystal  Orange 
Gold  Orange 


(b)  Orange 

Kermesine  Orange 
Mandarin  G 
Milling  Orange 
Orange  I 
Orange  II 
Orange  IV 


Orange  R,  G,  etc. 
Palatine  Orange 
Pyrotine  Orange 
Tyemond  Orange 
Wool  Orange 


234 


REPRESENTATn'E  ACID  DYES 


Acid  Yellow 
Alkali  Yellow 
Alpine  Yellow 
Azo  Acid  Yellow 
Azo  Flavine 
Azo  Yellow 
Brilliant  Yellow 
Chinoline  Yellow 
Chrysoine 
Cinercine 
Citronine 
Curcumine 
Fast  Yellow 
Fast  Light  Yellow 


Acid  Green 
Agalma  Green 
Alkali  Fast  Green 
Alizarine  Green 
Alizarine  Cyanine  Green 
Anthracene  Acid  Green 
Benzyl  Green 
Brilliant  Acid  Green 
Brilliant  Milling  Green 
Cyanole  Green 


Acid  Blue 

Acid  Peacock  Blue 

Alizarine  Blue  SAP,  SAE 

Alizarine  Pure  Blue 

Alizarine  Sapphire 

Alkali  Blue 

Aljjhazurine 

Anthra  Cyanine 

Anthracene  Blue 

Azine  Blue 

Azo  Acid  Blue 

Azo  Dark  Blue 

Azo  Marine  Blue 

Azo  Navy  Blue 

Bavarian  Blue 

Benzyl  Blue 

Biebrich  Acid  Blue 

Blackley  Blue 

Brilliant  Blue 

Brilliant  Silk  Blue 

Carmine  Blue 

China  Blue 

Cloth  Blue 


(c)  Yellow 

Flavaniline 
Flavazine 
Golden  Yellow 
Helianthine 
Indian  Yellow 
Martius  Yellow 
Mercerol  \Vool  Yellow 
Metanil  Yellow 
Milling  Yellow 
Naphthol  Yellow 
Naphthol  Yellow  S 
Naphthyla  mine  Yellow 
New  Y''ellow 


(d)  Green 

Cyprus  Green 
Diamond  Green 
Domingo  Green 
Eboli  Green 
Fast  Acid  Green 
Fast  Green 
Fast  Green  Bluish 
Fast  Light  Green 
Guinea  Green 
Kiton  Green 

(e)  Blue 

Coomassie  Acid  Blue 

Coomassie  Navy  Blue 

Copper  Blue 

Cotton  Blue 

Cyanine 

Cyanole 

Cyprus  Blue 

Disulphine  Blue 

Durasol  Acid  Blue  B 

Eriochlorine 

Eriocyanine 

Erioglaucine 

Ethyl  Blue 

Fast  Acid  Blue 

Fast  Blue 

Fast  Blue  Black 

Fast  Blue  for  Wool 

Fast  Sky  Blue 

Fast  Wool  Cyanone 

Fast  Wool  Blue 

Fluorescent  Blue 

Formyl  Blue 

Full  Blue 


Persian  Yellow 
Picric  Acid 
Quinoline  Yellow 
Resorcine  Yellow 
Solid  Yellow 
Sun  Yellow 
Tartrazine 
Tropa'oline 
Tyemond  Yellow 
Uranine 
Victoria  Yellow 
Wool  Yellow 
Xanthamine 


Light  Green 
Lissamine  Green  B 
Milling  Green 
Naphthaline  Green 
Naphthol  Green 
Neptune  Green 
Night  Green 
Patent  Green 
Wool  Green  S 


Gallanil  Indigo 
Gallocj^anine 
Gallazin  A 
Gentiana  Blue 
Indigo  Blue 
Indigo  Carmine 
Indigo  Extract 
Indigo  Substitute 
Indigotine 
Indocyanine 
Induline 
Intensive  Blue 
Ketone  Blue 
Kiton  Blue 
Lanacyl  Blue 
Lanacyl  Marine  Blue 
Lazuline  Blue 
Lyons  Blue 
Marinol  Acid  Blue 
Marine  Blue 
Methane  Dark  Blue 
Methyl  Alkali  Blue 
Methyl  Soluble  Blue 


PRINCIPAL  ACID   DYES 


235 


Milling  Blue 
Naphthaline  Blue 
Naphthazine  Blue 
Naphthol  Blue 
Naphthyl  Blue 
Navy  Blue 
Neptune  Blue 
New  Patent  Blue 
Night  Blue 
Opal  Blue 


Acid  Mauve 
Acid  Violet 
Alkali  Violet 
Azo  Acid  Violet 
Azo  Wool  Violet 
Benzal  Violet 
Benzyl  Violet 
Biebrich  Acid  Violet 


Patent  Blue 
Patent  Marine  Blue 
Patent  Neutral  Blue 
Peri  Wool  Blue 
Pure  Blue 
Sapjjhire  Blue 
Silk  Blue 
Solid  Blue 
Soluble  Blue 
Spirit  Blue 

(f)  Violet 

Ethyl  Acid  Violet 
Fast  Acid  Violet 
Fast  Sulphon  Violet 
Fast  Violet 
Fast  Wool  Violet 
Formyl  Violet 
Guinea  Violet 
Lanacyl  Violet 


Sulphocyanine 
Sulphon  Acid  Blue 
Thiocarmine 
Turquoise  Blue 
Urania  Blue 
Victoria  Marine  Blue 
Water  Blue 
Wool  Blue 
Wool  Marine  Blue 


Lissamine  Violet  2  R 
Naphthyl  Violet 
Neutral  Violet 
Red  Violet 
Regina  Violet 
Victoria  Violet 
Violamine 
Wool  Violet 


Fig.  148. — Warp  Dyeing  Machine.     (Zittauer.) 


Acid  Brown 
Azo  Brown 
Bismarck  Acid  Brown 
Bronze  Acid  Brown 
Chestnut  Brown 


Acid  Black 
Agalma  Black 
Alizarine  Black 


(g)  Brown 

Chromogen 
Clayton  Wool  Brown 
Dark  Acid  Brown 
Fast  Brown 

(h)  Black 

Amido  Naphthol  Black 
Aniline  Gray 
Anthracene  Acid  Black 


Marron 

Naphthol  Brown 
Naphthylamine  Brown 
Ilesorcinc  Brown 


Anthracite  Black 
Azo  Acid  Black 
Azo  Black 


236 


REPRESENTATIVE  ACID  DYES 


Azo  Merino  Black 
Biebrich  Patent  Black 
Brilliant  Black 
Buffalo  Blacks 
Burl  Black 
Cashmere  Black 
Coomassie  Black 
Coomassie  Blue  Black 
Coomassie  Fast  Black 
Copper  Black 
Deep  Black 
Domingo  Acid  Black 
Domingo  Azo  Black 
Domingo  Blue  Black 


Domingo  Violet  Black 
Durol  Black 
Ethyl  Black 
Mercerol  Wool  Black 
Methane  Black 
Naphtacyl  Black 
Naphthaline  Acid  Black 
Naphthol  Black 
Naphthyl  Blue  Black 
Naphthylamine  Black 
Nerol 

New  Victoria  Black 
Nigrosine 


Norwood  Black 
Palatine  Black 
Patent  Palatine  Black 
Phenol  Black 
Phenj'lamine  Black 
Phenylene  Black 
Silk  Black 
Sudan  Black 
Victoria  Black 
Wakefield  Acid  Black 
Wool  Black 
Wool  Deep  Black 
Wool  Gray 


4.  Experimental.  Exp.  68.  Representative  Acid  Dyes  on  Wool. — Dye  test  skeins  of 
woolen  yarn  in  baths  containing  300  cc.  of  water,  20  per  cent  of  glaubersalt,  4  per 
cent  of  sulphuric  acid,  and  1  per  cent  respectively  of  the  following  dyestuffs: 


Naphthol  Red  EB 
Emin  Red 
Tartrazine 
Naphthol  Yellow  S 
Alizarine  Blue  SAE 


Acid  Violet  oBF 
Patent  Blue  V 
Orange  II 
Wool  Blue  2B 
Acid  Green 


Enter  at  140°  F,,  gradually  raise  to  the  boil,  and  continue  at  that  temperature  for  one- 
half  hour;  wash  well  and  dry.  These  test  skeins  are  to  be  preserved  for  the  purpose  of 
testing  the  colors  for  fastness  to  various  agencies. 

Exp.  6£.  Representative  Acid  Dyes  on  Cotton.— Dj'e  test  skeins  of  cotton  j'arn  in 
baths  containing  200  cc.  of  water,  20  per  cent  of  alum,  and  50  per  cent  of  common  salt 
at  a  temperature  of  180°  F.  for  one  hour.  Wring  out  and  drj-  without  washing.  Pre- 
serve the  dyed  skeins  for  the  purpose  of  testing  the  colors  for  fastness. 

Use  10  per  cent  of  the  following  dyestuffs: 


Brilliant  Orange  G 
Ponceau  4R 
Rose  Bengale 
Methyl  Blue 


Brilliant  Croceine  M 
Metanil  Yellow 
Erj'throsine  B 
Irisamine  G 


Exp.  70.  Representative  Acid  Dyes  on  Silk. — Dj-e  test  skeins  of  silk  yarn  in  baths 
containing  150  cc.  of  water,  15  cc.  of  boiled-off  liquor,  and  acidify  with  sulphuric  acid. 
Dye  for  one  hour  at  180°  F.     Wash  well  and  brighten  with  tartaric  acid. 

Use  2  per  cent  of  the  following  dyestuffs: 


Acid  Magenta 
Acid  Violet  4RS 
Methyl  Blue  for  silk 
Orange  II 
Lyons  Blue 


Crj-stal  Ponceau  6R 

Cyanole  BB 

Acid  Green 

Azo  Fuchsine 

SUk  Black  4BF  6  per  cent. 


CHAPTER  IX 

STRIPPING  OF  COLORS;    TESTING  THE  FASTNESS  OF  DYES 

1.  Stripping  of  Dyed  Fabrics. — It  is  frequently  necessary  to  "  strip  " 
or  remove  the  color  from  dyed  materials.  This  is  especially  true  of  shoddy 
(recovered  wool)  which  has  been  obtained  from  mixtures  of  various  colors. 
The  object  of  the  stripping  is  to  obtain  a  light-colored  bottom  on  which  to 
dye  another  color.  The  following  are  the  chief  methods  of  stripping 
shoddy : 

(1)  By  steeping  for  six  to  eight  hours  (or  overnight)  in  a  lukewarm 
solution  of  soda  ash  containing  1  lb.  of  soda  ash  to  10  gallons  of  water. 
This  treatment  will  remove  a  considerable  number  of  the  more  fugitive 
acid  dyes.  Boiling  in  a  solution  of  ammonia  (2  lbs.  to  10  gallons)  is  also 
very  effective  with  many  acid  dyes  and  does  less  injury  to  the  fiber. 

(2)  Boil  for  thirty  minutes  in  a  solution  containing  2  to  5  lbs.  of  ammo- 
nium acetate  to  100  gallons  of  water.  This  is  also  suitable  for  many  acid 
dyes,  and  there  is  very  little  damage  to  the  material. 

(3)  Boil  for  one-half  to  one  hour  in  a  liquor  containing  3  to  7  per  cent 
of  chrome  and  3  to  10  per  cent  of  sulphuric  acid  (based  on  the  weight  of 
the  material).  This  method  will  strip  a  number  of  the  fast  alizarine  and 
mordant  colors.  The  material  at  the  same  time  also  becomes  mordanted 
for  subsequent  dyeing  with  fast  colors. 

(4)  Boil  for  thirty  minutes  in  a  bath  containing  3  to  5  per  cent  of  sul- 
phuric acid  (or  1^  to  2  per  cent  of  formic  acid,  or  8  to  10  per  cent  of  acetic 
acid)  and  3  to  5  per  cent  of  Decroline  (or  Hydraldite).  These  latter  strip- 
ping agents  are  hydrosulphite  compounds,*  and  will  very  effectively 
remove  a  large  number  of  colors  from  shoddy.  Though  their  cost  is  rela- 
tively high  their  efficiency  is  also  high. 

Stripping  at  times  must  also  be  resorted  to  when  too  heavy  a  shade  is 
obtained  in  dyeing,  and  it  is  necessary  to  remove  some  of  the  color  on  the 
fiber  to  match  a  shade.  In  the  case  of  woolen  materials,  especially  where 
acid  dyes  are  used,  boiling  in  a  bath  containing  a  considerable  quantity  of 
glaubersalt  will  often  take  off  considerable  color.  Also  boiling  in  a  bath 
containing  ammonium  acetate  is  very  efficacious.     In  cotton  dyeings, 

*  These  stripping  agents  are  usually  basic  zinc  hydrosulphite  compounds  or  formal- 
dehyde compounds  of  hydrosulphites. 

237 


238         STRIPPING  OF  COLORS;  TESTING  THE  FASTNESS  OF  DYES 

where  substantive  colors  arc  used,  boiling  in  fresh  water  will  gcnerall}-  bring 
down  the  color  considerably. 

For  stripping  the  different  classes  of  dyes  in  cases  where  the  color  has 
come  out  uneven  or  has  been  overdyed,  the  following  methods  are  sug- 
gested : 

(a)  Acid  Colors. — Boil  with  a  rather  strong  solution  of  glaubersalt,  or 
boil  in  a  solution  of  ammonia  water.  The  more  resistant  colors  may  be 
stripped  down  with  hydrosulphite. 

(b)  Mordant  Colors. — These  are  usually  rather  difficult  to  remove  and 
also  uneven  shades  being  difficult  to  correct  must  often  be  redyed  to  a 
darker  color  or  to  black.  Sometimes  stripping  can  be  partially  effected 
by  boiling  the  dyed  wool  in  a  fairly  strong  solution  of  sulphuric,  hydro- 


FiG.  149. — Warp  Dyeing  Machine.     (Fries.) 


chloric  or  oxalic  acid  wherebj^  the  dyestuff  color-lake  is  more  or  iCSs  decom- 
posed. By  succeeding  the  acid  treatment  with  a  warm  ammonia  bath  the 
dye  that  is  split  away  from  the  mordant  may  be  removed. 

(c)  Substantive  Dyes  on  Cotton. — These  may  be  partially  stripped  by 
boiling  in  water  containing  a  small  amount  of  soda  ash  in  solution.  If 
more  strenuous  methods  are  desired  use  hydrosulphite,  titanous  chloride 
or  a  weak  solution  of  bleaching  powder. 

(d)  Sulphur  Dyes  on  Cotton. — For  a  light  stripping  run  through  a  hot 
solution  of  sodium  sulphide;  a  more  vigorous,  or  even  complete  stripping 
may  be  obtained  by  treating  the  dyed  material  in  a  bath  of  bleaching 
powder  at  4  to  5°  Tw.  and  acidulating  with  acetic  acid. 

2.  Experimental.  Exp.  71.  Stripping  of  Substantive  Colors  with  Chloride  of 
Lime. — Take  one  of  the  skeins  of  cotton  yarn  which  has  been   dj'ed  with   Benzopur- 


QUALITIES  OF  FASTNESS  239 

purine  in  a  previous  experiment,  and  steep  it  for  one-half  hour  in  a  cold  solution  of 
chloride  of  lime  at  2°  Tw.;  then  squeeze  and  pass  through  a  cold  dilute  solution  of 
sulphuric  acid  for  ten  minutes;  then  wash  well,  soap  and  dry.  Preserve  a  sample 
of  the  color  before  this  treatment  and  compare  it  with  the  color  as  finally  obtained. 

Exp.  72.  Stripping  Substantive  Colors  with  Titanous  Salts. — Take  another  of  the 
skeins  of  cotton  yarn  which  has  been  dyed  with  Bcnzopuri)urine  as  above,  and  steep  it 
for  one-half  hour  in  a  solution  of  titanous  sulphate  containing  5  cc.  of  the  liquid  to  300 
cc.  of  water;  then  gradually  warm  to  180°  F.;  squeeze,  and  wash  well  in  fresh  water. 
Preserve  a  sample  of  the  color  before  treatment  and  compare  it  with  the  color  as  finally 
obtained. 

Exp.  73.  Stripping  Substantive  Colors  with  Hyraldite. — This  compound  is  a  deriva- 
tive of  sodium  hydrosulphitc  with  formaldehyde,  and  possesses  very  strong  reducing 
properties.  Take  one  of  the  skeins  of  cotton  yarn  dyed  with  Benzopurpurine  as 
above,  and  work  it  in  a  bath  containing  300  cc.  of  water,  5  per  cent  of  Ilydraldite 
A,  and  3  per  cent  of  acetic  acid;  enter  cold,  and  gradually  bring  to  the  boil,  then 
add  3  per  cent  more  of  acetic  acid  and  continue  boiling  for  fifteen  minutes.  Then 
remove  the  skein  and  wash  well  in  fresh  warm  water.  Preserve  a  sample  of  the  skcia 
before  treatment  and  compare  it  with  the  color  as  finally  obtained. 

3.  Fastness  of  Dyes. — The  fastness  of  a  dye  refers  to  the  abihty  of  the 
color  produced  by  it  to  withstand  the  destructive  effect  of  certain  agencies 
acting  upon  it.  No  dyestuff  of  organic  nature  can  be  considered  as  abso- 
lutely fast;  that  is  to  say,  the  color  produced  by  it  can  be  changed  or 
destroyed  by  one  means  or  another.  The  fastness  of  a  color,  however, 
must  be  considered  with  reference  to  those  agencies, acting  upon  it  normally 
under  the  customary  conditions  of  use  and  wear.  These  conditions  vary 
greatly  depending  on  the  character  of  the  goods  to  which  the  color  is  applied. 
To  the  ordinary  consumer  of  dyed  goods,  however,  the  most  usual  qualities 
of  fastness  required  are  reasonable  resistance  to  the  action  of  light  and 
washing  (treatment  with  soap  and  hot  water).  To  the  manufacturer 
of  the  goods,  however,  and  to  the  dyer  of  the  color,  the  qualities  of  fastness 
must  be  considered  in  a  broader  manner,  and  the  dye  must  be  selected  with 
reference  to  its  ability  to  produce  a  color  that  will  satisfactorily  meet  the 
requirements  of  the  goods  both  in  the  course  of  manufacture  and  in  subse- 
quent wear.  The  dyes  for  hat  felts,  for  example,  as  far  as  the  use  of  the 
material  goes,  require  only  a  good  fastness  to  light,  and  there  is  no  need 
of  a  fastness  to  washing,  because  hats  are  not  washed.  But  in  the  course 
of  the  manufacture  of  the  hat,  the  felt  form  after  it  is  dyed  has  to  pass 
through  a  number  of  operations  to  all  of  which  the  color  must  be  fast;  for 
instance,  it  is  hot-pressed  on  forms  and  is  subjected  to  rather  high  tempera- 
tures; it  is  steamed,  and  usually  stiffened  by  the  use  of  various  sizing 
materials.  So  in  addition  to  the  required  fastness  to  light,  a  dye  for  use 
on  hat  felts  must  also  be  fast  to  hot-pressing  and  steaming.  On  the  other 
hand,  dyes  employed  for  coloring  hosiery  need  not  be  particularly  fast  to 
light,  but  they  must  be  very  fast  to  washing,  and  furthermore,  must  be  fast 
to  perspiration  and  rubbing  (crocking). 


240        STRIPPING  OF  COLORS;  TESTING  THE  FASTNESS  OF  DYES 

In  the  case  of  colors  dyed  on  cotton  wash  fabrics  (and  these  are  acquiring 
an  increasing  importance  as  articles  of  apparel),  the  consumer  is  particu- 
larly interested  in  the  fastness  to  washing  in  the  laundry.  As  it  has  become 
the  almost  universal  practice  of  the  modern  laundry  in  addition  to  scouring 
the  goods  with  soap  and  hot  water,  to  whiten  them  by  a  treatment  with  a 
mild  hypochlorite  solution,  it  will  be  seen  that  fastness  in  this  case  requires 
the  dyestuff  to  withstand  the  bleaching  action  of  a  dilute  solution  of  hypo- 
chlorite (known  as  chlorine  bleaching).  There  are  but  very  few  colors 
that  will  withstand  this  influence,  and  the  dyes  have  to  be  selected  with 
great  care. 

An  extended  discussion  of  the  fastness  of  dyes  and  the  qualities  of  fast- 
ness required  for  different  classes  of  material  will  be  taken  up  in  a  later 
chapter;  it  will  suffice  at  this  point  to  take  up  the  more  simple  tests  to 
ascertain  the  more  common  qualities  of  fastness,  and  this  is  most  effi- 
ciently done  by  carrying  out  the  practical  tests  on  various  dyed  colors. 

4.  Experimental.  Exp.  74.  Fastness  to  Light. — For  this  test  (and  those  succeed- 
ing) use  five  of  the  skeins  dyed  in  the  preceding  chapter.  Cut  off  a  sample  of  the  dyed 
skein  about  3  ins.  in  length  and  place  it  in  an  exposure  board,  arranging  it  in  such  a  man- 
ner that  one-half  of  the  sample  is  exposed  to  the  light,  while  the  other  half  is  protected. 
Hang  the  exposure  board  on  the  inside  of  a  window  facing  the  south  in  order  to  obtain 
as  much  sunlight  as  possible.  Allow  the  exposure  to  continue  for  one  week,  at  the 
end  of  which  time  examine  the  sample  for  fading.  If  the  color  shows  any  perceptible 
alteration,  it  must  be  considered  as  not  fast  to  light.  If  no  fading  is  observed,  the  expo- 
sure should  be  continued  for  three  weeks  more.  The  sample  is  now  examined  a  second 
time,  and  if  any  fading  is  apparent,  the  sample  is  removed  and  classified  as  moderately 
fast.  If  no  fading  is  apparent  the  sample  may  be  classified  as  quite  fast  to  light.  The 
degrees  of  fastness  to  light  may  also  be  classified  numerically  as  follows: 

1.  Not  faded  in  four  weeks'  exposure. 

2.  Not  faded  in  one  week's  exposure. 

3.  Faded  by  one  week's  exposure. 

Exp.  75.  Fastness  to  Washing. — This  is  to  represent  the  fastness  of  the  color  to 
scouring  with  soap.  Take  five  or  six  strands  of  the  dyed  yarn  to  be  tested  and  plait  it 
with  a  similar  amount  of  white  woolen  and  white  cotton  strands,  so  as  to  make  up  a 
small  test  sample  about  4  ins.  in  length.  This  sample  is  then  steeped  in  a  soap  solution 
containing  5  grams  of  soap  per  liter.  About  50  cc.  of  the  solution  will  be  required  for 
each  test  and  not  more  than  one  sample  should  be  scoured  in  the  same  liquor.  Have  the 
temperature  of  the  soap  solution  at  140°  F.,  and  wash  the  sample  thoroughly  by  rubbing 
with  the  hands  in  the  same  manner  as  if  the  sample  were  dirty  and  one  was  trying  to 
clean  it.  Use  every  precaution  of  cleanliness  in  order  to  prevent  the  sample  from  becom- 
ing stained  with  any  other  color.  Then  wash  well  in  fresh  warm  water,  and  dry.  Note 
if  this  treatment  has  caused  the  color  to  bleed  into  either  the  white  wool  or  cotton 
with  which  the  colored  yarn  is  plaited,  also  if  any  of  the  color  runs  into  the  soap  liquor, 
and  after  drying  compare  the  sample  with  the  original  color  and  note  if  it  has  under- 
gone any  alteration. 

Exp.  76.  Fastness  to  Fulling  or  Milling. — Plait  together  a  small  test  sample  about 
4  ins.  in  length,  using  several  strands  of  the  dyed  yarn  and  some  strands  of  white  woolen 
yarn.     Work  the  sample  so  prepared  in  about  50  cc.  of  a  solution  containing  5  grams  of 


METHODS  OF  TESTING   FASTNESS 


241 


soap  and  2  grams  of  soda  ash  per  liter  at  a  temj)erature  of  140°  F.  Rub  the  sample 
vigorously  between  the  hands  or  between  two  pieces  of  wood  in  order  to  felt  the  fibers 
together  and  so  imitate  the  action  of  fulling.  After  the  fibers  have  been  well  felted 
together,  wash  the  sample  in  fresh  warm  water,  and  dry.  Note  if  the  color  has  bled 
into  the  white  wool  or  into  the  soap  liquor;  also  compare  the  tested  sami)le  with  the 
original  color  and  note  if  it  has  undergone  any  alteration.  The  fulling  test  is  only 
applicable  to  dyeings  on  wool. 

Exp.  77.  Fastness  to  Water. — This  test  is  more  especially  applied  to  dyeings  on 
silk  and  cotton  yarns,  and  is  to  represent  particularly  fastness  to  rain.  Plait  together 
a  small  test  sample  about  4  ins.  in  length,  using  strands  of  the  dyed  yarn  with  similar 
amounts  of  white  silk  and  white  cotton  yarns.  Steep  this  sample  in  distilled  water  for 
twelve  hours  (overnight),  then  squeeze  out  and  dry.  Note  if  the  color  has  bled  into 
either  of  the  white  yarns  or  into  the  steeping  water. 


Fig.  150. — Machine  for  Dyeing,  Bleaching  or  Washing  Skeins  Tied  in  Long  Chains. 


Exp.  78.  Fastness  to  Perspiration. — This  is  required  of  all  clothing  material 
intended  for  wear  next  to  the  skin;  also  for  materials  for  making  horse-blankets,  etc. 
The  action  of  perspiration  is  an  acid  one,  and  is  said  to  be  best  represented  chemically 
by  the  action  of  acetic  or  lactic  acid  on  the  color.  Plait  a  few  strands  of  the  dyed  yarn 
with  strands  of  white  wool  and  cotton  yarns  in  the  usual  manner,  and  steep  for  one  hour 
in  about  50  cc.  of  a  solution  containing  100  cc.  of  lactic  acid  (22  per  cent)  per  liter  at  the 
ordinary  temperature.  Then  squeeze,  wash  and  dry.  Note  if  the  color  has  bled  into 
either  of  the  white  yarns  or  if  the  color  has  suffered  any  change  from  the  original. 

Exp.  79.  Fastness  to  Carbonizing. — The  carbonizing  process  is  the  treatment  of 
woolen  material  with  acid  and  then  drying  for  the  purpose  of  decomposing  any  vegetable 
matter  present.  It  is  especially  used  in  connection  with  shoddy,  though  it  is  also  at 
times  employed  on  woolen  piece-goods  to  remove  specks  of  vegetable  matter  in  the  fin- 
ished cloth.  Take  a  small  sample  of  the  dyed  woolen  skein  and  steep  it  for  fifteen  min- 
utes in  a  solution  of  sulphuric  acid  at  4°  Tw.  and  at  a  temperature  of  140°  F.  Squeeze, 
and  dry  without  washing,  then  wash  well  and  dry  again.     Note  if  the  color  has  under- 


242         STRIPPING  OF  COLORS;  TESTING  THE  FASTNESS  OF  DYES 

gone  any  alteration  by  tliis  treatment.     This  test  is  only  applicable  to  dyed  woolen 
materials. 

Exp.  80.  Fastness  to  Cross-Dyeing. — By  cro.s.s-dyeing  is  meant  the  dyeing  of  pieces 
containing  white  wool  woven  with  dyed  cotton  yarn;  the  wool  being  dyed  in  a  boiling 
acid  bath,  the  dyed  cotton  must  not  be  changed  by  the  process.  Make  a  small  plaited 
sample  of  strands  of  the  dyed  cotton  yarn  with  strands  of  white  woolen  yarn  and  boil 
the  sample  so  prei)ared  for  fifteen  minutes  in  about  50  cc.  of  a  solution  containing  1  cc. 
of  concentrated  sulphuric  acid  and  2  grams  of  glaubersalt  per  liter;  wash  well,  and  dry. 


^j^ma^ 


Fig.  151. — Beam  Dyeing  Machine  for  Warps.     (Columbus  Truck  and  Supply 

Manufacturing  Co.) 


Note  if  the  color  has  undergone  any  alteration  or  if  it  has  bled  into  the  white  3'arn. 
This  test  is  api)lied  onl}'  to  c(jtton  dj-eings. 

Exp.  81.  Fastness  to  Stoving. — Sometimes  it  is  necessary  to  bleach  woolen  pieces 
containing  white  and  colored  j^arns  woven  together  in  order  to  clear  up  the  white  yams. 
This  bleaching  is  done  with  sulphur  dioxide  (fumes  from  burning  sulphur)  as  a  rule,  and 
the  process  is  known  as  "  stoving."  Take  a  small  sample  of  the  dyed  woolen  yarn, 
moisten  with  water,  and  hang  it  for  six  hours  in  a  closed  compartment  containing 
sulphurous  acid  gas.  Note  if  the  color  has  undergone  any  alteration.  This  test  is 
applied  only  to  dyed  woolen  materials. 

Exp.  82.  Fastness  to  Chloring. — Cotton  pieces  containing  white  and  dyed  yarns 
woven  together  sometimes  rcfiuire  the  bleaching  of  the  white  after  being  woven.  Towel- 
ing with  colored  borders  is  a  good  example  of  this  class  of  material.     The  dyed  colors 


METHODS  OF  TESTING   FASTNESS 


243 


must  therefore  stand  a  treatment  with  chloride  of  lime  solution,  and  this  is  known  as 
"  chloring."  Take  a  sample  of  the  dyed  cotton  skein  and  steep  for  one-half  hour  in  a 
cold  solution  of  chloride  of  lime  at  ^°  Tw.,  rinse  off  and  pass  through  water  slightly- 
acidulated  with  suljihuric  acid.  Finally  wash  well  and  dry.  Note  if  this  treatment  has 
caused  any  change  in  the  color. 

Exp,  83.  Fastness  to  Crocking  or  Rubbing.  —By  tlxis  is  meant  that  the  dyed  mate- 
rial should  not  stain  white  cloth  when  rubbed  against  it.  Well-dyed  material  should 
seldom  show  this  defect,  although  plush  or  pile  fabrics  sometimes  rub  considerably. 
If  the  washing  of  the  material  after  dyeing  has  not  been  sufficiently  thorough,  so  as  to 
remove  aU  particles  of  unfixed  dyestuff,  the  color  afterwards  is  liable  to  rub.  This 
fastness  is  applicable  to  all  classes  of  dyeing.  Carry  out  the  test  by  rubbing  a  dry  sam- 
ple of  the  dyed  yarn  vigorously  on  a  piece  of  white  calico  and  noting  if  it  causes  any  smut 
on  the  white  cloth. 

The  foregoing  tests  for  fastness  of  dyed  colors  represent  the  principal 
requirements  to  be  ordinarilj^  met  with.  A  careful  study  of  the  results  of 
these  tests  will  serve  to  show  that  fastness  to  any  test,  as  well  as  the  degree 
of  that  fastness,  is  not  necessarily  determined  by  the  general  class  to  which 
a  dyestuff  belongs,  but  is  rather  a  particular  property  of  the  individual 
dj'estuff.  Furthermore,  it  is  to  be  borne  in  mind  that  the  requirements  for 
fastness  of  colors  are  largely  to  be  determined  by  the  particular  use  to 
which  the  dyed  material  is  to  be  put,  and  an  intelligent  discrimination  in 
the  selection  of  dyes  to  be  used  should  be  made  with  this  in  view.  A  more 
extensive  discussion  of  the  fastness  of  dyed  colors  on  various  materials 
will  be  taken  up  in  a  succeeding  chapter,  after  the  various  methods  of  dyeing 
have  been  more  thoroughly  studied. 

Tabulation  of  Results  of  Tests 

Make  records  of  the  results  of  the  various  tests  in  the  following  manner,  employing 
five  different  samples  for  the  respective  tests  such  as  have  been  dyed  as  described. 
The  tested  samples  should  be  preserved  in  a  sample  book  for  future  reference. 


FASTNESS   TO   LIGHT 


No. 

Dyestuff. 

Fiber. 

Fading  observed 
in 

Fastness. 

One 
week. 

Four 
weeks. 

244         STRIPPING  OF  COLORS;  TESTING  THE  FASTNESS  OF  DYES 

FASTNESS    TO    WASHING 


Dycstuff. 

Fiber. 

Stains. 

No. 

Soap 
li<|uor. 

White 
wool. 

White 
cotton. 

FASTNESS    TO    FULLING 


Fiber. 

Stains. 

Change  in 

No. 

Dycstuff. 

Soap 
liquor. 

White 
wool. 

color. 

FASTNESS   TO    WATER 


Dypstuff. 

Fiber. 

Stains. 

No. 

White 
cotton. 

White 
silk. 

Water. 

TABULATION    OF   TESTS 
FASTNESS    TO    PERSPIRATION 


245 


DyostvifT. 

Fil^or. 

Stains. 

Change  in 

No. 

White 
wool. 

VVliito 
cotton. 

color. 

FASTNESS   TO    CARBONIZING 


No. 


Dyestuff. 


Alteration  in  color. 


FASTNESS   TO    CROSS-DYEING 


No. 

Dyestu.T. 

Alteration  in  color. 

Bleeding  into  white. 

24G         STRIPPING  OF  COLORS;  TESTING  THE  FASTNESS  OF  DYES 

FASTNESS   TO    STOVING 


No. 

Dyestuff. 

Alteration  in  color. 

FASTNESS    TO    CIILORING 


No. 

Dyosfuff.                                                             Alteration  in  color. 

FASTNESS    TO    CROCKING 


No. 

Dyostuff. 

Fiber. 

Color  rubbing  on  white. 

CHAPTER  X 
APPLICATION   OF  BASIC   DYES 

1.  Characteristics  of  the  Basic  Dyes.— The  basic  dyes  are  mostly 
employed  in  the  form  of  their  salts,  and  in  the  dyebath  these  salts  are 
apparently  dissociated  into  the  dyebase  and  the  acid.*  In  the  dyeing 
operation,  the  acid  is  left  in  the  bath  while  the  dye  base  combines  with  the 
fiber  (in  the  case  of  wool  or  silk)  or  with  the  acid  mordant  (in  the  case  of 
cotton) . 

Like  the  acid  dyes,  the  basic  dyes  are  to  be  found  represented  in  a  num- 
ber of  different  chemical  groups  of  dyestuffs.  The  principal  basic  dyes, 
however,  are  derivatives  of  triphenylmethane,  as  this  group  furnishes 
dyes  having  the  most  beauty,  intensity,  and  brightness,  though  they  do  not, 
as  a  rule,  possess  any  remarkable  fastness.  Some  of  the  chief  representa- 
tives of  this  group  are  Magenta  (Fuchsine),  Methyl  Violet,  and  Mala- 
chite Green.  Notwithstanding  their  lack  of  fastness  they  are  staple  dye- 
stuffs  and  largely  used  for  many  purposes  on  account  of  their  great  bril- 
liancy and  purity  of  tone.  There  are  also  a  number  of  basic  dyes  to  be 
found  among  the  azine  derivatives,  such  as  Safranine  and  Induline. 
Phosphine  and  Acridine  Orange  are  acridine  derivatives,  while  Methylene 
Blue  and  Thioflavine  both  have  sulphur  as  a  substantial  constituent,  the 
one  being  a  thiazine  and  the  other  a  thiazol  derivative.  There  are  some 
basic  dyes  also  to  be  found  among  the  azo  colors,  such  as  Bismarck  Brown 
and  Chiysoidine;  these,  however,  are  also  characterized  by  lack  of  fastness. 

Nearly  all  the  basic  dyes  may  be  converted  into  colorless  derivatives  by 
the  action  of  strong  reducing  agents  (such  as  zinc  and  hydrochloric  acid). 
These  colorless  bodies  are  known  as  leuco-compounds;  and  in  most  cases 
are  readily  converted  into  the  dyestuff  again  by  simple  oxidation  (even 
by  action  of  atmospheric  oxygen).  Certain  of  the  basic  colors,  however, 
such  as  Indoine,  though  reduced  to  leuco-compounds,  will  not  form  the 
original  dye  again  on  oxidation. 

*  The  commercial  form  of  basic  dyes  is  usually  the  chloride,  though  sometimes  the 
ccetate,  oxalate,  sulphate,  or  even  nitrate  may  be  used.  In  some  cases  the  dye  con- 
sists of  the  double  salt  of  hydrochloric  acid  and  zinc  chloride.  It  is  very  rarely  that  the 
dye  is  to  be  met  with  in  the  form  of  the  free  base.  Those  basic  dyes  prepared  by  the 
"  melt  "  process  (such  as  Magenta,  Methyl  Violet,  etc.)  arc  usually  in  the  form  of 
crystals,  while  most  others  occur  as  powders. 

247 


248 


APPLICATION  OF  BASIC  DYES 


U^ 


As  a  class,  the  basic  dyes  give  the  most  brilhant  and  intense  colors  of  all 
dyes.  As  a  rule,  they  have  much  greater  tinctorial  power  than  acid  dyes 
of  corresponding  color.  Their  chief  drawback  is  their  lack  of  fastness,* 
especially  to  light  and  washing,  on  w^iich  account  they  must  be  used  with 
discretion  and  their  field  of  application  is  necessarily  limited.' '  Like  most 
other  large  classes  of  (b'cs,  however,  the  fastness  varies  considerably  with 
different  individual  dj'cs.  IMethjdene  Blue  and  Induline,  for  example, 
when  dyed  on  cotton,  show  veiy  considerable  fastness  to  light  and  soaping. 
In  certain  cases  a  dye  may  be  faster  when  d3^ed  on  wool  than  when  used  on 


faf^— ^- 


Fig.  152.— Warp  Dyeing  Machine;  Closed  Type.     (Pornitz.) 


cotton;   as,  for  instance,  with  Magenta.     On  the  other  hand,  in  the  case 
of  Methylene  Blue  and  Safraninc,  the  reverse  is  the  case. 

Historically  considered,  the  basic  dyes  are  the  oldest  of  the  coal-tar 
synthetic  colors.  The  first  was  produced  by  Perkin  in  1856  and  was  known 
as  Perkin's  IMauve.  As  most  of  them  are  made  from  aniline  (or  homo- 
logues  of  aniline  like  toluidine),  they  received  the  general  name  of  "  aniline 
dyes,"  and  this  name  has  still  persisted  in  the  trade  as  inclusive  of  all  coal- 
tar  dyes;  though  at  the  present  time,  of  course,  there  are  a  great  man> 
coal-tar  dyes  not  made  either  directly  or  indirectly  from  aniline,  hence  the 
practice  of  designating  them  all  as  "  aniline  dyes  "  is  both  misleading  and 
erroneous.  Owing  to  the  fact  that  these  early  basic  dyes  were  rather 
fugitive,  it  became  a  popular  impression  that  all  "  aniline  dyes  "  are  defi- 


GENERAL  CHARACTER  OF  BASIC  DYES 


249 


cient  in  fastness  and  arc  far  inferior  to  the  old  natural  dyes.  Strange  to 
say,  this  impression  persists  in  the  popular  mind  even  to  the  present  day, 
though  it  is  a  well-known  fact  easily  demonstrated  by  actual  test,  that  thers 
are  a  great  many  coal-tar  dyes  possessing  qualities  of  fastness  far  surpassing 
those  of  any  of  the  natural  dyes.  In  fact,  one  of  the  chief  reasons  for  the 
decline  in  the  use  of  most  of  the  natural  dyes  is  their  lack  of  ability  to 
meet  the  fastness  requirements  of  the  present-day  colors. 

Though  of  wide  use  and  of  great  value  in  the  early  days  of  synthetic 
dyes,  the  basic  dyes  as  a  class  have  not  the  same  importance  as  formerly. 
The  introduction  of  the  acid  dyes  for  wool  and  silk,  as  well  as  the  sub- 
stantive and  sulphur  dyes  for  cotton  have  displaced  the  basic  colors  to  a 

^1-x  -..^ 


Fig. 


153. — Open  Dyeing  Machine  with  Automatic  Regulating  Arrangement  for  Vacu- 
um, Steam,  or  Compressed  Air,  for  Warps  on  Beams.     (Pornitz.) 


great  extent.  Many  of  these  other  dj-'es  are  much  faster  and  much  cheaper 
than  the  basic  dyes,  and  except  where  great  brilliancy  and  purity  of  tone  is 
desired,  the  basic  dyes  are  not  used.  In  cotton  dyeing,  their  use  is 
restricted  "orTaccount  of  the  expensive  and  complicated  process  of  dyeing, 
three  different  operations  and  baths  Ijcino;  required, — mordanting,  fixing, 
and  dyeing.  The  basic  dyes,  however,  are  still  largely  used  in  calico  print 
Ing  and  tor  tne  production  of  light  tints  and  brilliant  colors  on  silk.  They 
are  also  used  considerably  in  paper  dyeing  and  staining  and  in  the  dyeing 
of  jute. 

2.  The  Use  of  Basic  Dyes  on  Silk. — The  basic  dyes  are  very  largely 
emploj^ed  on  silk,  for  the  silk  fiber  has  a  strong  affinity  for  these  color- 
ing matters,  and  the  methods  of  their  application  are  simple.     Further- 


250  APPLICATION  OF  BASIC  D^^ES 

more,  the  colors  oljtainccl  with  the  basic  ch'es  are  especially  characterized 
In'  depth  and  brilliancy,  factors  which  are  verj^  important  in  dyeing 
silk.  On  account  of  the  strong  affinity  of  Ijasic  colors  for  silk,  it  is  not 
always  wise  to  add  all  of  the  required  dyestuff  at  once  to  the  bath,  but 
in  several  portions  as  the  dyeing  proceeds.  The  basic  colors,  in  fact,  are 
especially  adapted  to  silk  goods  as  it  is  usually  desirable  on  this  fiber  to 
obtain  clear  brilliant  colors  of  pure  tones,  and  also  the  requirements  of 
fastness  to  light  and  waslimg  are  not  so  strict.  Silk_isjisiially-^:ed- with 
the  basic  dj'es  in  a  bath  containing  boiled-off  liquor  "  broken  "  (that  is, 
neutralized)  with  acetic  acid;  entering  the  goods  at  100°  F.,  and  gradually 
raising  to  180°  F.  Instead  of  boiled-off  liquor,  soap  may  be  u-d.  or  it 
ma}'  be  omitted  cntireh',  the  dyebath  simply  being  made'  iip  with  acelic 
acid.  After  d^-eing,  the  silk  is  rinsed  and  brightened  b}-  passing  through 
a  bath  slightly  acidulated  with  acetic  or  tartaric  acid,  squeezing  and 
drying. 

Especial  care  must  be  taken  in  the  solution  of  the  basic  dyes,  for  wheotf 
boiling  water  is  employed  for  this  pin-pose  there  is  liability  of  tarry  matters 
being  formed  by  a  partial  decomposition  of  the  dyestuff.  It  is  best  to  use 
warm  water  acidified  with  acetic  acid.  In  some  cases  the  dyes  are  more 
readily  dissolved  if  a  little  methylated  alcohol  is  added.  Acetin,  which  is  a 
preparation  from  acetic  acid  and  gh'cerin,  is  sometmies  employed  for 
assisting  the  solution  of  basic  dyes.* 

The  basic  dyes  give  good  exhaustion  in  the  dyebath,  and  it  is  seldom 
necessary-  to  employ  standing  baths.  The  temperature  when  d^-eing  basic 
colors  is  seldom  brought  to  ov£r  180°  F..  as  higher  temperatures  may  cause 
decomposition  of  the  dyestuff  (especialh'  noticeable  in  the  case  of  Aura- 
mine  and  Diamond  ]Magenta),  leading  to  the  formation  of  sticky,  insoluble, 
tarrj'  products.  As  the  Ijasic  colors  are  quite  sensitive  to  hard  water,  it  is 
always  necessary  to  correct  such  water  by  the  proper  addition  of  acetic  acid. 

The  basic  colors  are  especially  serviceable  in  the  dyeing  of  weighted  silks 
where  the  weighting  has  been  done  with  tin  salts,  f  An  after-treatment 
with  tannic  acid  and  tartar  emetic  is  generalh'  resorted  to  for  the  purpose 
of  giving  greater  fastness  to  washing,  t 

*  It  has  already  been  remarked  that  in  the  case  of  Auramine,  the  solution  should  not 
be  heated  over  170°  F.,  as  othem'ise  the  d\'e  will  suffer  decomposition  and  a  precipitate 
will  form.  It  is  also  to  be  noted  that  solutions  of  Bismarck  Brown  and  Chrysoidine 
should  not  be  boiled  for  anj'  length  of  time.  In  dissolving  Victoria  Blue  and  Fast  Blue 
for  Cotton,  the  dye  should  be  stirred  up  with  some  acetic  acid;  with  the  cheaper  grades 
of  Magenta,  hydrochloric  acid  should  be  used. 

t  Xo  special  precautions  are  necessary  in  dyeing  tin-weighted  silk  with  ba.sic  dyes 
except  to  give  the  silk  a  warm  wash  before  dyeing  to  remove  any  unfixed  metallic  salt. 
Tin-weighted  silk  which  has  been  long  in  stock  is  liable  to  dj'e  unevenly,  owing  to 
decomposition  of  the  weighting. 

I  Colors  on  silk  are  frequently  required  to  be  fast  to  water  (that  is,  should  not  bleed 


DYEING  BASIC  COLORS  ON  WOOL  251 

The  dyeing  of  weighted  silk  is  done  in  a  boiled-off  hquor  bath  (half 
boiled-off  liquor  and  half  water)  just  broken  with  acetic  acid;  the  goods 
are  entered  at  100°  F.,  and  slowly  brought  to  180°  F.  After  dyeing,  the' 
goods  are  well  rinsed  and  brightened  as  usual  with  acetic  or  tartaric  acid^ 
Some  of  the  basic  dyes  (Ethyl  Green,  Diphene  Blue,  Methyl  Violet)  give 
colors  on  silk  which  have  a  good  fastness  to  water,  but  with  many  of  them, 
the  fastness  in  this  respect  is  not  very  satisfactory,  though  the  fastness 
may  be  much  increased  by  an  after-treatment  with  tannin  and  tartar 
emetic.  The  basic  dyes  having  good  fastness  to  light  on  silk  are  Rhoda- 
mine,  Eth}^  Green,  Malachite  Green,  and  Diphene  Blue.  On  tin-weighted 
silk,  Methylene  Blue  and  Methyl  Violet  (R  brands),  also  have  good  fast- 
ness to  light. 

3.  Use  of  Basic  Dyes  for  Wool. — The  basic  dyes  *  at  the  present  time 
do  not  find  much  application  on  woolen  goods,  as  better  results  are  gener- 
ally to  be  obtained  by  the  use  of  acid_colors.  f  In  former  years,  the 
basic  colors  were  much  more  used  for  wool  than  they  are  now;  but  by 
treatment  with  sulphuric  acid  many  of  the  basic  dyes  can  be  converted 
into  corresponding  acid  derivatives  which  are  used  instead.  Thus,  Magenta 
gives  Acid  Magenta,  Methyl  Violet  is  converted  into  Acid  Violet,  etc.  The 
affinity  of  basic  dyes  for  wool  is  very  great,  hence  they  are  liable  to  dye  up 
uneven  unless  proper  precautions  are  taken,  such  as  adding  the  dye  solution 
to  the  bath  in  several  portions,  starting  the  dyeing  at  a  low  temperature, 
adding  some  acetic  acid  or  alum  to  the  bath,  etc.  Rhodamine  is  quite 
extensively  used  on  wool  for  the  production  of  bright  pink  colors  ;t 
the  dyed  material  may  be  bleached  with  sulphurous  acid  gas,  which  con- 
when  steeped  in  water  overnight).  Most  basic  dyes  will  not  stand  this  test,  though 
their  fastness  in  this  respect  may  be  considerably  improved  by  the  following  after- 
treatment.  The  dyed  silk  is  worked  for  fifteen  minutes  at  140°  F.  in  a  bath  containing 
5  to  10  per  cent  tannic  acid,  then  steeped  overnight.  Squeeze  and  work  in  a  bath  con- 
taining 2 1  to  5  per  cent  tartar.  Then  wash  well  and  dry.  Allowance  must  be  made  of 
the  fact  that  the  treatments  somewhat  dull  the  tone  of  the  color. 

*  Victoria  Blue  is  still  used  considerably  in  wool  dyeing  notwithstanding  its  lack  of 
fastness  to  light.  It  gives  brilliant  sky  to  royal  blues  of  good  fastness  to  washing  and 
fulling  and  surpasses  all  other  wool  blues  for  brilliancy.  It  is  usually  dyed,  however, 
in  a  manner  similar  to  that  of  acid  dyes. 

t  Malachite  Green  (and  also  Ethyl  Green),  though  seldom  used  at  the  present  time 
for  dyeing  wool,  requires  a  special  method  of  application  to  this  fiber.  Previous  to 
dyeing  the  wool  is  treated  with  what  is  known  as  the  sulphur  mordant  in  the  following 
manner:  For  10  lbs.  of  wool,  use  a  bath  containing  1  lb.  of  sodium  hyposulphite,  1  lb. 
of  alum  and  6  ozs.  of  sulphuric  acid;  enter  the  goods  at  100°  F.,  gradually  raise  to  180°  F., 
and  work  at  that  temperature  for  one  hour;  rinse  well,  and  dye  in  a  bath  containing 
3  ozs.  of  sodium  acetate,  and  have  the  temperature  not  to  exceed  180°  F. 

I  Rhodamine  is  dyed  on  wool  in  a  bath  containing  either  5  per  cent  of  acetic  acid  or 
20  per  cent  of  glaubersalt  and  1  to  3  per  cent  of  sodium  bisulphate.  Victoria  Blue  is 
also  dyed  in  the  same  manner.  On  this  account  manj^  dyers  are  liable  to  classify  these 
two  colors  among  the  acid  dyes. 


252  APPLICATION  OF  BASIC  DYES 

sklerably  brightens  up  tho  color  and  also  gives  it  greater  fastness  to  light."' 
Rhoclauiinc  pinks  are  sufficiently  fast  to  washing  for  most  purposes. 
y^f^XoYs  obtained  with  basic  dyes  on  wool  are  as  a  rule  not  very  fast  to 
Tight  or  washing,  and  also  exhibit  a  tendency  to  crock.  The  basic  dj-es  are 
used  much  more  on  cotton  than  Xh^y  are  on  wool,  though  even  here  their 
importance  has  been  considerably  diminished  since  the  introduction  of  the 
direct  cotton  dyes.  Where  great  depth  and  brilliancy  of  shade,  however, 
are  required,  they  are  still  used,  for  they  far  surpass  the  substantive  dj'es  in 
these  respects.  In  this  connection,  it  may  be  mentioned  that  the  basic 
dyes  are  considerably  used  for  topping  both  the  substantive  and  the  sul- 
phur dyes,  for  the  purpose  of  brightening  the  tone  (see  page  263).  The 
green  obtained,  for  instance,  with  a  Direct  Cotton  Green  or  a  Sulphur  Green 
is  comparativeh^  dull,  but  if  topped  in  a  separate  dyebath  with  even  a  very 
small  proportion  of  Malachite  Green,  the  tone  of  the  resulting  green  color 
is  wonderfully  brightened.  Dye  spots,  consisting  of  uneven  streaks  or 
spots,  often  occur  when  d3'eing  with  basic  colors,  caused  by  precipitation 
of  the  color-base  in  the  dyebath  either  by  the  use  of  hard  water  or  by 
imperfect  solution. 

4.  Experimental.  Exp.  84.  Dyeing  Silk  with  Basic  Colors. — Dj'e  a  test  skein  of 
silk  in  a  bath  containing  150  cc.  of  water,  25  cc.  of  boiled-off  liquor,  and  2  per  cent  of 
Magenta;  enter  the  skein  at  120°  F.,  and  gradually  bring  to  180°  F.,  and  dye  at  that 
temperature  for  one-half  hour,  then  wash  well  and  dr\-.  Silk,  like  wool,  has  a  direct 
affinity  for  the  basic  colors. 

Exp.  85.  Dyeing  Silk  in  a  Neutral  Soap  Bath. — Prepare  a  bath  containing  1.50  cc.  of 
water,  5  per  cent  of  soap  (which  should  lie  a  neutral,  olive  oil  soap).t  Work  the  test 
skein  of  silk  in  this  bath  for  a  short  time  at  140°  F.,  then  add  2  per  cent  of  Methylene 
Blue  solution  in  several  portions,  at  the  same  time  raising  the  temperature  of  the  bath  to 
180°  F.     Continue  at  this  temperature  for  fifteen  minutes,  then  add  sufficient  acetic 

*  Besides  Rhodamine  there  maj-  also  be  used  such  dyes  as  Auramine,  Methyl  Violet, 
\'ictoria  Blue,  Nile  Blue,  and  Light  Green  SF.  The  dj-eing  is  usually  conducted  in  a 
lukewarm  soap  bath  (containing  1  oz.  of  neutral  soap  per  gallon  of  soft  water),  and  after 
the  goods  are  hydro-extracted  they  are  bleached  with  sulphurous  acid  gas  in  the  ordinary 
'■  stoving  "  chamber.  For  pale,  delicate  shades  on  yarns,  the  bleaching  operation  may 
be  carried  out  directly  in  the  dyebath  itself  by  the  use  of  sodium  bisulphite  solution. 
About  15  per  cent  of  the  latter  (32°  Tw.)  is  added  to  the  dj-ebath,  with  10  per  cent  of 
glaubersalt  and  2  per  cent  of  sulphuric  acid.  The  dyeing  is  started  lukewarm  and 
brought  to  the  boil.  The  same  d\-estuffs  mentioned  above  maj'  be  used,  and  in  addition 
Palatine  Scarlet,  Tartrazine,  and  Acid  Violet.  The  bath  should  not  be  boiled  for  any 
length  of  time  or  the  colors  will  be  dulled. 

t  When  dyeing  souple  or  ecru  silk,  a  soap  bath  cannot  be  used,  as  this  would  cause 
a  considerable  portion  of  the  silk-glue  to  be  removed  and  thus  the  silk  would  lose  in 
weight.  In  such  cases,  bast  soap  (boiled-off  liquor)  only  can  be  used  in  the  dyebath. 
It  has  been  proposed,  however,  to  treat  the  souple  or  ecru  silk  with  a  dilute  solution  of 
formaldehyde,  which  has  the  effect  of  rendering  the  silk-glue  insoluble.  It  is  said  that 
silk  treated  in  this  manner  can  then  be  dyed  in  hot  soap  solutions  without  any  material 
loss  of  silk-glue. 


EXPERIMENTAL  STUDIES 


253 


acid  to  sUghtly  acidulate  the  bath,  and  continue  dyeing  for  fifteen  minutes  longer. 
Then  wash  well  and  brighten  with  acetic  acid  in  the  manner  given  in  Exp.  59.  Dye  a 
second  sample  of  silk  in  the  same  manner  with  2  per  cent  of  Rhodamine. 

Exp.  86.     After-treatment  of  Basic  Dyes  on  Silk  with  Tannin. — Dye  a  test  skein  of 
silk  with  2  per  cent  of  Methyl  Violet  as  described  in  Exp.  84;  wash  well  and  pass  into 


Fig.  154. — Beam  Dyeing  Machine  for  Warps.     (Haubold.) 


a  fresh  bath  containing  100  cc.  of  water  and  1  gram  of  tannic  acid;  work  for  twenty 
minutes  at  180°  F.,  then  sink  under  the  liquor  and  leave  for  one-half  hour  without  fur- 
ther heating.  Squeeze  out  the  excess  of  liquor  and  work  in  a  fresh  bath  containing  100 
cc.  of  water  and  0.5  gram  tartar  emetic  at  a  temperature  of  140°  F.  for  twenty  minutes. 
Wash  well  and  brighten  with  acetic  acid  as  usual.  Dye  a  second  skein  of  silk  in  the  same 
manner  with  2  per  cent  of  Malachite  Green. 


254  APPLICATION  OF  BASIC  DYES 

Exp.  87.  General  Method  of  Applying  Basic  Dyes  to  Wool. — Basic  colors  are  usually 
dyed  on  wool  in  neutral  or  slightly  acid  baths.  Dye  a  skein  of  woolen  yarn  in  a  bath 
containing  300  cc.  of  water,  2  per  cent  of  acetic  acid,  10  per  cent  of  glaubersalt,  and  1 
per  cent  of  Methylene  Blue;  enter  at  100°  F.,  gradually  raise  to  180°  F.,  and  dye  at 
that  temperature  for  one-half  hour.  Dye  another  skein  of  woolen  j^arn  in  a  similar 
bath  containing  10  per  cent  of  glaubersalt  and  1  ])cr  cent  of  Mcthj-Icne  Blue  in  the  same 
manner,  and  note  that  the  dyestuff  is  absorbed  more  rapidly.  The  function  of  the  acid 
is  to  retard  the  dyeing,  and  so  assist  in  the  even  distribution  and  thorough  penetration 
of  the  color.  If  the  bath  in  the  first  case  does  not  exhaust  completely,  lift  the  skein  and 
add  4  per  cent  of  borax  and  continue  dyeing  for  fifteen  minutes.  The  borax  is  a  mild 
alkali,  and  is  added  for  the  purpose  of  neutralizing  the  acid  in  the  bath  and  so  per- 
mitting the  complete  exhaustion  of  the  dyestuff.  Acetic  acid  is  better  to  use  in  dyeing 
basic  colors  than  sulphuric  acid,  as  the  former  is  volatile,  and  as  the  temperature  of  the 
dyebath  rises  the  acidity  becomes  lessened  and  consequently  the  exhaustion  is  better. 

Exp.  88.  Showing  Effect  of  Hard  Water  in  Dyeing  Basic  Dyes. — Prepare  two  dj'e- 
baths  with  j  per  cent  of  Magenta;  in  the  one  case  using  distilled  water  and  in  the  other 
ordinary  tap  water.  Dye  a  .skein  of  wool  in  each  of  these  baths.  Both  baths  should  be 
entirely  exhausted.  Note  that  the  color  is  heavier  on  the  first  skein  than  on  the  second. 
Add  a  small  quantity  of  sulphuric  acid  to  each  bath;  the  bath  with  distilled  water  will 
remain  colorless,  showing  that  no  dye  has  been  left.  But  the  bath  with  hard  water  will 
become  colored  pink,  which  is  due  to  the  fact  that  part  of  the  dyestuff  was  precipitated 
as  the  leu  co-base,  which  on  the  addition  of  the  acid  becomes  converted  again  into  the 
colored  salt  and  goes  into  solution.  On  this  account,  it  is  frequently  recommended 
in  dyeing  wool  or  silk  with  basic  dyes  to  use  a  small  amount  of  acid  in  the  bath.  An 
excess  of  acid,  however,  should  be  avoided,  as  it  will  decrease  the  exhaustion  of  the  bath. 

Exp.  89.  Showing  the  Greater  Coloring  Power  of  Basic  Dyes  over  Acid  Dyes. — 
Dye  a  skein  of  woolen  yarn  in  a  bath  containing  300  cc.  of  water,  10  per  cent  of  glauber- 
salt, 4  per  cent  of  sulphuric  acid,  and  2  per  cent  of  Acid  Magenta;  enter  at  140°  F., 
gradually  raise  to  the  boil  and  dye  at  that  temperature  for  one-half  hour.  Dye  a  second 
skein  in  a  bath  containing  300  cc.  of  water,  10  per  cent  of  glaubersalt,  and  2  per  cent  of 
Magenta;  dye  for  the  same  length  of  time  and  under  similar  conditions  as  above. 
After  dyeing,  wash  and  dry  the  two  skeins.  Note  the  depth  of  color  on  each,  and  it 
will  be  found  that  the  skein  dyed  with  the  acid  color  is  considerablj''  lighter  than  the 
one  dyed  with  the  basic  color. 

Exp.  90.  Use  of  a  Neutral  Bath. — Most  basic  dyes  will  dye  fairly  well  on  wool  from 
neutral  baths,  though  the  water  u.sed  should  be  soft,  or,  if  hard,  should  be  corrected  by 
the  addition  of  acetic  acid.  For  each  degree  of  hardness  of  the  water  about  f  oz.  of 
acetic  acid  should  be  added  per  100  gallons  of  water.  Or  perhaps  a  more  convenient 
method  is  to  add  acetic  acid  to  the  water  of  the  dyebath  until  it  shows  a  faint  acid  reac- 
tion with  litmus  paper  (turning  blue  litmus  paper  red).  The  color  is  more  apt  to  be 
uneven  from  neutral  baths  than  from  those  containing  acid.  Dye  a  skein  of  woolen 
yarn  in  a  bath  containing  300  cc.  of  water,  10  per  cent  of  glaubersalt,  and  1  per  cent  of 
Rhodamine;  enter  at  100°  F.,  gradually  bring  to  180°  F.,  and  continue  at  that  tempera- 
ture for  one-half  hour,    Wash  and  dry. 


CHAPTER  XI 
BASIC  DYES  ON  COTTON 

1.  The  Use  of  Basic  Colors  on  Cotton. — Though  the  basic  dyes  possess 
a  strong  affinity  for  the  animal  fibers,  and  may  be  dyed  on  these  in  a  neu- 
tral bath  without  any  other  addition  than  the  dyestuff  itself,  cotton  (and 
the  vegetal^le  fiberi^  in  general)  possesses  but  a  very  slight  attraction  for 
this  class  of  dy€^uffs.'/A  few  of  the  basic  dyes,  such  as  Magenta,  Chry- 
soidine,  Bismarck  Brown,  and  Methylene  Blue,  will  be  absorbed  to  a  cer- 
tain extent  by  the  cotton  fiber;  but  most  of  the  color  may  be  washed  out 
with  cold  water,  and  almost  entirely  removed  with  a  warm  soap  solution. 
An  exception  must  be  mentioned  of  certain  dyes  among  the  class  of  water- 
soluble  indulines,  such  as  Indazine,  Indamine  Blue,  Toluylene  Blue, 
Nigramine,  New  Gray,  Methylene  Gray  and  Indoine  Blue,  which  give 
dyeings  of  considerable  fastness  on  cotton  with  no  other  addition  to  the 
dyebath  than  sodium  acetate.*    ^^ 

In  order  to  dye  cotton  with  the  basic  dyes  it  is  customary  to 
previously  mordant  the-jnaterial  with  tannin  and  antimony.  It  may 
be  considered  thata  tannate  of  antimony  is  precipitated  within  the  fiber 
which  exhibits  a  strong  affinity  for  the  basic  dyes  and  gives  with  them 
an  insoluble  color-lake.  The  affinity  between  the  dyestuff  and  the 
antimony  tannate  is  usually  so  great  that  it  is  difficult  to  obtain  uniform 
colors  injhedyfiing,  as,  for  instance,  with  Methylene  Blue,  Nigramine, 
"etcl^  On  this  account  it  is  advised  not  to  add  all  of  the  dyestuff  to  the 
bath  at  once,  but  to  dissolve  it  up  and  add  the  solution  in  several  por- 
tions. Furthermore,  it  is  best  to  start  the  dyeing  at  a  low  temperature 
and  not  to  raise  the  temperature  too  rapidlyi-^^s  a  rule,  it  will  not  be 
necessary  to  bring  the  bath  to  the  boil,  as  the  dyeing  is  usually  complete 
at  about  180°  F. 

In  the  dyeing  of  basic  colors  on  cotton  the  tannin  mordant  may  be^ 
applied  in  one  of  two  ways:  (1)  steeping  the  cotton  in  the  solution  of  tannin 
for  a  comparatively  long  time,  then  squeezing  and  fixing  with  tartar 
emetic  or  other  suitable  salt;    (2)  padding  with  the  solution  of  tannin, 

*  Rather  full  and  fast  colors  may  be  obtained  in  this  manner  if  the  dyeing  is  given 
an  after-treatment  with  chrome. 

255 


^ 


256  BASIC  DYES  ON  COTTON 

which  consists  in  impregnating  the  cotton  with  a  strong  solution  for  a 
short  time,  then  squeezing  and  drying  or  fixing  first  with  an  antimony- 
salt.  The  first  method  is  that  usually  employed  for  yarn  dyeing,  while 
the  padding  method  is  largely  used  in  cloth  dyeing  and  also  for  the  produc- 
tion of  mordanted  cloth  for  purposes  of  printing.  In  the  steeping  process 
it  has  been  the  custom  to  lay  the  yarn  *  down  in  the  tannin  li(]Uor  over- 
night, starting  at  a  temperature  somewhat  under  the  boiling  point  and 
allowing  to  cool;  it  is  a  question  as  to  whether  the  cotton  will  absorb 
much  more  tannin  in  this  time  than  in  a  cou]ole  of  hours.  From  experi- 
ments which  have  been  performed  on  this  point  it  would  seem  that  by  enter- 
ing the  cotton  at  a  temperature  just  under  the  boil  and  allowing  it  to  steep 
in  the  cooling  liquor  for  about  2  hours  it  will  absorb  about  as  much  tannin 
as  it  would  if  the  steeping  was  continucnl  for  ten  to  twelve  hours,  f  It  is 
best  to  start  the  steeping  at  a  temperature  near  the  boiling  point,  chiefly 
for  the  purpose  of  driving  out  air  bubbles  from  the  fiber  and  causing  better 
penetration  of  the  tannin  solution.  The  higher  temperature  does  not 
appear  to  influence  the  actual  absorption  of  the  tannin  itself  by  the  cotton, 
as  more  is  absorbed  from  a  cooling  bath  than  from  one  in  which  a  high 
temperature  is  maintained. 

The  strength  of  the  tannin  bath  should  be  based  on  the  amount  of 
coloring  matter  to  be  subsequently  used,  it  being  customary  to  take  about 
twice  as  much  tannin  (as  tannic  acid  and  corresponding  amounts  of  tannin 
extracts  in  accordance  with  the  percentage  of  tannic  acid  present)  as  dye- 
stuff;  that  is,  if  a  color  is  to  be  obtained  requiring  about  2  per  cent  of 
dj'estuff,  about  4  per  cent  of  tannin  should  be  used  for  mordanting. 
Where  light  shades  are  being  dyed  it  is  not  customary  to  preserve  the 
tannin  bath,  but  for  dark  heavy  shades,  where  baths  containing  4  to  10 
per  cent  of  tannin  are  being  used,  it  is  best  to  use  the  baths  continuously, 


*  Before  the  3'arn  is  placed  in  the  tannin  bath,  it  is  advisable  first  thoroughly  to  wet 
it  out  in  order  that  the  tannin  may  be  effectiveh'  and  uniformlj-  absorbed.  This  is 
especialh'  true  if  the  tannin  bath  is  not  used  at  the  boil.  If  the  dry  cotton  is  steeped 
in  the  tannin  bath,  it  will  be  found  that  often  spots  and  streaks  will  subsequentl}'  develop 
on  dyeing  due  to  the  lack  of  uniform  mordanting.  In  cases  when  it  may  not  be  con- 
sidered practical  to  boil-out  the  cotton  first,  it  is  advisable  to  add  some  soluble  oil  (such 
as  IMonopol  Oil)  to  the  hot  tannin  bath  (1  pint  of  oil  to  100  gallons).  This  will  cause 
the  cotton  to  wet-out  very  uniformly  in  the  bath  itself  even  at  temperatures  consider- 
ably below  the  boil.  It  is  better,  however,  to  always  enter  the  goods  in  the  boiling  tan- 
nin bath,  work  for  half  an  hour  at  that  temperature  to  ensure  even  penetration  of  the 
goods,  and  then  to  steep  the  cotton  for  two  hours  in  the  cooling  bath.  Under  these 
conditions  the  cotton  will  be  uniformly  mordanted,  and  will  have  absorbed  practically 
its  maximum  amount  of  tannin.  \Yhere  hard-twisted  and  heavy  goods  are  in  question, 
it  is  always  advisable  to  use  some  soluble  oil  in  the  tannin  bath. 

It  has  been  shown  that  cotton  absorbs  tannic  acid  most  readily  at  a  temperature 
of  about  105°  F. 


MORDANTING  WITH  TANNIN 


257 


freshening  the  standing  bath  each  time  with  3  to  4  per  cent  of  tannin.* 
The  amount  of  hquor  used  in  the  mordanting  bath  should  not  be  more 
than  fifteen  to  twenty  times  the  weight  of  the  cotton ;  that  is,  each  pound 
of  cotton  should  have  about  2  gallons  of  water  for  mordanting;  if  a  greater 
amount  of  water  is  used,  the  proportion  of  tannin  absorbed  by  the  fiber 
will  be  lessened  and  a  correspondingly  larger  amount  of  tannin  will  have 
to  be  used. 

The  water  employed  in  the  mordanting  bath  should  be  as  free  from  iron 
as  possible  if  the  tannin  is  to  be  fixed  with  antimony;  for  iron  present  in 
even  a  slight  trace  will  alter  the  color  of  the  dyeing  considerably,  especially 
in  the  case  of  pale  shades.     If  the  water  does  contain  any  iron,  a  small 


Fig.  155. — Dyeing  Machine  for  Yarn  in  Form  of  Spools.      (Erckens  &  Erix.) 

amount  of  hydrochloric  acid  should  be  added  which  will  hold  the  iron  tan 
nate  in  solution  and  prevent  it  from  contaminating  the  fiber.  Hard  water, 
that  is,  a  calcareous  water,  unless  of  very  considerable  hardness,  is  not 
especially  detrimental  for  use  with  tannin;  if  there  is  much  lime  present, 
it  may  result  in  the  precipitation  of  some  of  the  mordant  in  the  form  of 
t annate  of  lime.  Such  water  may  be  best  corrected  by  the  addition  of  suf- 
ficient acetic  acid  to  give  a  slight  acid  reaction  to  the  bath  previous  to  the 
addition  of  the  tannin. 

*  Since  the  tannin  bath  exhausts  but.  very  incompletely,  it  is  nearly  always  the 
practice  in  dyehouses  to  maintain  a  standing  bath.  Usually  about  one-half  the  quan- 
tity of  tannin  used  in  the  first  bath  is  added  for  each  subsequent  lot  of  goods.  In  case 
old  tannin  baths  show  a  tendency  to  ferment,  they  should  be  boiled  up  from  time  to 
time,  or  some  preservative  such  as  salicylic  acid  may  be  added  to  the  solution. 


258  BASIC  DAYS  ON  COTTON 

After  the  steeping  in  the  tannin  is  completed,  the  cotton  should  be  well    i 
squeezed  or  wrung  out  to  remove  the  excess  of  liquor ;  in  practice  this  may  ^ 
be  best  accomplished  by  hydro-extraction.     It  is  not  advisable  to  rinse  ^ 
the  cotton  after  removal  from  the  tannin  bath,  as  this  will  only  result  . 
in  redissolving  some  of  the  absorbed  tannin,  and  the  residual  liquor  in 
the  cotton  will  still  be  a  solution  of  tannin;   so  that  the  rinsing  does  not 
sei-ve  the  purpose  of  removing  such  residual  liquor,  but  only  results  in  the 
lessening  of  the  mordant.     There  does  not  appear  to  be  much  difficulty 
attached  to  the  uneven  squeezing  or  wringing  of  the  mordanted  cotton 
leading  to  uneven  results  in  the  subsequent  dyeing;  probably  if  the  tannin 
through  one  cause  or  another,  is  distributed  very  unevenly  through  the 
cotton,  there  may  result  uneven  dyeing,  yet  under  ordinary  conditions 
particular  caution  does  not  have  to  be  taken  in  the  even  squeezing  of  the 
wet  cotton.*  ^ 

After  the  mordanted  cotton  is  squeezed  the  next  operation  is  to  pass 
through  a  fixing  bath  containing  tartar  emetic  or  other  suitable  salt  of 
antimony.  The  fixing  is  complete  in  from  fifteen  to  thirty  minutes  and  a'  y 
cold  l)ath  is  used ;  the  amount  of  tartar  emetic  necessary  is  about  one-half 
that  of  the  tannin  used;  in  other  words,  it  is  about  equivalent  to  the'^ 
amount  of  dyestuff  to  be  used,  f  For  other  antimony  salts,  corresponding 
amounts  must  be  used.  "{- 

The  reaction  in  the  fixing  bath  consists  of  the  formation  of_antiriiQny  " 
tannatejii_thejfiber,  and  it  should  be  so  adjusted  that  all  of  the  tannin 
present  is  thus  combined;  this  reaction  necessitates,  of  course,  the  libera- 
tion in  the  bath  of  the  acid  previously  combined  with  the  antimony — 
with  tartar  emetic  there  would  be  liberated  tartaric  acid.>^  On  this  account 

*  The  tannin  should  be  fixed  as  soon  as  possible  after  mordanting,  otherwise  the 

tannin  will  drain  more  to  one  part  of  the  goods  than  another  and  result  in  uneven  dyeings. 

t  The  following  table  shows  the  usual  relation  between  dyestuff,  tannin  and  tartar 

emetic. 

Dye  Tannin  Tartar  Emetic 

%  %  % 

0.1  \  \ 

4  .  i  2 

1  11  3 

3  ^2  4 

1  3  U 

\\  5  2\ 

2  8  4 

X  A  process  has  lately  been  devised  relating  to  the  better  fixation  of  the  tannin  by 
tartar  emetic  when  mordanting  cotton  for  dyeing  with  basic  colors.  In  this  connection 
a  study  has  been  made  of  the  projier  conditions  for  the  most  economical  fixation  of 
the  tannin.  It  has  been  demonstrated  that  the  fixation  of  the  tannin  by  the  tartar 
emetic  is  not  effected  as  rapidly  as  has  generally  been  supposed.  The  maximum  degree 
of  fixation  is  obtained  by  a  treatment  of  about  forty  minutes'  duration  in  the  tartj.r 
emetic  bath;  if  the  treatment  is  continued  for  a  longer  period  than  this,  however,  the 
amount  of  tannin  fixed  is  diminished  rather  than  increased.     But  the  new  process  to 


FIXING  WITH  TARTAR  EMETIC  259 

when  using  the  fixing  hquor  as  a  standing  bath,  it  will  be  necessary  to 
add  sufficient  soda  ash  from  time  to  time  to  neutralize  the  acidity,* 
otherwise  the  tannate  of  antimony  will  be  dissolved  from  the  fiber.  When 
the  fixation  of  the  tannin  mordant  is  completed  the  cotton  must  be  thor- 
oughly washed  for  the  purpose  of  removing  all  uncombined  tartar  emetic 
or  tannin;  if  excess  of  either  of  these  is  present  in  the  fiber  when  it  is 
passed  into  the  dyebath  it  will  result  in  the  loss  of  coloring  matter  and 
probably  lead  to  streaked  and  imperfect  dyeing,  f  After  the  mordanting 
and  fixing  operations  are  finished  too  long  a  time  should  not  elapse  before 
the  dyeing,  for  if  the  mordanted  cotton  is  exposed  for  any  length  of  time 
to  the  air  and  light  the  exposed  parts  will  turn  somewhat  brownish  and 
after  dyeing  will  appear  duller.  If  the  dyeing  cannot  be  carried  out  the 
3ame  day  as  the  mordanting  and  fixing,'  the  material  should  be  covered 
with  a  moistened  cloth. 

In  some  cases,  in  order  more  thoroughly  to  combine  any  excess  of  tartar 
emetic  in  the  fiber  after  fixing,  the  cotton  is  passed  back  into  the  tannin 
bath  (usually  a  rather  weak  one).  This  "  back-tanning  "  may  also  be  done 
after  dyeing;  it  also  appears  to  give  some  colors  a  greater  fastness  to 
washing.  As  antimony  compounds  are  of  a  poisonous  nature  they  should 
be  thoroughly  fixed  in  the  fiber,  as  otherwise  blood  poisoning  might  result 
from  fabrics  worn  next  the  skin.  In  certain  cases  (as  with  Victoria  Blue 
and  Methylene  Blue)  in  order  to  obtain  even  shades  it  is  necessary  to  wash 
the  cotton  after  fixing  for  fifteen  to  thirty  minutes  in  a  warm  soap  bath 
(containing  about  2  ozs.  soap  to  10  gallons  of  water),  and  afterwards  wash 
in  fresh  water.  This  treatment  usually  produces  clearer  and  more  even 
shades. 

In  the  dyeing  it  is  best  to  start  the  bath  cold,  using  twenty-five  to 
thirty  times  as  much  water  as  cotton  (1  lb.  of  cotton  would  therefore 
require  about  4  gallons  of  water),  and  adding  first  about  1  to  1|  per  cent 
of  acetic  acid;  this  serves  the  purpose  of  correcting  any  hardness  in  the 
water  and  thus  prevents  any  precipitation  of  coloring  matter,  and  also 
makes  the  bath  slightly  acid  which  avoids  too  rapid  an  exhaustion  of  dye- 
stuff  in  the  dyeing.     After  the  acid  has  been  placed  in  the  bath  a  portion 

which  reference  has  been  made  is  the  addition  of  common  salt  to  the  tartar  emetic  bath. 
This  addition,  it  has  been  shown,  increases  very  materially  the  amount  of  tannin  fixed 
upon  the  fiber.  Furthermore,  the  solution  of  tartar  emetic  may  be  made  much  more 
dilute,  and  the  time  of  treatment  may  be  considerably  reduced  to  obtain  the  maximum 
fixation  of  the  tannin.  The  amount  of  salt  recommended  to  be  used  in  this  connection 
is  about  6  ozs.  per  gallon,  and  the  addition  is  made  directly  to  the  bath  of  tartar  emetic. 

*  Sufficient  soda  ash  should  be  added  to  cause  a  slight  turbidity  in  the  bath.  Excess 
of  alkali  will  cause  loss  of  the  antimony  fixing  agent. 

t  In  the  case  of  dyeing  heavy  shades  where  a  strong  mordant  is  employed,  it  is  best 
to  give  the  goods  a  slight  soaping  after  fixing  with  tartar  emetic.  This  will  more  effect- 
ively remove  the  unfixed  mordant  and  give  colors  which  are  faster  and  more  uniform. 


260  BASIC  DAYS  ON  COTTON 

of  the  color  solution  is  added,  and  then  the  cotton  is  entered  and  worked 
for  about  ten  minutes;  the  material  is  then  lifted,  and  a  further  portion  of 
the  dyestuff  solution  added,  the  bath  being  heated  to  about  100°  F. 
Finally  the  rest  of  the  color  is  added  and  the  bath  is  raised  to  about  140 
to  160°  F.,  and  the  dyeing  completed.  In  place  of  acetic  acid,  an  addition 
of  about  3  per  cent  of  aluminium  sulphate  or  5  per  cent  of  alum  may  be 
made.*  In  the  case  of  certain  basic  colors  the  dyeing  is  finished  by  raising 
the  temperature  of  the  bath  to  the  boil,  as  with  Naphthindone.  f 

When  the  tannin  mordant  is  to  be  fixed  with  iron  instead  of  antimony, 
where  dark  colors  are  to  be  employed,  the  fixing  bath  is  made  up  with 
3  to  5  per  cent  of  copperas,  or  consists  of  nitrate  of  iron  at  3  to  4°  Tw. 
The  bath  is  employed  cold,  and  it  is  well  to  add  a  small  quantity  of  chalk 
(calcium  carbonate)  to  prevent  the  accumulation  of  acid  (from  the  acid 
combined  with  the  iron  salt  and  which  will  be  liberated  when  the  iron 
combines  with  the  tannin  to  form  tannate  of  iron) ;  about  2  to  4  per  cent 
of  chalk  will  be  all  that  is  necessary.  Dyeings  on  an  iron-tannin  mordant 
are  not  so  fast  t  as  those  on  an  antimony-tannin  base,  so  the  process  of 
fixing  with  iron  is  sometimes  modified  by  first  fixing  with  antimony  and 
subsequently  with  iron,  or  even  by  saddening  with  an  iron  liquor  after  the 
dyeing  is  finished. 

In  some  cases  increased  fastness  to  washing  for  basic  dyeings  may  be 
obtained  by  giving  the  dyed  goods  a  passage  through  the  tannin  bath 
(the  old  tannin  liquor  may  be  used),  wringing  out,  and  then  passing  through 
the  tartar  emetic  bath  again  and  washing  well.§ 

*  With  certain  dyes  alum  is  said  to  give  better  results  than  acetic  acid.  It  is  rec- 
ommended in  dyeing  Soluble  Blue,  Fast  Blues,  and  Nigrosines  to  use  5  to  10  per  cent  of 
alum  in  the  dyebath. 

t  Colors  dyed  with  Victoria  Blue  are  made  brighter  and  more  uniform  if  after  dyeing 
the  goods  are  soured  for  twenty  minutes  at  140°  F.,  with  1  to  3  per  cent  of  sulphuric  acid. 
After  souring,  the  goods  are  rinsed  and  soaped  at  180°  F.  for  twenty  minutes  with  10 
per  cent  of  soap. 

I  The  iron-tannin  lake  is  not  fast  to  acids,  as  these  decompose  the  lake  into  soluble 
compounds. 

§  It  will  generally  be  noted,  however,  that  this  treatment  has  a  tendency  to  dull  the 
colors  obtained;  though  shades  fast  to  boiling  soap  solution  may  be  obtained  in  this 
manner  with  the  following  dyes : 

Auramine  Brilliant  Green 

Acridine  Red  Pyronine  G 

Acridine  Scarlet  Capri  Green 

Acridine  Orange  Capri  Blue 

Cresyl  Blue  New  Metamine  Blue 

Fast  Blue  Victoria  Blue 

Indol  Blue  F.  Cresyl  Fast  Violet 

Malachite  Green  Methylene  Blue 
Safranine 


USE  OF   VARIOUS   MORDANTS  261 

An  aluminium-tannin  mordant  is  sometimes  used  for  the  production  of 
bright  pinks  with  the  Rhodamines.  The  yarn  is  mordanted  in  the  usual 
manner  with  tannic  acid;  squeezed,  and  passed  through  a  bath  containing 
20  gallons  of  aluminium  acetate  liquor  (9°  Tw.)  per  100  gallons  of  bath. 
Rinse  well  and  dye  with  Rhodamine. 

Certain  of  the  basic  colors,  such  as  Naphthindone  and  Irisamine,  may 
be  dyed  on  cotton  direct  without  a  mordant.*  The  dyebath  is  prepared 
with  3  to  5  lbs.  of  salt  per  10  gallons  of  liquor  according  to  the  depth  of 
shade;  the  dyeing  is  started  at  100°  F.,  and  the  bath  is  slowly  brought 
to  the  boil ;  after  dyeing  the  goods  are  simply  wrung  out  as  evenly  as  pos- 
sible and  dried.  This  method  is  not  often  practiced,  as  the  colors  obtained 
are  not  very  fast  to  washing  or  light,  f 

Cotton  may  also  be  dyed  with  basic  colors  by  using  other  mordants 
than  tannin.  A  fatty  acid  mordant  is  used  in  certain  cases,  especially  for 
light  and  brilliant  shades. 

Light  delicate  shades  may  be  obtained  by  dyeing  direct  on  bleached 
cottons  with  such  basic  dyes  as  Rhodamine,  Diamond  Green  or  Methylene 
Blue.  Use  a  dyebath  containing  1  to  2  per  cent  of  acetic  acid.  After 
dyeing,  squeeze  without  rinsing  and  dry.  The  colors  obtained  in  this 
manner,  of  course,  are  not  fast  to  washing.  {  The  following  dyes  may  also 
be  dyed  direct  on  cotton,  using  alum  in  the  bath:  Indone  Blue,  Indoine 
Blue,  Victoria  Blue,  Soluble  Blue,  Pure  Blue  and  Water  Blue.  The  dyeing 
is  carried  out  in  a  short  bath  at  140°  F.,  with  the  addition  of  1  to  4  per  cent 
of  alum;  then  slowly  bring  to  the  boil  and  work  for  twenty  minutes. 
Wring  and  dry  without  rinsing.  The  colors  obtained  in  this  manner  are 
very  brilliant  but  are  not  fast.  Methylene  Blue  and  Soluble  Blue  may  also 
be  dyed,  by  first  working  in  a  bath  containing  4  to  5  lbs.  of  soap  (per  100 
gallons)  for  one-half  hour  at  140°  F.;  squeeze  and  pass  through  a  cold 
bath  containing  2  lbs.  of  stannous  chloride  (per  100  gallons) ;  rinse  and  dye 


*  Indol  Blue  may  be  dyed  direct  by  adding  5  per  cent  of  alum  and  10  per  cent  of 
common  salt  to  the  bath  and  dyeing  at  180°  F.  for  one  hour.  Rinse  and  work  the 
material  in  a  fresh  bath  for  one-half  hour  at  90°  F.  with  1^  times  the  quantity  of  tannic 
acid  as  dyestuff.  By  using  the  tannin  bath  at  lower  temperature,  redder  shades  are 
obtained,  while  at  higher  temperatures,  the  shades  are  greener  in  tone. 

t  Single  Bath  Method  (Hochst) . — Use  a  cold  dyebath  containing  6  to  8  per  cent  of 
acetic  acid;  then  add  1  to  2  per  cent  of  tannic  acid,  and  finally  the  dyestuff  solution 
(up  to  1  per  cent).  Enter  the  cotton;  work  for  one-half  hour  cold,  then  one-quarter 
hour  at  110°  F.,  and  one-quarter  hour  at  140°  F.;  then  rinse,  wring  out,  and  dry. 
Faster  colors  are  obtained  by  dyeing  as  above  and  adding  to  the  first  rinsing  bath, 
^  to  H  per  cent  of  tartar  emetic.  Small  quantities  of  dyestuffs  may  be  added  to  this 
bath  for  purposes  of  shading. 

t  Very  brilliant  colors  may  be  obtained  with  Methyl  Cotton  Blue  by  dyeing  the 
bleached  cotton  in  a  bath  containing  1  lb.  of  alum,  5  lb.  of  tartar  emetic  and  the  required 
dyestuff;  work  for  one-half  hour  at  120°  F.,  then  squeeze  and  dry  without  rinsing. 


262 


BASIC  Dl'ES  ON  COTTON 


in  a  fresh  liath  containing  1  lb.  of  alum  (per  100  gallons)  for  one  hour  at 
140°  F.     Wring  and  dry. 

For  the  production  of  bright  pinks  on  cotton  certain  basic  dyes,  like 
Irisamine  and  Rhodaniine,  and  combinations  of  these  with  Auramine  and 
Safranine,  may  be  used  on  a  mordant  of  Turkey-red  oil.*  The  yarn  is 
mordanted  in  lots  of  1  pound  each  in  a  liquor  containing  1  part  Turkej'- 
red  oil  and  2  parts  of  water,  and  after  each  lot  is  mordanted  about  1  pint 
of  such  a  mixture  is  added  afresh.  Aft€r  mordantmg,  the  yam  is  ^\Tung 
out  well,  straightened  and  dried,  after  which  the  same  treatment  is  repeated. 
The  dyeing  is  conducted  in  a  cold  concentrated  bath  with  addition  of 
some  acetic  acid,  the  color  solution  being  added  in  several  portions.     In 


Fig.  156.— Franklin  Dyeing  Machine  for  Yarn,  etc.,  on  Spools  and  Cheeses. 


order  to  produce  level  shades  it  is  necessary  that  the  j^am  be  wrung  out 
as  evenly  as  possible  and  that  the  mordanting  be  repeated  several  times. 
When  hght  shades  and  bright  tints  are  to  be  dj'ed  on  cotton  it  will  be 
necessary  first  to  bleach  the  yarn  or  cloth  that  is  to  be  dyed  in  order  to 
pro\'ide  a  satisfactory  white  bottom  for  the  color.  For  this  character  of 
work  considerable  care  must  be  taken  in  the  bleaching  operations  to  have 
a  uniform  bleach,  and  to  avoid  any  degree  of  overbleaching  that  ma\- 
lead  to  the  formation  of  oxy cellulose,  as  such  conditions  will  almost  inev- 
itably result  in  uneven  dyeings  or  streaky  goods.     Bleached  cotton  also. 

*Basie  Dyes  on  a  Turkey-red  oil  mordant  or  on  an  alum  mordant  have  but  Umited 
appUcation  to  cotton,  as  the  colors  run  badly  and  are  not  fast  to  washing.  They  are 
sometimes  employed  where  great  briUiancy  is  the  chief  feature. 


TOPPING  WITH  BASIC  DYES  263 

as  a  rule,  shows  much  greater  affinity  for  the  color,  and  proper  precautions 
must  be  used  in  order  that  the  dyestuff  is  not  tak(ui  up  too  rapidly.  For 
the  production  of  certain  delicate  tints  on  bleached  cotton  several  of  the 
basic  dyes  may  be  used  without  a  mordant.  The  color  obtained  on 
bleached  cotton  is  much  faster  than  that  on  imbleached  cotton. 

Soap  may  also  be  used  as  a  source  of  the  fatty  acid  mordant,  in  which 
case  it  will  be  necessary  to  have  a  metallic  fixing  agent  in  order  to  form  an 
insoluble  compound  with  the  fatty  acid.  The  colors  obtained  with  fatty 
acid  mordants  are  usually  much  brighter  than  those  on  a  tannin  mordant, 
but  the  fastness  to  washing  is  very  poor  as  is  also  the  fastness  to  light.* 

Certain  dyestuffs  also  act  as  mordants  for  basic  colors.  Cotton  dyed 
with  sulphur  colors,  for  instance,  may  be  dyed  in  a  fresh  bath  with  basic 
dyes;  cotton  dyed  with  substantive  dyes  also  acts  in  the  same  manner. 
Only  a  comparatively  small  amount  of  basic  dye  (up  to  |  per  cent)  is  taken 
up  in  this  process,  but  it  is  sufficient  to  considerably  influence  the  shade. 
The  process  is  chiefly  used  for  the  purpose  of  brightening  the  colors  obtained 
with  sulphur  or  substantive  dyes,  and  the  operation  is  called  "  topping." 
The  colors  obtained  have  a  fairly  good  fastness,  as  a  rule,  especially  if 
after-treated  with  tannin  and  tartar  emetic.  Cotton  dyed  with  Alizarine 
dyes,  Logwood  and  the  natural  dye-woods,  and  Aniline  Black  may  also  be 
topped  with  basic  dyes. 

Though  in  dyeing  operations,  tannin  and  fatty  acid  mordants  are  about 
the  only  ones  employed  in  practice  for  basic  dyes,  there  are  a  number  of 
other  mordants  which  have  been  proposed  for  use  in  printing.  For  instance, 
the  sulphides  of  zinc  and  tin  have  been  used,  as  well  as  the  zinc  salts  of 
hydroferro-  and  hydroferricyanic  acids,  obtained  by  precipitating  zinc 
salts  with  yellow  prussiate  and  red  prussiate  of  potash  (see  Balanche, 
Jour.  Soc.  Chem.  Ind.,  1882,  p.  182  and  Reber,  ihid.,  1885,  p.  343). 

Besides  their  general  use  in  the  dyeing  of  textiles,  the  basic  dyes  are  ^■-'^ 
also  largely  used  for  the  preparation  of  writing  and  hectographic  inks, 
lakes  for  lithographic  inks,  for  coloring  typewriter  ribbons,  copy-paper, 
pencils,  etc. 

2.  Substances    Employed    for    Mordanting    Cotton. — Tannins.     By   , 
the  general  term  "  tannins  "  is  meant  a  number  of  related  organic  acids  ^ 
which  occur  as  the  astringent  principles  in  vegetable  life.     They  are  gen-  (-■ 
©rally  analogous  in  their  chemical  properties  and  are  characterized  by  their 

*  The  method  of  mordanting  cotton  with  soap  is  as  follows:  Use  a  bath  containing 
2  gallons  of  water  and  2  lbs.  of  neutral  soap  at  about  180°  F.  Steep  the  cotton  in  lots  of 
1  lb.  each  in  this  bath  for  several  minutes;  wring  out  and  dry  at  a  moderate  heat. 
For  heavier  mordanting,  the  operations  must  be  repeated  several  times.  To  fix  the 
fatty  acid,  work  the  cotton  in  a  bath  consisting  of  a  dilute  solution  of  aluminium  acetate 
at  150°  F.  (1  gallon  of  aluminium  acetate  liquor,  8°  Tw.,  to  200  gallons  of  water). 
Wash,  squeeze,  and  pass  through  a  weak  soap  bath  (1  lb.  of  soap  to  100  gallons  water). 
Finally  wash  well  and  dye, 


264  BASIC  DYES  ON  COTTON 

property  of  tanning  animal  skins  (that  is,  converting  the  animal  tissue 
into  leather),  forming  insoluble  compounds  with  albumin,  precipitatirig 
basic  ch'cs  from  solution,  and  yielding  bluish  or  greenish  bIacKcoTorsl\'ith. 
solutions  of  iron  salts.  The  majority  of  the  natural  tannins  also  contain  -^ 
yellowish  or  brownish  coloring  matters;  pure  tannic  acid,  however,  has X 
no  special  color.  Some  of  the  tannins,  such  as  decoctions  of  gallnuts 
and  extracts  of  sumac,  may  be  almost  entirely  decolorized  by  proper 
methods  of  treatment.  AVhere  delicate  and  bright  colors  are  to  be  obtained 
on  cotton  with  basic  dyes  it  will  be  necessary  to  employ  either  pure  tannic 
acid  or  a  decolorized  sumac  extract. 

Though  cotton  is  in  general  very  inert  towards  solutions  of  organic 
acids,  it  appears  to  possess  considerable  affinity  for  tannic  acid,  and  will 
absorb  it  readily  from  its  solutions.  Tannins  should  be  stored  in  a  dry 
place,  as  continued  exposure  to  damp  air  will  cause  the  tannic  acid  to 
decompose,  giving  brownish  colored  resinous  substances.  The  following 
are  the  most  important  tannins  employed  in  the  mordanting  of  cotton:         / 

(1)  Tannic  acid,  or  gallo-tannic  acid,  is  prepared  especially  from  gall->^ 
nuts,  which  are  very  rich  in  this  acid.  Tannic  acid  comes  on  the  market 
in  the  form  of  a  light  brown  powder  or  yellowish  to  brownish  scales  which 
usually  darken  somewhat  on  exposure  to  light.  It  is  soluble  in  6  parts  of 
cold  water,  and  in  even  a  less  quantity  of  hot  water ;  it  is  also  f reel}^  solu- 
ble in  alcohol,  dilute  acetic  acid,  and  glycerin.  Solutions  of  tannic  acid, 
and  also  of  any  of  the  tannins,  will  gradually  undergo  feraientation  and 
become  destroj-ed.  In  order  to  prevent  this  decomposition  in  standing 
baths  used  for  mordanting,  it  is  advisal^le  to  boil  up  the  baths  repeatedly 

or  to  add  a  small  amount  of  carbolic  acid  to  them.     When  used  as  a      \ 

standing  Imth  aliout  70  per  cent  of  the  amount  of  tannin  originally  added 

to  the  first  bath  should  be  used  for  replenishing.  •  ^ 

(2)  Sumac  is  next  in  importance  to  tannic  acid  for  purposes  of  ^ 
dyeing  cotton.  The  sumac  from  the  Rhus  coriaria  is  considered  the 
best  and  it  contains  gallo-tannic  acid.  Sicilian  smnac  is  the  best 
and  least  colored  variety;  after  this  comes  the  American  (Virginian) 
sumac,  which  can  now  be  obtained  in  very  good  qualities.  Commercial 
sumac  usuallj'  consists  of  the  whole  or  the  crushed  or  pulverized  leaves, 
though  the  stalks  and  small  stems  are  frequently  admixed.  Good  quali- 
ties have  an  olive-green  color  and  a  pleasant  smell;  they  contain  from  15 
to  20  per  cent,  and  sometimes  as  high  as  25  per  cent  of  tannin.  Sumacs 
which  are  dull  in  color  and  of  a  musty  smell  have  deteriorated  by  exposure 
to  moist  air  and  prolonged  storing.  Sumac  contains  a  small  amount  of  dull 
reddish  brown  coloring  matter,  which  prohibits  its  use  in  most  cases  for 
light  and  brilliant  shades,  so  that  it  is  chiefly  employed  for  dark  shades. 
Sumac  extract  is  a  thick  dark  brown  liquid  or  paste,  usually  of  about  52° 
Tw.  density.     It  also  occurs  in  the  sohd  state.     Decolorized  sumac  extracts 


TANNINS   USED   IN   MORDANTING 


265 


are  also  to  be  had,  and  may  be  used  in  place  of  pure  tannic  acid  for  light 
colors.  Liquid  sumac  extracts  are  very  liable  to  fermentation,  especially 
if  kept  in  a  warm  moist  room. 

(3)  Galls,  or  gallnuts,  are  ball-shaped  excrescences  which  grow  on 
various  plants,  especially  oak  trees,  and  result  from  the  sting  of  an  insect 
in  depositing  its  eggs.  Of  the  oak-galls,  the  green  or  black  Aleppo  galls" 
and  the  Turkish  or  Levant  galls  are  the  best  and  contain  about  55  to  60 
per  cent  of  gallo-tannic  acid.  Chinese  and  Japanese  galls  contain  up  to 
80  per  cent  of  gallo-tannic  acid,  and  these  are  principally  used  for  the  pro- 
duction of  pure  tannic  acid. 

(4)  Myrobolans  consist  of  the  fruit  of  several  Chinese  and  Indian  plants, 
and  they  occur  in  trade  in  the  dry  state ;  they  contain  25  to  45  per  cent  of 


Fig.  157. — Perforated  Spindles  for  Cops  and  Tubes  for  Dyeing. 


tannin  and  a  yellowish  brown  coloring  matter.  They  are  not  much  used 
in  this  country,  though  sometimes  employed  for  dyeing  cotton  black. 

((5)  Divi-divi  is  the  fruit  of  certain  plants  in  Central  and  South  America; 
they  contain  20  to  35  per  cent  of  tannin,  and  are  used  in  the  same  way  as 
myrobolans.  There  are  many  other  tannin  substances  which  are  more  or 
less  locally  employed  where  they  are  to  be  obtained  in  abundance,  but  the 
above  mentioned  varieties  are  the  principal  ones  to  be  met  with  in  trade. 
In  the  mordanting  of  cotton  for  dyeing,  1  lb.  of  pure  tannic  acid  is  equiva- 
lent to  about  1|  to  2  lbs.  of  gallnuts,  or  4  lbs.  of  sumac  extract  of  25  per 
cent  strength,  or  to  5  to  6  lbs.  of  sumac  leaves. 

3.  Tartar  Emetic  and  Antimony  Salts. — Tartar  emetic  is  the  double  tai*^ 
trate  of  antimony  and  potassium;  it  is  a  crystalline  salt  and  is  not  very 
s^iible  in  cold  water,  but  it  is  rather  easily  soluble  in  hot  water.*     One 

*  The  solubility  of  tartar  emetic  may  be  much  increased  by  the  addition  of  common 
salt.     Prudhomme,  who   first   observed  this  fact  (Bull,  de  Mulhouse,   1890,  p.  549) 


^ 


266  BASIC  DYES  OX  COTTON 

part  of  the  salt  requires  about  13  parts  of^ water  for  solution  at  70°  F.  and 
only  about  3  parts  of  water  at  180°  F.  The  active  principle  in  tartar  emetic 
which  enters  into  the  fixation  of  the  tajiiiin  in  the  mordanting  of  cotton  is 
the  antimony  trioxide,  Sb^Os,  of  which  the ^pure  salt  contains  43.4  per  cent. 
The  commercial  product  consists  of  fine  crystals  of  irregular  lumps  con- 
taining about  43  per  cent  of  antimonj'-  trioxide.  It  is  frequently  adul- 
terated with  cheaper  substances.  Though  tartar  emetic  and  the  rest  of 
the  salts  of  antimony  are  poisonous,  no  ill  effects  need  be  feared  from  its 
use  in  dyeing,  if  the  goods  are  well  washed  after  mordanting.  As  tartar 
emetic  is  rather  an  expensive  chemical,  it  is  often  replaced  by  cheaper 
salts  of  antimony,  which  have  the  same  effect  in  the  fixation  of  the  tannic 
acid.     The  chief  substitutes  are  as  follows: 

(1)  Antimony  salt,  which  is  the  doul)lc  salt  of  antimony  fluoride  and 
ammonium  sulphate;  it  occurs  as  white  crystals,  oT'Whiclrt40^arts  are 
soluble  in  100  parts  of  water.  The  solution  is  strongly  acid  and  corrodes 
glass  and  metals,  OAving  to  the  hydrofluoric  acid  liberated.  Antimony  salt 
contains  47  per  cent  of  antimony  trioxide;  hence  9  parts  are  equivalent 
to  10  parts  of- tartar  emetic. 

(2)  Patent  salt,  or  double  antimony  fluoride,  is  antimony -sodium 
fluoride.  It  is  also  crystalline  and  readily  soluble,  and  likewise  corrodes 
glass  and  metals.  It  contains  66  per  cent  of  antimony  trioxide;  hence 
65.8  parts  of  this  salt  are  equivalent  to  100  parts  of  tartar  emetic.  Of 
these  two  double  fluorides  of  antimony,  5  to  20  parts  are  dissolved  in  1000 
parts  of  water,  and  their  strong  acidit}^  is  neutralized  by  the  addition  of  6.,- 
to  8  per  cent  in  weight  of  soda  ash,  or  just  enough  to  render  the  bath 
slightly  turbid. 

(3)  Antimony  oxalate  is  the  double  oxalate  of  potassium  and  antimony, 
and  was  introduced  as  the  first  cheap  substitute  of  tartar  emetic;  it  has 
given  much  satisfaction,  but  has  been  nearlj^  superseded  by  the  double 
fluorides.  It  occurs  as  crj^stals  which  are  readilj'  soluble  in  water,  but 
which  dissociate  rapidly  into  an  insoluble  Ijasic  oxalate  of  antimonj^  and  a 
soluble  binoxalate.  It  contains  only  25.1  per  cent  of  antimony  trioxide, 
as  against  43.4  per  cent  in  tartar  emetic;  though  it  is  claimed  to  replace 
equal  weights  of  the  latter,  as  it  combines  more  rapidly  with  tannic  acid. 

(4)  Antimonine  is  the  double  lactate  of  antimony  and  calcium.  It 
occurs  as  crystals  containing  15  per  cent  of  antimony  trioxide,*  it  is  hygro- 

attributed  it  to  the  formation  of  a  molecular  compound  between  the  salt  and  the  tartar 
emetic.  This  view,  however,  has  later  been  disproved,  and  the  reaction  is  attributed  to  a 
reversible  double  decomposition  between  the  two  salts,  as  follows: 

K(SbO)C4H406+NaCl  <=±  Na(SbO)C4H406+KCl, 
and  it  is  the  formation  of  the  sodium  salt  which  accounts  for  the  increased  solubility. 

*  It  is  said,  however,  to  have  the  same  effect,  weight  for  weight,  as  tartar  emetic, 
as  aU  of  the  antimony  oxide  it  contains  enters  into  the  reaction.     This  claim  seems  hardly 


^ 


ANTIMONY   FIXING   SALTS  267 

scopic  and  very  readily  soluble.  It  should  be  employed  in  a  weakly  acid 
solution,  that  is,  with  the  addition  of  about  1|  pints  of  acetic  acid  per  100 
gallons  of  liquor.     This  product  is  quite  extensively  employed. 

The  fixing  bath  of  tartar  emetic,  like  that  of  the  tannin,  may  be 
employed  continuously,  being  freshened  up  accordingly.  As  the  bath 
becomes  acid  on  using,  due  to  the  removal  of  the  antimony  trioxide,  a 
little  soda  ash  should  be  added  from  time  to  time  to  neutralize  the  acid  as 
it  accumulates;  this  is  best  done  by  adding  a  dilute  solution  of  soda  ash 
until  a  slight  turbidity  is  apparent.*  If  the  liberated  tartaric  acid  is 
allowed  to  accumulate  without  being  neutralized,  it  will  act  so  as  to  redis- 
solve  the  precipitated  antimony  tannate,  and  thus  lessen  the  value  of  the 
fixing  bath. 

4.  Experimental.  Exp.  91.  General  Method  of  Dyeing. — As  cotton  does  not  possess 
acidic  properties,  it  does  not  combine  directly  with  basic  dyes,  but  requires  an  acid  sub- 
stance (mordant)  to  be  added  to  tlie  fiber  in  order  for  the  dyeing  to  take  place.  Cotton 
readily  absorbs  tannic  acid  from  solution,  and  as  this  acid  forms  good  color-lakes  with 
the  basic  dyes,  it  is  a  very  suitable  mordant  for  cotton  in  this  connection.  To  illustrate 
this  reaction,  proceed  as  follows:  Steep  a  skein  of  cotton  yarn  in  a  bath  containing  300  cc. 
of  water  and  2  per  cent  of  tannic  acid;  enter  at  120°  F.,  raise  to  190°  F.,  then  allow  the 
skein  to  remain  immersed  in  the  bath  without  further  heating,  as  it  is  found  that  the 
maximum  amount  of  tannicacid  is  absorbed  from  a  cooling  bath.  Now  squeeze  the  skein, 
and  together  with  an  unmordanted  skein  of  cotton  yarn  pass  into  a  dyebath  containing 
300  cc.  of  water  and  1  per  cent  of  Methylene  Blue;  enter  at  100°  F.,  gradually  raise  to 
190°  F.,  and  dye  at  that  temperature  for  one-half  hour;  wash  well  and  dry.  It  will  be 
found  that  the  mordanted  skein  has  become  dyed,  whereas  the  other  skein  has  only 
become  slightly  tinted  As  tannic  acid  is  liable  to  suiTer  decomposition  at  the  boil, 
giving  rise  to  brown  coloring  matters  and  resinous  products,  it  is  not  recommended  to 
boil  the  mordanting  bath,  as  the  shade  eventually  obtained  will  probably  be  dulled. 
The  tannin,  by  this  method  of  treatment,  is  not  held  in  an  insoluble  state  in  the  cotton, 
so  that  when  the  goods  are  placed  in  the  dyebath  some  of  the  tannic  acid  passes  again 
into  solution  in  the  dye  liquor,  causing  some  of  the  dyestuff  to  be  precipitated  and 
also  causing  a  loss  of  color  to  the  fiber.  Hence  it  is  customary  to  fix  the  tannic  acid  in 
an  insoluble  condition  on  the  fiber  before  passing  into  the  dyebath,  as  will  be  described 
in  a  succeeding  experiment.  Tannin  is  a  vegetable  astringent  principle  and  occurs  in 
many  plants  or  vegetable  extracts,  such  as  sumac  (containing  about  20  per  cent  of  tannic 
acid),  cutch  (containing  about  40  per  cent  of  tannic  acid),  etc.  These  vegetable  extracts 
may  be  used  in  place  of  tannic  acid  itself,  provided  sufficient  amount  of  them  be  taken 
to  give  the  proper  amount  of  actual  tannic  acid.  Many  of  these  vegetable  extracts, 
however,  also  contain  more  or  less  brown  coloring  matters  associated  with  the  tannin, 
and  these  are  absorbed  by  the  cotton,  causing  the  latter  to  become  considerably  colored 
in  the  mordanting. 

Exp.  92.  Fixing  Tannin  on  Cotton  with  Tartar  Errietic. — In  order  to  fix  the  tannin 
mordant  absorbed  by  the  cotton  from  the  mordanting  bath  so  that  it  will  not  dissolve 

probable,  as  it  would  mean  that  the  tartar  emetic  is  only  one-third  exhausted  from 
the  fixing  bath. 

*The  addition  of  common  salt  to  the  fixing  bath  is  .said  to  be  more  beneficial  than 
that  of  soda  ash,  as  the  presence  of  salt  causes  the  quantitative  fixation  of  the  tannin 
by  the  tartar  emetic. 


268 


BASIC  DYES  ON  COTTON 


into  the  dyebath,  it  is  best  to  combine  it  with  some  metallic  base  anri  so  form  an  insoluble 
tannate.  Most  of  the  tannates  of  the  metals  are  dark  in  color,  hence  unsuitable  for 
dyeing,  except  for  the  production  of  a  limited  range  of  shades.  The  tannate  of  anti- 
mon3%  however,  possesses  but  very  little  color,  and  scarcely  affects  the  resulting  color 
of  the  dye.  Tartar  emetic  is  potassium  antimony  tartrate,  and  it  is  the  antimony  oxide 
present  in  the  salt  which  serves  the  purpose  of  fixing  the  tannin ;  that  is,  the  tannin  reacts 
with  the  tartar  emetic  to  form  antimony  tannate.  Proceed  as  follows:  Mordant  a 
skein  of  cotton  yarn  in  a  bath  containing  300  cc,  of  water  and  2  per  cent  of  tannin  as 


Fig.  158. — Dyeing  Machine  for  Cops,  etc.     (riaubold). 


before  described;  squeeze  and  pass  into  a  fresh  bath  containing  300  cc.  of  water  and  1 
per  cent  of  tartar  emetic;  work  cold  for  fifteen  minutes.  Then  wash  well  in  fresh 
water  to  remove  any  excess  of  the  antimony  compound  and  any  unfixed  tannin,  and  pass 
to  a  dyebath  containing  300  cc.  of  water,  1  per  cent  of  Methyl  Violet,  and  2  per  cent  of 
acetic  acid;  enter  at  100°  F.,  gradually  raise  to  190°  F.,  and  dye  at  that  temperature 
for  one-half  hour.  The  amount  of  tannin  used  in  mordanting  should  be  about  twice 
that  of  the  dyestuff,  and  the  amount  of  tartar  emetic  should  be  about  one-half  that  of 
the  tannin.  The  acetic  acid  is  employed  for  the  purpose  of  retarding  the  dyeing,  so  as 
to  promote  even  and  well  penetrated  colors. 


EXPERIMENTAL  STUDIES  269 

Exp.  93,  Fixing  Tannin  with  Copperas. — Copperas  is  iron  sulphate,  and  as  it  occurs 
in  the  form  of  green  crj^stals,  it  is  known  as  "  green  vitriol."  Salts  of  iron  combine  with 
tannic  acid  to  give  black  tannate  of  iron,  hence  tannin  fixed  on  cotton  with  copperas  or 
other  iron  salts  gives  the  fibers  a  gray  to  black  color,  which,  of  course,  affects  the  shade 
eventually  dyed  on  the  mordant.  Mordant  a  skein  of  cotton  yarn  in  the  manner 
described  above  with  2  per  cent  of  tannin,  squeeze,  and  steep  for  fifteen  minutes  in  a 
cold  bath  containing  300  cc.  of  water,  5  per  cent  of  copperas  and  5  per  cent  of  whiting. 
The  latter  is  calcium  carbonate  or  chalk,  and  is  added  in  order  to  keep  the  bath  neutral, 
for  when  the  tannic  acid  combines  with  the  iron  of  the  copperas  there  is  liberated  some 
sulphuric  acid,  and  as  tannate  of  iron  is  soluble  in  sulphuric  acid,  it  will  be  redis- 
solved.  The  chalk  in  the  bath  combines  with  the  sulphuric  acid  as  fast  as  formed, 
and  thus  keeps  the  bath  neutral,  so  that  the  iron  is  able  to  combine  fully  with  the 
tannic  acid.  Wash  the  mordanted  skein,  which  wiU  now  have  a  gray  or  slate  color,  and 
preserve  a  sample  for  comparison,  then  dye  the  rest  of  the  skein  in  a  bath  containing 
300  cc.  of  water,  1  per  cent  of  Methylene  Blue  and  2  per  cent  of  acetic  acid  in  the 
usual  manner.  Wash  and  dry.  In  the  same  bath  with  this  skein  also  dye  a  skein 
of  cotton  yarn  which  has  been  mordanted  in  the  usual  manner  with  tannin  and  fi.xed 
with  tartar  emetic.  Notice  the  difference  in  the  colors  obtained,  due  to  the  iron  mor- 
dant; also  compare  the  mordant  color  with  the  dyed  color,  and  note  the  influence  of 
the  bottom  color  of  the  mordant  on  the  resulting  color-lake. 

Exp.  94.  Use  of  Other  Agents  in  Dyeing  Basic  Dyes. — Mordant  a  test  skein  of 
cotton  yarn  in  a  bath  containing  300  cc.  of  water  and  20  per  cent  of  sumac  extract. 
Enter  at  190°  F.,  work  the  cotton  in  the  bath  for  fifteen  minutes,  then  steep  under  the 
liquor  for  one  hour  without  further  heating.  Squeeze  the  skein  and  pass  into  a  fresh 
bath  containing  300  cc.  of  water  and  2  per  cent  of  antimony  salt  (a  double  salt  of  anti- 
mony fluoride  with  ammonium  sulphate);  work  cold  for  fifteen  minutes,  then  wash 
well  and  dye  in  a  fresh  bath  containing  300  cc.  of  water,  5  per  cent  of  alum,  and  2  per 
cent  of  Thioflavine  T.     Conduct  the  dyeing  operation  as  usual.     Wash  well  and  dry. 

Exp.  95.  Dyeing  Basic  Colors  in  One  Bath. — Prepare  a  cold  bath  containing  300  cc. 
of  water,  6  per  cent  of  acetic  acid,  2  per  cent  of  tannic  acid,  and  1  per  cent  of  JNIalachite 
Green.  Dye  a  skein  of  cotton  yarn  in  this  bath  cold  for  fifteen  minutes,  then  raise  the 
temperature  to  105°  F.  for  fifteen  minutes,  and  finally  to  140°  F.  for  fifteen  minutes; 
then  rinse  the  skein,  squeeze,  and  dry.  The  fastness  to  washing  of  the  colors  dyed  in 
this  manner  may  be  increased  by  first  rinsing  after  dyeing  in  water  containing  5  to  2 
per  cent  of  tartar  emetic.  This  method  is  only  applicable  to  amounts  of  dyestuff  up 
to  about  1  per  cent.  The  color-lake  is  held  in  solution  by  the  presence  of  the  acetic 
acid,  and  only  separates  out  gradually  in  the  fiber  on  heating  the  bath. 

Exp.  96.  Use  of  the  Janus  Dyes. — These  dyestuffs  are  basic  colors  which  also  pos- 
sess substantive  or  direct  dyeing  properties,  though  to  form  a  fast  color-lake  it  is  neces- 
sary to  fix  the  dye  with  tannin.  Prepare  a  dyebath  containing  300  cc.  of  water,  2  per 
cent  of  acetic  acid,  5  per  cent  of  zinc  sulphate,  and  2  per  cent  of  Janus  Red.  Add  only 
a  portion  of  the  dyestuff  solution  at  first;  enter  the  cotton  skein  at  about  200°  F.,  work 
for  ten  minutes,  then  add  the  remainder  of  the  dyestuff;  work  for  ten  minutes  longer,  and 
then  add  20  per  cent  of  common  salt,  and  work  for  one-half  hour  at  the  boil.  Rinse  the 
dyed  cotton,  and  pass  into  a  fixing  bath  containing  300  cc.  of  water,  4  per  cent  of  tannic 
acid;  work  cold  for  fifteen  minutes;  then  lift  the  skein  and  add  to  the  bath  2  per  cent 
of  tartar  emetic  and  1  per  cent  of  sulphuric  acid,  and  work  cold  for  fifteen  minutes  longer, 
then  raise  the  temperatm-e  to  140°  F.  for  fifteen  minutes.     Finally  wash  well  and  dry. 


CHAPTER   XII 


PRINCIPAL  BASIC  DYES 


1.  List  of  the  Principal  Basic  Dyes. — The  basic  dyes  do  not  include 
such  a  large  list  as  the  acid  dyes,  though  the  apparent  number  is  consider- 
ably increased  by  the  fact  that  the  same  dyestuff  is  frequently  given  a 
variety  of  different  names,  and  furthermore,  a  number  of  mixtures  are 
marketed  under  specific  names.  Some  of  these  dyes  are  more  adapted 
to  the  dyeing  of  silk  than  of  cotton,  and  vice  versa;  this  can  only  be  deter- 
mined by  reference  to  the  specific  properties  of  the  individual  dyestuffs. 


Aoridino  Rod 

Acridine  Scarlet 

Aniline  Maroon 

Aniline  Scarlet 

Anisoline 

Bordeaux 

Brilliant  Rhoduline  Red 

Brilliant  Rose 

Brilliant  Safranine 

Camelia 

Cardinal 

Cardinal  Red 

Carthamine 

Cerise 

Clemantine 

Cotton  Red 

Diamond  Fuchsine 


Acridine  Orange 
Azo  Phosphinc 
Brilliant  Phosphine 
Canelle 
Chrysoidine 
Coriphospliine 


Acridine  Golden  Yellow 

Acridine  Yellow 

Aniline  Yellow 

Auracinc 

Auraminc 

Aurophosiihinc 


(a)  Red 
Diamond  Magenta 
Fast  Pink 
Fast  Red 
Fuchsine 
Geranium 
Grenadine 
Induline  Scarlet 
Irisamine 
Isorubine 
Janus  Bordeaux 
Janus  Red 
Magenta 
Magenta  Scarlet 
Maroon 
Neutral  Rod 
Neutral  Scarlet 
New  Magenta 

(b)  Orange 
Cotton  Orange 
Diamond  Phosphine 
Flavinduline 
Flavophosphine 
Homophosphine 
New  Acridine  Orange 

(c)  Yellow 
Benzoflavine 
Corioflavine 
Euchrysine 
Flavazol  Yellow 
Janus  Yellow 
Leather  Yellow 

270 


Parafuchsine 
Patent  Rhodamine 
Pyronine 

Rhodamine  B,  G,  6G 
Rhodine 
Rhoduline  Pink 
Rhoduline  Red 
Rhoduline  Scarlet 
Rosazeine 
Rosolc  Rod 
Rosole  Scarlet 
Rubine 
Russian  Red 
Safranine 
Safranine  Scarlet 
Tannate  Fast  Scarlet 
Taunate  Rubine 


New  Phosjihine 
Paraphosphine 
Patent  Phosphine 
Phosphine 
Rhoduline  Orange 
Tannin  Orange 


Methylene  Yellow 
Philadelphia  Yellow 
Rheonine 
Rhoduline  Yellow 
Thioflavine  T 
Xanthine 


LIST  OF   BASIC   DYES 


271 


Azine  Green 
Bengal  Green 
Benzol  Green 
Brilliant  Green 
Capri  Green 
China  Green 
Diamond  Green 
Diazine  Green 
Emerald  Green 


(d)  Green 

Ethj'l  Green 
Fast  Greens 
Imperial  Green 
Janus  Green 
Light  Green 
Malachite  Green 
Methyl  Green 
Methylene  Green 


New  Fast  Green 
New  Green 
New  Solid  Green 
New  Victoria  Green 
Tannate  Dark  Green 
Tannate  Fast  Green 
Victoria  Green 
Zinc  Green 


Acetine  Blue 
Acetinduline 
Alkali  Blues 
Alkaline  Blue 
Azindone  Blue 
Azure  Blue 
Basle  Blue 
Bavarian  Blue 
Bengal  Blue 
Blackley  Blue 
Bleu  de  Lyon 
Bombay  Blue 
Brilliant  Blue 
Brilliant  Cresyl  Blue 
Brilliant  Diazine  Blue 
Brilliant  Glacier  Blue 
Brilliant  Metaminc  Blue 
Brilliant  Victoria  Blue 
Capri  Blue 
China  Blue 
Cotton  Blue 
Cotton  Light  Blue 
Cresyl  Blue 
Crystal  Fast  Blue 
Dark  Blue 
Diazine  Blue 
Diphene  Blue 
Diphenylamine  Blue 
Ethyl  Blue 
Ethj'lene  Blue 
Excelsior  Cotton  Blue 
Fast  Blue 

Fast  Blue  for  Cotton 
Fast  Cotton  Blue 
Fast  Marine  Blue 
Fast  Navy  Blue 
Fast  New  Blue 


(e)  Blue 

Gentianine 
Glacier  Blue 
Helvetia  Blue 
Indamine  Blue 
Indanil  Blue 
Indazine 
Indigen 
Indigo  Blue 
Indine  Blue 
Indoine 
Indoine  Blue 
Indol  Blue 
Indone  Blue 
Indopheniue  Blue 
Janus  Blue 
Janus  Dark  Blue 
Jute  Blue 
Light  Blue 
Madras  Blue 
Malta  Blue 
Marine  Blue 
Meldola's  Blue 
Metaphenylene  Blue 
Methyl  Blue 
Methyl  Cotton  Blue 
Methyl  Indone 
Methyl  Light  Blue 
Methyl  Water  Blue 
Methylene  Blue 
Methylene  Dark  Blue 
Methylene  Indigo 
Muscarine 
Naphthindone 
Naphthol  Blue 
Neutral  Blue 
Neutral  Peacock  Blue 
New  Blue 


New  Cotton  Blues 

New  Diamond  Indigo  Blue 

New  Ethyl  Blue 

New  Fast  Blue 

New  Indigo  Blue 

New  Metamine  Blue 

New  Methylene  Blue 

New  Solid  Blue 

Now  Victoria  Blue 

Night  Blue 

Nile  Blue 

Opal  Cotton  Blue 

Paper  Blue 

Paraphenylcne  Blue 

Peacock  Blue 

Phenine  Blue 

Phonine  Navy  Blue 

Phenvlene  Blue 

Printing  Blue 

Pure  Blue 

Rhoduline  Blue 

Rhoduline  Sky  Blue 

Setocyanine 

Setoglaucine 

Setopaline 

Solid  Blue 

Soluble  Blues 

Swiss  Blue 

Thiazine  Blue 

Thionine  Blue 

Toluidine  Blue 

Toluylene  Blue 

Turkey  Blue 

Turquoise  Blue 

Victoria  Blues 

Victoria  Night  Blue 

Water  Blue 


272 


PRINCIPAL  BASIC  DYES 


Brilliant  Rhoduline  Purple 

Brilliant  Violet 

Clematine 

Cresyl  Fast  Violet 

Crystal  V^iolet 

Dahlia 

Ethyl  Purple 

Ethyl  Violet 

Fast  Neutral  Violet 

Girofld 

Heliotrope 


Acridine  Brown 
Bismarck  Brown 
Brown  (wtra  soluble 
Cutch  Brown 
Excelsior  Brown 


Coal  Black 
Diazine  Black 
Direct  Gray 
Fast  Black 
Fast  Gray 
Gray  NO 
Janus  Black 
Janus  Gray 
Jet  Black 


(f)  Violet 
Hofmann's  Violet 
Irisamine 
Iris  Violet 
Methyl  Violets 
Methylene  Heliotrope 
Methylene  Violet 
Neutral  Violet 
Paraphenylene  Violet 
Paris  Violet 
Primula 

(g)  Brown 
Janus  Brown 
Leather  Brown 
Manchester  Brown 
Nut  Brown 

(h)  Black 

Jute  Black 
Jute  Coal  Black 
Leather  Black 
Logwood  Substitute 
Malta  Gray 
Methylene  Gray 
Neutral  Black 
New  Fast  Gray 


Red  Violet 
Regina  Violet 
Rhoduline  Heliotrope 
Rhoduline  Violet 
Rosolane 
Rubine  Violet 
Soda  Violet 
Tannate  Violet 
Tannin  Heliotrope 
Violets 


Phenylene  Brown 
Rheonine 
Tannin  Brown 
Vesuvine 


New  Gray 

New  Methylene  Gray 

Nigrosine 

Paper  Black 

Silk  Gray 

Straw  Black 

Tannate  Fast  Black 

Tannate  Gray 


Fig.  159.— Open  Horizontal  Dyeing  or  Bleaching  Machine  for  Warper's  Beams,  Cops, 

and  Cross-wound  Bobbins.     (Pornitz.) 


PRACTICAL  DYEING  OF  BASIC  COLORS  273 

2.  Notes  on  the  Practical  Dyeing  of  Basic  Colors. — The.basic-dyes  are-  ^ 
very  seldom  employed  for  the  dyeing  of  cotton  or  loose  stock,  as  the  mor-^jL. 
danting  makes  the  cotton  somewhat  harsh  and  bad  to  work  in  the  subse-  i 
quent  processes  of  spinning.     Yarn,  however,  both  as  skein  and  warp,  is 
extensively  dyed  with  these  colors,  and  the  same  is  also  true  of  piece-goods^-- 
Skein  yarn  is  mordanted,  fixed,  and  dyed  in  the  usual  forms  of  apparatus - 
either  hand-dyed  in  the  tubs  or  dyed  on  suitable  skein  machines.     Warps 
may  best  be  handled  by  first  impregnating  with  the  tannin  solution  in  an  ^ 
ordinary  warp-dyeing  machine,  then  laying  down  in  the  tannin  and  steep- 
ing overnight.     The  fixing  and  dyeing  are  done  I)}'-  running  in  the  ordinary 
warp  machine.     In  the  case  of  light  shades  on  Avarps,  the  mordanting  a,mL- 
fixing  may  be  carried  out  in  a  continuous  six-box  warp  machine;    the 
first  two  boxes  containing  the  tannin  solution,  the  next  two  the  fixing  bath 
of  tartar  emetic  (with  the  addition  of  a  small  amount  of  chalk),  while  the 
last  two  boxes  are  used  for  rinsing.     Warps  which  are  hard-twisted  should 
always  be  soaped  after  mordanting  to  insure  even  colors.     In  the  applica- 
tion of  the  dyestuff  to  Avarps,  the  bath  should  contain  acetic  acid  or  alum, 
and  the  first  end  should  be  run  cold,  and  best  without  any  addition  of  dye- 
stuff.     The  dye  solution  is  then  added  continuously  while  the  warps  are 
running  and  the  temperature  of  the  bath  should  be  raised  after  each  end. 

In  applying  tannin  and  tartar  emetic  to  cotton  piece-goods,  either  the 
padding  machine  or  jigger  will  be  found  convenient.  The  tannin  bath  is 
started_at  th£_  boil  in  the  jigger  and  the  goods  are  run  for  an  hour  in  the 
cooling  bath.  The  tartar  emetic  may  also  be  applied  in  an  open  soaper  or 
washer.  If  the  padding  machine  or  jigger  is  used,  two  ends  are  given, 
half  of  the  tartar  emetic  solution  being  added  for  each  end.  The  dyeing 
is  usually  carried  out  in  the  jigger  in  a  rather  dilute  solution,  and  with  the 
addition  of  acetic  acid  or  alum.  The  first  end  is  usually  given  cold  and 
without  any  addition  of  dyestuff,  after  which  the  dye  solution  is  gradually 
fed  in  and  the  temperature  of  the  liath  raised  slowly  to  160°  F.,  or  200°  F. 

The  basic  dyes  are  not  well  adapted  to  the  dyeing  of  cops  or  package 
goods  in  dyeing  machines  on  account  of  the  numerous  operations  involved 
and  the  bad  penetrating  and  leveling  properties  of  the  basic  dyes  under  such 
conditions.  Wlien  such  a  method  of  dyeing  is  desired,  however,  the  tannin 
bath  should  be  circulated  hot  and  should  contain  a  small  amount  of  soluble 
oil  (1  pint  of  Monopol  Oil  per  100  gallons)  in  order  to  obtain  penetration 
and  uniformity.  After  tanning,  the  cops  should  be  hydro-extracted  in 
order  to  remove  the  excess  of  liquor,  and  then  treated  with  the  tartar 
emetic  solution  at  140°  F.  After  this  the  goods  should  be  treated  with 
a  dilute  soap  solution  and  then  dyed.  The  dyeing  should  be  started  cold 
and  either  acetic  acid  or  alum  is  added  to  the  dyebath;  the  addition  of 
dyestuff  solution  must  be  regulated  with  care  in  order  to  obtain  uniform 
results;   also  the  rise  in  temperature  must  be  very  gradual.     It  must  be 


274 


PRINCIPAL  BASIC  DYES 


borne  in  mind  that  the  cops  (or  other  package  goods)  act  as  a  filter  on  the 
various  solutions  which  are  circulated  through  the  cotton,  and  conse- 
quently any  imperfectly  dissolved  material  will  be  deposited  in  the  outside 
layers  of  the  cop  and  thus  give  shaded  dyeings. 

3.  Experimental.  Exp.  97.  Principal  Basic  Dyes  on  Cotton. — Use  tost  skeins  of 
cotton  yarn  mordanted  in  the  manner  described  in  Exp.  92  with  4  per  cent  of  tannin 
and  2  per  cent  of  tartar  emetic.  Prepare  the  dyebath  with  2  per  cent  of  alnm  and  the 
dyestuffs  given  below;  enter  at  100°  F.,  gradually  raise  the  temperature  to  180°  F.,  and 
dye  at  that  point  for  one-half  hour;  wash  well  and  dry. 


2  per  cent  Bismarck  Brown. 

2  per  cent  Safranine. 

2  per  cent  Brilliant  Green. 

2  per  cent  New  Methylene  Blue  BB. 

2  per  cent  Tannin  Orange  R. 


2  per  cent  Victoria  Blue  B. 
1  per  cent  Rhodamine. 

1  per  cent  Brilliant  Phosphine. 

2  per  cent  Acridine  Red. 
2  per  cent  Irisamine. 


Test  five  of  these  colors  for  fastness  to  light,  washing,  and  crocking. 
RECORD    OF    RESULTS    OF    TESTS 


Tests. 

1 

2 

3 

4 

5 

Light 

Exp.  98.  Principal  Basic  Dyes  on  Silk. — Use  a  dyebath  containing  5  per  cent  of 
soap  and  slightly  acidify  by  the  addition  of  sufficient  acetic  acid.  Enter  the  silk  at  about 
100°  F.,  and  gradually  raise  to  190°  F.,  and  dye  at  that  temperature  for  one-half  hour. 
Wash  well,  and  brighten  by  passing  the  dyed  skeins  through  a  bath  of  dilute  acetic 
acid,  squeezing  and  diying  without  washing.     Use  the  following  dyestuffs: 


J  per  cent  Diamond  Fuchsine. 

2  per  cent  Diamond  Fuchsine. 

3  per  cent  Safranine. 

J  per  cent  Methylene  Blue. 
2  per  cent  IMethylene  Blue. 


rreen. 


Test  five  of  these  colors  for  fastness  to  water. 


1  per  cent  Auramine. 

2  per  cent  Malachite  Gieeu. 
2  per  cent  Bismarck  Brown. 
5  per  cent  Rhodamine. 

2  per  cent  Tannin  Orange  R. 


RECORDS    OF    RESULTS    OF    TESTS 


Tests. 


Test  to   water 


Steeping  water. 

White  silk 

White  cotton .  . 


CHAPTER   XIII 
APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

1.  The  Substantive  Dyestuffs. — These  coloring  matters  were  first 
discovered  by  Boettiger  in  1884  in  the  dyestuff  known  as  Congo  Red. 
They  are  distinguished  by  the  common  property  of  dyeing  the  vegetable 
fibers  in  full  and  comparatively  fast  shades  without  the  intervention  of 
mordants;  they  also  dye  the  animal  fibers,  wool  and  silk.  Their  chief 
application,  however,  is  to  cotton.  At  present  there  are  several  distinct 
classes  of  substantive  dyes  as  far  as  their  chemical  constitution  is  con- 
cerned,* but  for  the  most  part  they  are  derived  more  or  less  directly  from 
the  parent  substance  benzidine,  and  are  characterized  by  being  "  tetrazo  " 
compounds;  that  is  to  say,  their  molecule  contains  the  azo  group  N  =  N 
twice.  As  benzidine  is  a  diamine  compound  (that  is,  contains  the  amine 
group,  NH2,  twice)  these  colors  are  also  known  as  the  "  diamine  "  colors,  f 

There  are  also  a  number  of  substantive  dj^es  prepared  from  complex 
sulphuretted  bases,  of  which  Primuline  is  the  type. 

The  substantive  colors  as  a  class  are  very  soluble  in  water,  and  when 
using  them  it  is  not  so  particular  to  employ  soft  water  as  when  using  the 
basic  dyes.  It  is  not  well,  however,  to  use  a  very  hard  water  either  for 
dissolving  the  color  or  preparing  the  dyebath.  If  only  hard  water  is  avail- 
able it  should  first  be  boiled  up  with  some  soda  ash  before  the  addition  of 
the  dj^estuff.     In  preparing  the  dyebath  with  substantive  colors  it  is  fre- 

*  According  to  Green's  classification  the  substantive  cotton  dyes  include  five  groups 
from  a  chemical  point  of  view,  as  follows: 

Class  Example 

Disazo  dyes  Benzopurpurine  4B 

Trisazo  dyes  Titan  Black  FF 

Tetrakisazo  dyes  Toluylene  Brown  R 

Stilbene  dyes  Mikado  Orange 

Thiazole  dyes  Primuline 

t  The  substantive  dyes  include  derivatives  of  benzidine,  tolidine,  diamidostilbene, 
and  various  azoxydiamines;  they  also  include  certain  derivatives  of  stilbene  (from  nitro- 
toluene  sulphonic  acid),  such  as  the  Mikado  colors,  Stilbene  Yellow,  etc.  Another  class 
of  direct  cotton  or  substantive  dyes  is  not  included  in  the  azo  dyes  at  all,  but  is  derived 
from  certain  bases  made  from  sulphur  compounds  of  paratoluidine  or  its  homologues; 
these  form  the  Primuline  group  of  dyes. 

275 


276  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

qiiently  the  practice  of  the  dyer  to  add  the  dj'-estuff  directly  to  the  bath; 
while  it  is  frequentlj^  possible  to  do  this  without  bad  results,  nevertheless 
it  is  not  to  be  recommended  for  general  practice,  as  it  is  always  best  to 
first  properly  dissolve  the  dyestuff  and  then  use  the  solution  for  additions 
to  the  bath.  If,  however,  the  dyestuff  is  added  directly,  it  is  always  best 
to  first  add  the  soda  ash,  then  the  dycstufif,  and  finally  the  salt. 

2.  Use  of  Substantive  Dyes  on  Cotton. — The  nature  of  the  dyeing 
process  with  regard  to  the  substantive  colors  on  cotton  is  not  as  yet  thor- 
oughly understood;  unlike  the  dj^eing  of  the  acid  and  liasic  colors,  there 
appears  to  be  no  reason  for  assuming  that  a  chemical  reaction  occurs 
between  the  fiber  and  the  dj^estuff.  It  seems  to  be  simply  a  case  of  the 
absorption  of  the  coloring  matter  by  the  substance  of  the  fiber,  and  though 
the  color  is  withdrawn  from  the  solution  and  fixed  bj'  the  cotton  with  con- 
siderable stability,  yet  it  may  be  redissolved  from  the  fiber  by  repeatedly 
boiling  in  water.  It  is  said  that  if  two  skeins  of  cotton  j^arn,  the  one  dyed 
with  a  substantive  color  and  the  other  undj-ed,  are  boiled  together  in  water 
for  a  long  time,  the  two  skeins  will  eventually  become  dyed  the  same  color. 

The  substantive  dj^es  as  a  rule  are  verj'  soluble  in  water,  and  conse- 
quently the  dj'ebaths  are  seldom  completelj^  exhausted  even  when  rela- 
tively small  amounts  of  the  coloring  matter  are  used.  Cotton  which  has 
been  dyed  with  a  substantive  color  will  also  usuallj'  bleed,  or  have  some  of 
its  color  extracted  again  when  boiled  in  fresh  water;  and  this  extraction  of 
color  may  be  successively  repeated  imtil  a  large  part  of  the  dyestuff  has 
been  removed  from  the  fiber.  Again,  the  amount  of  coloring  matter  which 
can  be  taken  up  by  the  cotton  fiber  appears  to  be  rather  limited,  on  which 
account  very  heavy,  dense  shades,  as  a  rule,  cannot  be  obtained  with  the 
substantive  colors  on  cotton.* 

By  the  addition  of  salt  to  the  dj^ebath  the  solubility  of  the  coloring 
matter  in  the  water  is  lessened,  and  consequently  more  of  the  color  is  forced 
on  the  cotton;  this  condition  is  also  favored  by  employing  as  "short" 
a  bath  as  possible,  that  is,  one  containing  a  minimum  amount  of  dj'e  liquor. 
Either  common  salt  (sodium  chloride)  or  glaubersalt  (sodium  sulphate) 
may  be  used  in  the  dyeljath,  though  the  former  is  mostly  used,  as  it  is 
anhydrous  and  does  not  require  such  a  large  amount  to  be  added.  In 
common  practice  about  20  per  cent  of  salt  is  used  in  the  bath,  though  when 
it  is  desired  to  obtain  heavy  shades  or  to  get  a  better  degree  of  exhaustion 

*  By  mordanting  cotton  with  tannate  of  tin  the  reactivity  of  the  fiber  with  substan- 
tive dj'es  is  much  decreased.  This  fact  is  the  basis  of  the  so-called  method  of  "  resist  " 
dyeing  for  cotton  goods.  Cotton  yarn  prepared  with  tannate  of  tin  is  woven  in  pattern 
effect  with  untreated  j'^arn.  The  cloth  is  then  dyed  with  substantive  colors  and  two- 
color  effects  are  thus  obtainable.  The  tannate  of  tin  is  obtained  on  the  fiber  by  first 
mordanting  the  cotton  with  tannin  and  then  treating  with  a  bath  containing  stannic 
chloride. 


DENSITY  OF  DYEBATH 


277 


larger  amounts  of  salt  may  be  used,  even  to  as  high  as  100  per  cent  on  the 
v/eight  of  the  cotton  being  dyed.  If  too  great  an  amount  of  salt  is  added 
there  will  be  danger  of  some  of  the  dyestuff  being  precipitated  or  "  salted 
out";  this,  however,  as  a  rule  will  not  occur  until  about  1  lb.  of  salt  per 
gallon  of  solution  has  been  added,  an  amount  which  will  hardly  ever  be 
used  in  practice.  When  the  dye  liquor,  however,  is  employed  as  a  standing 
bath,  care  must  be  had  that  in  the  successive  additions  of  dyestuffs  and 
salt  the  accumulation  of  the  latter  in  the  bath  does  not  become  too  great. 
In  order  to  control  this  amount  the  density  of  the  liquor  should  be  deter- 


""««l(2ui 


"^^i^mmimmfHimi:;:^' 


Fig.  160. — Sample  Dyeing  Machine  for  Cops  and  Tubes.     (Pornitz.) 

mined  with  a  hydrometer.  For  light  shades,  as  a  rule,  but  little  salt  is 
used,  and  as  only  a  slight  proportion  of  color  remains  in  the  bath,  the 
liquors  are  seldom  kept  for  further  use.  For  medium  shades  the  best 
density  of  the  dye  liquor  is  about  2°  Tw.,  and  for  dark  shades  from  4  to 
6°  Tw.  In  determining  the  density  of  the  liquor  with  the  hydrometer,  a 
small  portion  should  be  taken  from  the  vat  and  allowed  to  cool  before  being 
tested.*  When  dyeing  in  baths  containing  a  large  amount  of  salt,  it  is 
best  not  to  add  the  salt  until  towards  the  end  of  the  operation,  and  the 
goods  after  coming  from  the  dyebath  should  be  well  rinsed  in  fresh  water, 
otherwise  the  salt  may  crystallize  in  the  material  and  afterwards  be  more 
difficult  to  remove. 

*  The  densities  given  refer  to  those  based  on  a  temperature  of  60°  F.     The  density 
of  the  hot  or  boihng  liquor  will  be  considerably  less  for  the  same  content  of  salt. 


278  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

Increased  exhaustion  of  the  dyebath  may  also  be  o])tained  by  using;  vats 
heated  with  closed  steam  coils,  as  the  introduction  of  live  steam  into  the 
bath  considerably  dilutes  it.  Increased  exhaustion  is  also  obtained  by 
allowing  the  color  to  feed  on  the  cotton  from  a  cooling  bath;  that  is  to  say, 
the  cotton  should  not  be  taken  from  the  bath  at  a  boil,  but  the  steam 
should  be  turned  off  and  the  bath  allowed  to  cool  down  with  the  cotton  in  it. 

As  the  substantive  colors  are  so  soluble  in  water  and  exhaust  so  poorly, 
it  will  seldom  occur  that  they  will  d^^e  unevenlj';*  if  such,  however, 
does  happen,  they  may  be  easily  leveled  by  continued  working  in  a 
boiling  bath. 

It  may  happen,  however,  that  in  dyeing  very  delicate  shades,  especially 
on  a  bleached  bottom,  the  color  will  show  a  tendency  to  come  up  uneven. 
Under  these  circumstances  it  is  advisable  to  reduce  the  amount  of  salt 
added  to  the  dyebath,  or  even  to  omit  it  entirely.  Greater  evenness 
can  also  be  obtained  by  dyeing  in  a  soap  bath,  or  with  the  addition  of  Tur- 
key-red oil,  recovered  oil,  or  other  soluble  oil  preparations  suitable  for 
cotton  djxing.  The  presence  of  the  oil  leads  to  better  penetration  and 
more  even  distribution  of  the  color.  Even  dyeing  is  also  promoted  by 
slowly  feeding  on  the  color  in  a  comparative!}^  cool  dj'ebath  (140  to 
160°  F.).  The  use  of  soluble  oil  is  especiallj^  recommended  when  d3'eing 
delicate  colors  on  mercerized  cotton  or  artificial  silk. 

A  large  number  of  the  substantive  dyes  are  capable  of  forming  lakes 
with  many  of  the  basic  colors,  and  this  property  is  utilized  in  a  practical 
manner  in  the  dyeing  of  many  heavy  and  bright  compound  shades  on 
cotton,  where  the  fiber  is  first  dyed  wdth  a  substantive  color  and  subse- 
quent h'  topped  off  with  a  basic  dye.  The  method  is  especially  useful  for  the 
production  of  bright  greens  and  blues.  These  lakes  are  fairly  permanent 
to  washing,  though  many  are  decomposed  by  boiling  water. 

IManj'  of  the  substantive  dyes  appear  to  work  somewhat  better  when 
the  bath  is  made  slightly  alkaline  f  b}'  the  addition  of  soda  ash,  sodium 
phosphate,  sodium  silicate,  borax,  soap,  etc.|     Just  w'hat  is  the  action 

*  In  dyeing  mercerized  cotton  with  substantive  dyes,  on  account  of  the  much  greater 
affinity  of  the  fiber  for  the  dye,  the  color  is  sometimes  uneven,  so  it  is  well  to  use  less  salt 
or  dye  in  a  soap  bath.  If  the  mercerized  cotton  has  been  dried  unevenl}',  it  will  nearly 
always  come  up  uneven. 

t  Certain  sub-stantive  dyes,  like  Rosophenine  4B  require  the  use  of  a  strongl}'  alkaline 
bath,  adding  twice  the  weight  of  caustic  soda  as  of  dyestuff,  and  using  also  a  large 
amount  of  salt  (100  to  140  per  cent). 

t  In  using  an  alkali  such  as  soda  ash  in  the  bath  with  the  substantive  colors  it  must 
be  remembered  that  this  increases  the  solubility  of  the  dyestuff  and  this  may  lead  to  a 
disadvantage  in  that  after  dyeing  if  the  goods  are  allowed  to  lie  around  in  the  wet  state 
the  color  may  drain  from  one  portion  of  the  material  to  another  and  thus  give  rise  to 
uneven  or  shaded  dj'eings.  This  defect  becomes  more  pronounced  if  soda  ash  is  used 
than  when  it  is  omitted.  In  some  cases  where  the  dye  is  not  very  soluble  (as  with  Dia- 
mine Brown  M)  the  use  of  soda  ash  is  beneficial;  this  is  also  true  in  the  dyeing  of  heavy 


DISSOLVING  SUBSTANTIVE  DYES  279 

of  the  alkali  in  this  case  is  uncertain ;  it  probably  aids  in  the  penetration  of 
the  coloring  matter  into  the  fiber.  For  light  shades  it  is  sometimes  bene- 
ficial to  add  TurkeiM-ed-oil  to  the  ])ath.  In  preparing  the  dyebath  in 
practice,  it  is  best  to  first  add  the  alkali  (if  such  is  used),  then  the  color 
solution,  and  finally  the  salt. 

The  substantive  colors  should  be  dissolved  in  boiling  water,  and  if 
possible,  water  from  condensed  steam  should  be  used.  If  the  water  to  be 
used  for  dissolving  the  dyestuff  is  calcareous,  it  is  best  first  to  boil  the 
water  up  with  an  amount  of  soda  ash  equivalent  to  the  weight  of  the  dye- 
stuff  to  be  dissolved.  After  dissolving  the  color,  the  solution  should  be 
strained  through  a  piece  of  cotton  cloth  or  fine  sieve.  When  the  dyestuff 
is  added  in  an  undissolved  condition  directly  to  the  dyebath,  some  soda  ash 
should  first  be  added,  the  bath  boiled  up,  and  then  the  dyestuff  added, 
after  which  the  salt  is  added. 

Where  hard  water  must  be  used  in  dyeing  substantive  colors,  it  should 
always  first  be  corrected  by  treatment  with  a  suitable  amount  of  soda  ash. 
With  certain  colors  which  are  especially  sensitive  to  hard  water,  it  is  rec- 
ommended to  dye  with  addition  of  2  to  4  per  cent  of  acid  potassium  oxa- 
late, the  amount  depending  on  the  hardness  of  the  water  and  the  quantity 
of  dyestuff  to  be  used ;  it  should  be  noted  that  an  excess  of  the  oxalate  is 
injurious,  causing  the  color  to  exhaust  badly  and  giving  dull  shades. 

It  is  a  mistake  to  suppose  that  the  substantive  dyes  require  a  vigor- 
ously boiling  bath  for  dj^eing;  while  it  is  true  that  a  boiling  bath  will  give 
a  better  penetration  of  color,  it  is  also  a  fact  that  the  amount  of  color 
absorbed  by  the  cotton  is  greater  when  the  temperature  of  the  bath  is 
under  the  boil,  and  it  has  already  been  pointed  out  that  a  better  degree  of 
exhaustion  is  obtained  by  allowing  the  goods  to  remain  for  some  time  in 
the  cooling  bath.  When  desirable,  most  of  the  substantive  colors  may  be 
dyed  at  moderate  temperatures,  and  even  cold.*     In  such  cases  it  is  best 

fabrics  and  tightly  twisted  yarns  where  it  is  desired  to  obtain  good  penetration  of  color. 
In  the  dyeing  of  Chrysamine  it  is  necessary  to  use  sodium  phosphate  to  develop  the 
proper  shade  of  the  color,  and  it  does  not  seem  that  other  alkalies  will  serve  the  same 
purpose. 

*  The  best  temperature  for  dyeing  the  substantive  colors  on  cotton  varies  consider- 
ably with  the  different  dyes.  While  Chrysophenine,  for  example,  will  dj^e  practicality  a 
full  shade  at  100°  F.,  Benzo  Fast  Scarlet  4BS  is  hardly  taken  up  by  the  fiber  at  all  until 
140°  F.  is  reached.  Owing  to  the  difference  in  the  amount  of  absorption  of  the  colors 
by  the  cotton  at  different  temperatures  it  will  be  seen  that  in  dyeing  successive  lots 
with  compound  shades  where  a  mixtdre  of  several  dyes  is  used  considerable  trouble 
in  matching  may  be  caused  unless  the  temperature  conditions  are  maintained  the  same. 
In  using  mixtures  of  dyes  for  compound  shades  it  is  always  advisable  to  select  those  which 
possess  appro.ximately  the  same  dyeing  qualities,  and  it  is  always  better  to  have  colors 
which  are  very  soluble  than  those  which  are  difficultly  soluble.  This  is  especially  true  if 
the  d3'es  are  to  be  employed  for  shading  purposes;  that  is  to  say,  for  addition  towards  the 
end  of  the  dyeing  in  order  to  throw  the  shade  to  the  desired  tone,  as  these  dyes  are  usually 
added  directly  to  the  boiling  dyebath. 


280  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

to  add  to  the  bath  some  soap  or  Turkey-red  oil  in  order  to  obtain  better 
penetration  of  the  coloring  matter.  When  dyeing  in  a  cold  bath  it  is 
sometimes  recommended  to  mix  the  dyestuff  first  with  its  own  weight  of 
caustic  soda  solution  (76°  Tw.),  then  dissolve  in  a  sufficient  quantity  of 
hot  water,  and  add  this  solution  to  the  dyebath  along  with  a  little  soap.* 

For  dyeing  light  shades f  for  each  100  lbs.  of  cotton  yarn  about  200 
gallons  of  water  should  be  used,  while  for  dark  shades  the  amount  of  ^-ater 
should  be  limited  to  about  130  gallons.  For  dark  shades,  especially  where 
only  one  dyestuff  is  used  in  the  color,  the  yarn  can  usually  be  entered  at 
the  boil;  for  lighter  shades,  and  where  several  dyes  may  be  used  in  com- 
bination, it  is  best  to  enter  the  cotton  at  140  to  160°  F.,  and  gradually 
raise  to  the  boil.  If  any  tendency  towards  unevenness  is  observed,  it  is 
best  to  add  only  a  part  of  the  salt  to  the  bath  at  first  and  reserve  the  rest 
to  be  added  near  the  end  of  the  dyeing.  Yarn  which  has  been  dyed  in 
light  shades  is  not  generally  rinsed  after  dyeing  unless  alkali  has  been  used 
in  the  bath ;  but  where  heavy  shades  are  obtained  the  yarn  should  always 
be  well  rinsed  in  order  to  remove  all  excess  of  residual  dye  liquor  and  salt 
solution. 

The  fastness  and  quality  of  the  colors  produced  with  the  substantive 
dyes  vary  greatly  with  the  individual  dyestuff,  and  no  general  rule  in 

*  The  following  is  a  list  of  suitable  dyestufTs  for  use  in  a  cold  bath: 

Benzo  Azurine  G  Diamine  Heliotrope 
Brilliant  Azurine  oG  Diamine  Orange 
Brilliant  Orange  G  Diamine  Red  lOB 
Brilliant  Purpurine  Diamine  Rose 
Chicago  Blues  Diamine  Sky  Blue  FF 
Chrj'sophenine  Diamine  Yellow  CP 
Columbia  Black  Diaminogene  B 
Columbia  Blue  G  &  R  Erica  BN  &  GN 
Columbia  Green  Erie  Blue 
Congo  Brown  "                       Heliotrope  BB 
Congo  Rubine  Orange  TA 
Cosmos  Red  Oxamine  Black 
Cotton  Brown  Oxamine  Blue 
Cotton  Red  Oxamine  Brown 
Cotton  Rubine  Oxamine  Claret 
Cotton  Yellow  Oxamine  Fast  Red 
Curcumine  S  Oxydiamine  Yellow 
Diamine  Black  BH  Pyramine  Orange 
Diamine  Blue  Pj-ramine  YeUo<7 
Diamine  Brown  M  &  S  Thioflavine 
Diamine  Fast  Yellow  Zambesi  Blue  BX 
t  In  the  dyeing  of  light  shades  bleached  cotton  should  nearly  always  be  used  if  clear 
bright  tones  of  color  are  desired.     As  bleached  cotton  is  somewhat  liable  to  dj'e  up  un- 
evenly, the  dyeing  should  be  done  in  a  boiling  soa]i  bath,  or  one  containing  soluble  oil. 
This  is  particularly  true  of  very  light  shades  of  sky  blue,  flesh,  pink,  etc.     No  salt  should 
be  added  to  the  bath. 


AFTER-TREATING  SUBSTANTIVE   DYES  281 

this  respect  can  be  formulated.  On  account  of  their  great  solubility,  how- 
ever, they  are  very  liable  to  bleed  on  washing,  and  in  many  cases  they  are 
sensitive  to  the  action  of  acids.  In  fastness  to  light  they  vary  greatly, 
while  some  are  quite  fugitive,  others  are  very  fast;  in  general,  however, 
they  are  as  fast  as  the  basic  dyes  in  this  respect.* 

3.  After-treatment  of  the  Substantive  Dyes. — A  number  of  the  sub- 
stantive colors  show  a  greater  degree  of  fastness  to  washing  and  light 
when  after-treated  with  solutions  of  metallic  salts,  j     Chrome  and  blue- 

*  The  substantive  d3'es  cover  a  great  range  in  their  qualities  of  fastness;  Congo  Red, 
for  example,  is  very  sensitive  to  acids,  whereas  Benzo  Fast  Scarlet  4BS  is  exceedingly- 
fast  to  acids.  Primuline,  on  the  one  hand,  has  very  poor  fastness  to  light,  while  Chlorazol 
Fast  Yellow  B  is  exceedingly  fast  in  this  respect. 

t  Hiibner  summarizes  the  methods  for  applying  substantive  dyes  to  cotton  as  fol- 
lows: 

1.  Dyed  direct. 

2.  Dyed  direct,  then  diazotized  and  developed  with  various  developers. 

3.  Dyed  direct  and  coupled  with  diazotized  paranitraniline. 

4.  Dyed  direct  and  after-treated  with  bichromate;  the  material  should  be  well 
rinsed  after  dyeing  and  treated  for  one-half  hour  at  the  boil  with  2  to  3  per  cent  of  either 
potassium  or  sodium  bichromate,  with  or  without  the  addition  of  a  small  quantity  of 
acetic  acid. 

5.  Dyed  direct  and  after-treated  with  copper  sulphate;  the  material  is  well  rinsed 
and  treated  for  one-half  hour  at  120°  F.  with  1  to  4  per  cent  of  copper  sulphate  and  1  to  2 
per  cent  of  acetic  acid.  Basic  dyes  may  be  added  to  the  copper  bath  for  purposes  of 
shading,  in  which  case  the  cotton  should  be  entered  cold,  and  the  bath  gradually  heated 
to  140°  F.  The  after-treatment  with  copper  sulphate  improves  the  fastness  to  washing, 
but  more  especially  the  fastness  to  light.  Salts  of  nickel  and  cobalt  may  also  be  used 
for  the  same  purpose,  but  as  they  have  no  better  effect  than  copper  sulphate  and  are 
much  more  expensive,  their  use  is  not  practical. 

6.  Dyed  direct  and  after-treated  with  bluestone  and  chrome;  use  1  to  3  per  cent  of 
chrome,  1  to  3  per  cent  of  bluestone  and  1  to  3  per  cent  of  acetic  acid,  for  one-half  hour 
at  140  to  200°  F.  This  treatment  increases  the  fastness  to  washing  more  than  the 
preceding  one  and  also  increases  the  fastness  to  light.  After  the  treatment  the  cotton 
should  be  well  rinsed  and  if  necessary  soaped  to  neutralize  excess  of  acid  and  to  soften 
the  goods. 

7.  Dyed  direct  in  a  bath  without  addition  of  soda. 

S.  Dyed  direct  and  after-treated  with  formaldehyde;  treat  for  fifteen  to  twenty 
minutes  at  120  to  240°  F.,  or  for  one-half  hour  in  a  cold  bath  with  5  to  3  per  cent  of 
formaldehyde  (40  per  cent),  using  also  2  to  3  per  cent  of  acetic  acid.  This  increases  the 
fastness  to  washing  of  some  dyes. 

9.  Dyed  direct  and  after-treated  with  Solidogen;  prepare  the  bath  with  2  per  cent 
of  hydrochloric  acid  and  2  to  6  per  cent  of  Solidogen  (Hochst),  and  treat  for  one-half 
hour  in  the  boiling  bath. 

10.  Dyed  direct  and  after-treated  with  chromium  fluoride  or  chrome  alum;  this 
improves  the  fastness  to  washing.  Treat  for  one-half  hour  at  140  to  200°  F.  with 
2  to  4  per  cent  of  chromium  chloride  (20°  Be.)  or  2  to  4  per  cent  of  chromium  fluoride 
and  2  to  3  per  cent  acetic  acid,  or  4  to  5  per  cent  of  chrome  alum  and  2  to  3  per  cent 
acetic  acid. 

11.  Dyed  direct  and  developed  with  bleaching  powder  solution;  this  is  limited 
almost  exclusively  to  Primuline.     Treat  for  one-quarter  hour  at  70°  F.  in  a  bath  con- 


282  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

stone  are  chiefly  used  for  this  purpose,  the  former  for  increasing  more 
especially  the  fastness  to  washing,  and  the  latter  for  increasing  the  fastness 
to  light.  Not  all  of  the  substantive  dyes  are  capable  of  this  treatment, 
and  even  in  the  case  of  those  with  which  the  process  may  be  used,  the  color 
is  usually  darkened  and  dulled  to  a  marked  degree.  This  fact  has  to  be 
allowed  for  in  the  matching  of  shades,  and  usually  causes  a  good  deal  of 
trouble.  The  after-treatment  is  usually  carried  out  in  a  fresh  bath,  though 
in  cases  where  light  shades  are  being  dyed  and  the  dyebath  is  practically 
exhausted,  the  after-treatment  may  be  effected  directly  in  this  bath. 
Vrhe  amount  of  metallic  salt  to  be  used  varies  with  the  depth  of  shade  dyed, 
from  1  to  3  per  cent  of  either  chrome  or  bluestone  being  used  together  with 
about  the  same  amount  of  acetic  acid.  The  bath  is  run  at  from  140°  F. 
to  the  boil,  though  some  recommend  not  to  go  above  160°  F.  In  some 
cases  a  combined  treatment  with  l)oth  chrome  and  bluestone  is  given. 
In  certain  cases  where  chrome  cannot  he  used  (on  account  of  its  strong 
oxidizing  action)  it  may  be  replaced  by  chromium  fluoride  or  chrome  alum. 
Increased  fastness  to  washing  and  water  may  also  be  given  to  many  of  the 
substantive  colors  b}''  an  after-treatment  with  salts  of  aluminium  (about 
5  lbs.  of  aluminium  acetate  of  4°  Tw.,  4  to  G  ozs.  of  aluminium  sulphate, 
or  8  ozs.  of  alum  per  10  gallons  of  liquor  being  used).  The  goods  are  treated 
at  a  lukewarm  temperature,  and  hydro-extracted  and  dried  without 
further  washing.  \<(By  treatment  with  a  solution  of  formaldehyde  it  has 
been  found  that  increased  fastness  to  washing  may  be  obtained  with  a 
number  of  the  substantive  dyes.  This  is  especially  true  of  some  of  the 
direct  blacks.  The  process  is  carried  out  by  treating  the  dj'ed  goods  for 
one-half  hour  in  a  bath  at  140°  F.  containing  3  per  cent  of  formaldehyde 
(30  per  cent)  and  3  per  cent  of  acetic  acid  (9°  Tw.).  In  some  cases  it  is 
recommended  to  add  about  1  per  cent  of  chrome  to  the  bath,  though  this 
would  seem  to  be  merely  equivalent  to  treating  the  color  with  a  chromium 
salt,  as  formaldehyde  being  a  strong  reducing  agent  and  chrome  a  strong 
oxidizing  agent,  the  two  reacting  with  one  another  woukl  produce  a  chro- 
mium salt  in  the  bath  with  the  loss  of  the  formaldehyde.* 

taining  one-half  gallon  bleaching  solution  of  15°  Tw.  to  100  gallons  of  water.  This 
gives  a  very  fast  reddish  yellow  color;  by  raising  the  temperature  the  reddish  tone  gives 
place  to  pure  yellow,  but  this  shade  deteriorates  with  age. 

*  The  increase  in  weight  of  cotton  during  dj'eing  is  sometimes  a  consideration  of 
some  importance.  It  must  be  borne  in  mind  in  this  connection  that  when  raw  cotton  is 
treated  with  solutions  of  boiling  water,  especiallj'  if  alkali  is  present,  a  certain  lo.ss  in 
weight  will  be  observed  due  to  the  removal  of  the  gummy  and  pectin  matters  from  the 
fiber.  This  will  usually  amount  to  from  3  to  5  per  cent,  unless  the  cotton  is  bleached 
before  dyeing,  when  the  loss  will  be  larger  owing  to  the  bleaching  process  removing  more 
of  the  impurities.  In  the  dyeing  operation,  of  course,  a  certain  amount  of  dyestuff  is 
fixed  in  the  fiber  and  also  various  mordants,  etc.,  depending  on  the  process  of  dyeing 
employed.  This  naturally  adds  some  weight  to  the  cotton,  and  the  net  increase  in 
weight  will  be  the  difference  between  the  amount  of  materials  taken  up  by  the  fiber 


AFTER-TREATING   SUBSTANTIVE   DYES  283 

-y-^  In  some  cases  an  after-treatment  may  be  given  with  2  to  3  per  cent  of 
pyrolignjieof  iron  (15°  Tw.)-  This  renders  the  shade  duller  and  is  chiefly 
useTon  dark  blues  and  blacks. 

To  increase  the  fastness  to  washing  it  has  also  been  suggested  to  give 
an  after-treatment  with  magnesium  sulphate,  followed  by  a  passage 
through  a  weak  solution  of  caustic  soda.*  Some  red  dyes  may  be  made 
faster  by  adding  a  small  quantity  of  sodium  stannate  to  the  caustic  soda 
bath,  this  is  especially  true  of  Benzo  Fast  Scarlet,  which,  under  such  con- 
ditions gives  a  red  color  almost  as  fast  as  a  diazotized  and  developed  red. 
^Another  method  of  after-treatment  which  also  weights  the  cotton  to 
some  extent  (as  well  as  increasing  the  fastness  of  the  color  to  washing), 
is  to  pass  the  cotton  through  a  tannin  bath  and  subsequently  fix  with 
pyrolignite  of  iron.  Of  course,  this  is  only  suitable  for  blacks  or  other 
dark  colors. 

Some  of  the  substantive  dyes  (such  as  Congo  Red  and  Benzopurpurine) 
are  very  sensitive  to  the  action  of  acids,  and  in  dyeing  these  colors  it  is 
often  useful  to  give  them  an  after-treatment  in  a  bath  containing  soda 
ash  (5  per  cent),  as  with  this  treatment  the  color  is  apt  to  change  less  on 
exposure. 

Black  colors  are  often  given  an  after-treatment  in  a  lukewarm  dilute 
soap  bath  containing  also  a  little  olive  oil,  as  this  gives  the  black  a  deeper 
and  more  beautiful  tone.  Blacks  with  substantive  dyes  which  are  after- 
treated  with  chrome  and  bluestone,  may  also  have  this  after-treatment 

and  the  loss  due  to  removal  of  impurities.  In  the  case  of  substantive  colors  the  weight 
of  the  cotton  is  generally  very  little  altered  by  the  dyeing;  with  the  sulphur  colors  the 
weight  is  somewhat  increased,  especially  in  the  case  of  Sulphur  Blacks;  basic  dyes,  owing 
to  the  mordant  of  tannin  and  antimony,  will  also  increase  the  weight  from  2  to  5  per  cent. 
With  Aniline  Black  and  Turkey  Red  the  weighting  amounts  to  as  much  as  10  per  cent.  It 
is  sometimes  desirable  to  increase  artificially  the  weight  of  dyed  cotton  goods.  In  the 
case  of  piece  dyeing  this  is  readily  effected  in  the  finishing  of  the  cloth  by  using  starch 
sizes  and  mineral  filling;  but  in  the  case  of  yarns  and  knit  goods  where  such  methods  of 
finishing  are  not  available  other  methods  must  be  adopted  in  which  the  fiber  must 
absorb  the  weighting  material.  Magnesium  sulphate  (Epsom  salts)  is  generally  used 
for  this  purpose,  as  follows  (Cassella) :  For  100  lbs.  of  cotton  yarn  or  knit  goods,  use  a 
bath  of  160  gallons  of  water  containing  100  lbs.  of  magnesium  sulphate,  16  lbs.  of  dex- 
trine and  4  lbs.  of  rape-seed  oil  saponified  with  1  lb.  of  soda.  The  goods  are  steeped  for  a 
short  time  in  the  lukewarm  bath,  then  hydro-extracted  and  dried.  An  increase  in 
weight  of  8  to  10  per  cent  can  be  obtained.  Instead  of  using  rape-seed  oil  and  soda, 
sometimes  glycerin  is  added,  as  the  presence  of  this  in  the  fiber  causes  a  greater  absorp- 
tion of  moisture.  For  weighting  yarns  or  goods  dyed  with  substantive  black  colors,  a 
treatment  with  tannin  and  iron  salts  may  be  resorted  to,  as  this  not  only  increases  the 
weight,  but  also  adds  to  the  depth  of  the  color.  The  goods  are  steeped  for  several  hours 
in  a  bath  containing  15  to  20  per  cent  of  sumac  extract,  squeezed  and  treated  in  a  bath 
of  pyrolignite  of  iron  standing  at  3  to  5°  Tw.,  then  rinsed  and  dried.  By  this  method 
an  increase  in  weight  of  about  7  per  cent  can  be  obtained. 

*See  W.  Warr,  Brit.  Pat.  25,165  of  1904  {Jour.  Soc.  Dyers  &  Col.,  1905,  p.  118). 


284  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

combined  with  a  process  for  the  production  of  a  one-bath  Anihne  Black; 
the  substantive  dye  in  this  case  forming  a  good  bottom  color  for  the  Aniline 
Black.  The  process  is  capable  of  yielding  a  very  fine  black  fast  to  rubbing 
and  acids  and  also  giving  a  softer  fiber  than  when  dyed  with  Aniline  Black 
alone  by  the  usual  process. 

4.  Topping  Substantive  Colors  with  Basic  Dyes. — It  has  already  been 
stated  that  the  substantive  dyes  do  not  produce  very  bright  or  brilliant 
shades  on  cotton,  at  least  not  comparing  in  this  respect  with  the  basic 


Fig.  161.— Piece  Dye  Kettle.     (Jas.  Hunter  Machine  Co.) 

and  acid  dyes.*  It  has  been  found  possible,  however,  to  improve  very 
materially  the  brilliancy  of  the  color  by  topping  with  a  small  quantity  of  a 
basic  dye,  using  a  separate  bath.  The  substantive  color  appears  to  act 
as  a  mordant  for  the  basic  dye,  so  that  a  certain  amount  of  the  latter 
becomes  fixed  upon  the  fiber  and  does  not  merely  stain  it,  but  produces 
a  compound  shade  with  the  substantive  color  which  has  good  fastness  co 
washing.     The  fastness  to  washing  may  be  improved  by  an  after-treatment 

*  This  quality,  however,  has  been  greatly  improved  in  some  of  the  more  recently 
discovered  substantive  dyes.  Chlorazol  Brilliant  Blue  and  the  Benzo  Brilhant  Violets, 
for  example,  are  almost  equal  in  brilliancy  to  Methylene  Blue  and  Methyl  Violet. 


TOPPING  WITH  BASIC  COLORS  285 

with  tannin  in  another  bath,  but  this  materially  increases  the  cost  of  the 
process.  Usually  in  this  topping  process  a  basic  dye  of  the  same  general 
color  as  the  substantive  dye  is  used;  as  for  example,  the  cotton  is  first 
dyed  with  a  Direct  Blue  and  then  topped  off  with  a  small  quantity  of 
Methylene  Blue.  This  will  give  a  bright  deep  shade  of  blue  far  surpassing 
the  original  Direct  Blue.  Bright  greens  may  also  be  obtained  by  first  dye- 
ing with  a  Direct  Green  (which  only  gives  a  dull  green  at  best)  and  then 
topping  with  Malachite  Green. 

The  basic  dye,  as  a  rule,  tends  to  be  taken  up  by  the  dyed  cotton 
very  rapidly,  and  uneven  results  will  be  obtained  unless  proper  precautions 
are  taken  in  the  dyeing.  It  is  generally  necessary  to  start  with  a  cold  bath 
and  raise  the  temperature  gradually  to  about  140°  F.,  and  also  to  add  the 
solution  of  the  basic  coloring  matter  in  several  portions  to  the  dyebath 
rather  than  all  at  once.  Furthermore,  in  order  to  retard  the  dyeing  a 
small  quantity  of  acetic  acid  or  alum  should  be  added  to  the  bath, 
as  the  basic  dye  will  go  on  the  fiber  less  rapidly  from  a  slightly  acid 
bath. 

Perhaps  the  fastest  dyeings  by  this  method  are  to  be  obtained  by 
first  dyeing  with  the  substantive  dye  in  a  bath  which  also  contains  2  to  4 
per  cent  of  tannic  acid;  dye  at  the  boil  and  then  allow  to  remain  in  the 
cooling  bath  for  some  time  in  order  to  absorb  the  maximum  quantity  of 
dye  and  tannin;  squeeze  out  and  pass  through  a  fresh  cold  bath  con- 
taining 1  to  2  per  cent  of  tartar  emetic.  Then  wash  well  and  top  in  a 
fresh  bath  with  the  necessary  basic  dye.  For  blacks  or  dark  blues  pyro- 
lignite  of  iron  may  be  used  in  place  of  tartar  emetic. 

5.  Dyeing  Cotton  Warps  in  the  Size. — Cotton  warps  are  sized  usually 
with  paste  mixtures  of  starch,  waxes,  and  China  clay,  for  the  purpose  of 
giving  stiffness  and  protection  to  the  yarn  in  the  process  of  weaving. 
Sometimes  where  great  cheapness  in  ctyeing  is  required  the  dye  is  applied 
to  the  warp  at  the  same  time  with  the  size.  The  size  is  simply  mixed  with 
the  required  dye  solution  and  the  mixture  is  then  padded  on  to  the  warp 
in  a  suitable  machine  provided  with  a  size  box  and  squeeze  rollers.  The 
warps  pass  through  in  rope  form,  and  as  they  are  usually  run  at  good  speed 
(30  to  50  yards  per  minute)  any  portion  of  the  yarn  is  in  contact  with  the 
size  for  a  brief  time  (one-half  to  one  minute)  and  therefore  dyes  must  be 
used  that  will  dye  into  the  fiber  readily.  For  light  shades  one  passage 
is  usually  sufficient,  but  for  heavier  shades  several  runs  may  be  given. 
For  this  character  of  dyeing  the  substantive  dyes  give  the  best  results  and 
are  the  ones  most  extensively  used.  For  brilliant  shades  and  bright  tints 
some  of  the  acid  dyes  may  also  be  used.* 

*  The  following  method  is  recommended  for  the  preparation  of  the  size  for  dyeing: 
100  lbs.  of  wheat  flour  are  stirred  with  water  to  a  thin  paste  in  a  wooden  vessel  fitted 
with  a  stirrer.     This  is  then  stirred  two  to  three  days  until  perfectly  uniform  so  that  no 


286  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

The  dj'ed  size  is  applied  hot  so  as  to  g;ive  as  good  a  penetration  of  color 
as  possible,  but  even  at  the  best  it  will  l3e  easily  recognized  that  this  is  a 
poor  method  of  dyeing  and  is  more  of  the  order  of  coating  the  yarn  with  the 
color.  The  method  is  employed  somewhat  for  dyeing  cotton  warps  used  in 
the  weaving  of  low-grade  shoddy  union  cloths  and  also  for  warps  used  in 
various  ornamental  fabrics  and  backing  yarns  for  rugs  and  carpets.  It  is 
naturally  most  serviceable  in  the  case  of  fabrics  which  are  not  to  be 
washed,  for  such  treatment  would  remove  most  of  the  size  and  also  the 
color. 

The  dyeing  of  hank  yarn  is  also  sometimes  done  in  the  size,  in  which 
case  a  form  of  hank  sizing  machine  is  used  for  apphdng  the  colored  size. 

6.  Experimental.  Exp.  99.  Dyeing  Substantive  Dyes  on  Cotton. — These  dj^es  are 
usually  applied  to  cotton  in  a  neutral  bath  containing  either  common  salt  or  glaubersalt; 
hence,  the  name  of  "  salt  "  or  "  direct  cotton  "  colors  for  this  class  of  dyes.  T)yc  a  skein 
of  cotton  yarn  in  a  bath  containing  300  cc.  of  water,  20  per  cent  of  common  salt,  and  1 
per  cent  of  Congo  Red;  enter  at  140°  F.,  gradually  raise  to  the  boil  and  dye  at  that 
temperature  for  one-half  hour;  then  wash  well  and  dry.  The  bath  does  not  exhaust 
very  well,  but  by  adding  more  salt  towards  the  end  of  the  dyeing  a  better  degree  of 
exhaustion  may  be  obtained,  although  the  colors  are  not  apt  to-  be  so  fast  to  washing. 
The  use  of  the  common  salt  (or  of  glaubersalt)  in  the  bath  is  to  increase  the  exhaustion 
and  give  better  penetration  of  the  color  through  the  fiber.     The  substantive  dyes  give 

more  lumps  are  present.     At  the  same  time  100  lbs.  of  potato  flour  are  treated  in  the 
same  manner,  the  only  difference  being  that  it  becomes  uniform  much  quicker. 

These  two  pastes  are  then  run  together  into  another  vessel  which  is  also  provided 
with  a  stirrer  and  which  is  generally  placed  above  the  sizing  trough.     To  this  mixture 

are  now  added: 

1  lb.  Japanese  wax 
12  lbs.  cocoanut  oil  i 

50  lbs.  magnesium  sulphate 
100  lbs.  China  clay 

This  is  now  diluted  down  to  150  gallons  and  thoroughly  stirred  for  two  to  three  hours. 
It  is  then  boiled  for  one  hour  or  until  the  mi.xture  is  thick  enough.  The  dyestuff  which 
has  first  been  completely  dissolved  is  then  added  and  the  boiling  is  continued  until  the 
size  has  the  correct  feel.  The  whole  or  part  of  it  is  now  run  into  the  sizing  trough  and 
the  dyeing  is  commenced. 

In  addition  to  the  substances  mentioned  above  magnesium  chloride  is  frequently 
added  as  a  weighting  agent,  also  substances  which  help  to  promote  penetration  are 
added  in  small  quantities,  for  example,  Turkey-red  oil. 

The  consistency  of  the  size  differs  in  various  cases;  for  fine  yarns  it  is  required  thinner 
than  for  coarser  yams. 

Of  the  coal-tar  colors  the  substantive  dyes  are  the  most  extensively  used  for  dyeing 
in  the  size.  The  acid  dyes  are  also  employed  for  several  shades  (gray,  blue,  cream, 
white). 

It  has  been  found  by  experience  that  when  working  with  substantive  dj'es  the  50  lbs. 
of  magnesium  sulphate  can  be  suitably  replaced  by  20  to  30  lbs.  of  potash  or  an  equal 
quantity  of  calcined  soda.  For  weighting  50  to  100  lbs.  of  barium  sulphate  can  then  be 
added,  ^^^len  working  with  acid  dyes  one  can  add  20  lbs.  of  magnesium  sulphate  in 
place  of  50  lbs.  and  also  30  lbs.  of  barium  sulphate. 


EXPERIMENTAL  STUDIES  287 

good  colors  on  cotton,  many  of  them  being  fast  to  light,  acids,  and  alkalies,  though  some 
of  them  are  changed  by  treatment  with  acids,  as  is  the  case  with  Congo  Red.  To  show 
this  action,  dip  a  few  strands  of  the  dyed  yarn  plaited  together  into  a  dilute  solution  of 
sulphuric  acid;  it  will  be  found  that  the  red  color  is  changed  to  a  bluish  black.  The 
red  color  may  be  brought  back  by  treatment  with  alkalies,  which  may  be  shown  by  dip- 
ping a  portion  of  the  above  sample  in  a  dilute  solution  of  soda  ash.  Do  this  carefully 
and  then  wash  well  so  that  the  sample  will  show  one-half  discolored  and  the  other  half 
red.  The  chief  defect  of  the  substantive  dyes,  however,  on  cotton,  is  their  liability  to 
bleed  on  washing  in  hot  water  or  soap  solutions.  To  show  this  action,  make  up  two 
plaited  samples  from  the  dyed  skein  together  with  white  cotton  yarn ;  boil  one  of  these 
in  plain  water  for  fifteen  minutes,  then  squeeze  and  dry,  when  it  will  be  found  that  the 
color  has  bled  into  the  white  yarn.  Scour  the  other  sample  in  a  warm  dilute  soap  bath, 
then  wash  in  fresh  water  and  dry,  and  note  if  the  color  has  bled  or  not  into  the  white. 
Exp.  100.  Influence  of  the  Amount  of  Salt  in  the  Dyebath. — Dye  skeins  of  cotton 
yarn  in  baths  containing  3  per  cent  of  Erie  Blue  and  the  respective  amounts  of  com- 
mon salt  as  given  below;  enter  at  160°  F.,  bring  to  the  boil,  and  dye  at  that  temperature 
for  one-half  hour,  then  wash  well  and  dry. 

(1)  Use  no  salt    •  (3)  Use  20  per  cent  of  salt 

(2)  Use  5  per  cent  of  salt  (4)  Use  100  per  cent  of  salt 

Compare  the  depth  of  color  obtained  on  the  several  skeins  and  determine  what  influence 
if  any,  the  amount  of  salt  has  on  the  color  taken  up  by  the  fiber. 

Exp.  101.     Showing  the  Influence  of  the  Temperature  of  the  Dyebath. — Dye  test 
skeins  of  cotton  j^arn  in  a  bath  containing  300  cc.  of  water,  20  per  cent  of  salt,  and  2  per 
cent  of  Benzopurpurine  4B.     Regulate  the  temperature  as  follows; 
^  (1)  Dye   for   one-half   hour   at   the   ordinary   room   temperature,   which    is   about 
60  to  80°" F. 

^  (2)  Enter  cold  and  raise  to  120°  F.,  and  continue  at  that  temperature  for  one-half  hour. 
•y  (3)  Enter  cold  and  raise  to  160°  F.,  and  continue  at  that  temperature  for  one-half 
Viour. 
4  (4)  Enter  cold  and  raise  to  180°  F.,  and  continue  at  that  temperature  for  one-half 
hour. 

^   (5)  Enter  cold  and  raise  to  the  boil  and  continue  at  that  temperature  for  one-half 
hour. 

In  each  case  squeeze  the  excess  of  liquor  from  the  skein  back  into  the  dyebath,  and 
without  further  addition  of  dyestuff  or  salt,  but  simply  diluting  the  bath  to  its  original 
volume  with  water,  dye  a  second  set  of  skeins  in  these  baths  at  the  boil  for  one-half  hour. 
Wash  and  dry.  Compare  the  relative  depths  of  colors  on  the  several  sets  of  skeins  and 
in  this  manner  determine  how  the  temperature  of  the  dyebath  affects  the  exhaustion  of 
the  color. 

Exp.  102.  Use  of  Soda  Ash. — Very  often  a  better  degree  of  exhaustion  of  the  dye- 
bath and  a  greater  fastness  of  the  color  to  washing  may  be  obtained  by  dyeing  sub- 
stantive colors  in  a  bath  made  slightly  alkaline  with  soda  ash.  Dye  a  skein  of  cotton 
yarn  in  a  bath  containing  20  per  cent  of  salt,  1  per  cent  of  soda  ash,  and  2  per  cent  of 
Direct  Green;  enter  at  160°  F.,  gradually  bring  to  the  boil,  and  dye  at  that  tempera- 
ture for  one-half  hour.  Wash  well  and  dry.  In  place  of  using  soda  ash,  which  is  a 
strong  alkali,  milder  alkaline  salts  such  as  sodium  phosphate  *  or  sodium  silicate  may  be 
used. 

*  When  using  sodium  phosphate  from  1  to  3  per  cent  of  the  salt  is  added  to  the  bath. 
Certain  substantive  yellow  and  green  dyes  give  much  brighter  and  purer  colors  when 
dyed  with  this  alkali. 


288  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

Exp.  103.  Use  of  Soap. — This  mothod  is  somewhat  similar  to  the  preceding  one,  ex- 
cept that  soap  is  used  for  making  tlic  bath  alkaUne;  it  is  also  supposed  that  this  makes  the 
color  somewhat  faster  to  washing  with  soap.  Dye  a  skein  of  cotton  yarn  in  a  bath  con- 
taining 5  per  cent  of  soap  and  2  per  cent  of  Direct  Green;  enter  at  160°  F,  gradually 
bring  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour;  wash  well  and  dr>'. 
Salt  cannot  be  used  in  the  bath,  as  it  precipitates  the  soap.  For  comparison  dye  another 
skein  of  cotton  yarn  in  a  bath  with  20  per  cent  of  salt  and  2  per  cent  of  Direct  Green 
in  the  usual  manner;  wash  well  and  dry.  Compare  the  colors  obtained  on  these  skeins 
with  the  one  in  the  previous  experiment ;  also  test  them  for  fastness  to  washing  and  note 
if  the  method  of  dyeing  in  the  alkaline  or  soap  bath  has  increased  the  fastness  of  the 
color  to  any  e.xtont. 

Exp.  104.  After-treatment  with  Chrome. — This  treatment  is  for  the  purpose  of 
increasing  the  fastness  of  certain  substantive  dyes  to  washing  and  acids;  it  also  deepens 
the  color,  a^  a  rule,  to  quite  a  degree,  and  in  some  cases  causes  a  considerable  change  in 
the  tone  of  the  color.  Dye  two  skeins  of  cotton  yarn  together  in  a  bath  containing  20 
per  cent  of  common  salt  and  2  per  cent  of  Chromanil  Brown  2G;  enter  at  160°  F., 
gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour;  wash  well  and 


Fig.  162. — Two-Compartment  Dyeing  Machine.     (Textile-Finishing  Machinery  Co.) 

set  one  of  the  skeins  aside  for  comparicon.  Take  the  second  skein  and  pass  into  a  bath 
containing  2  per  cent  of  chrome;  boil  for  fifteen  minutes,  then  wash  well  and  dry. 
Compare  the  colors  obtained  on  each  of  the  skeins  and  thus  note  the  effect  of  the  after- 
chroming  on  the  color.  Make  tests  on  both  skeins  for  fastness  to  washing  and  perspira- 
tion; also  test  the  colors  for  their  fastness  to  light. 

Exp.  105.  After-treatment  with  Bluestone. — This  treatment  is  usually  for  the 
purpose  of  giving  an  increased  fastness  to  light;  the  color  is  also  generally  considerably 
altered  in  tone  by  the  treatment.  Dye  two  skeins  of  cotton  yarn  together  in  a  bath 
containing  20  per  cent  of  common  salt  and  3  per  cent  of  Diamine  Blue  RW;  enter  at 
160°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour;  wash 
well,  and  set  one  of  the  skeins  aside  for  comparison.  Pass  the  second  skein  into  a  fresh 
bath  containing  .3  per  cent  of  bluestone  and  3  per  cent  of  acetic  acid;  work  for  fifteen 
minutes  at  a  temperature  of  180°  F.,  then  wash  well  and  dry.  Compare  the  color  on 
the  two  skeins,  and  make  a  test  on  each  for  its  fastness  to  light. 

Exp.  106.  Use  of  Formaldehyde  for  Fastening  Substantive  Colors. — This  reagent 
appears  to  increase  the  fastness  of  several  of  the  substantive  colors  on  cotton,  especially 
with  respect  to  bleeding  on  washing.  Dye  two  skeins  of  cotton  yarn  in  a  bath  containing 
300  cc.  of  water,  20  per  cent  of  common  salt,  1  per  cent  of  soda  ash,  and  8  per  cent  of 


EXPERIMENTAL  STUDIES  289 

Diamine  Jet  Black;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  tem- 
perature for  one-half  hour;  wash  well,  and  pass  one  skein  into  a  bath  containing  300  cc. 
of  water  and  5  cc.  of  formaldehyde  solution  (40  per  cent  strength);  enter  at  120°  F., 
gradually  raise  to  165°  F.,  and  keep  at  that  temperature  for  one-half  hour;  then  wash 
well  and  dry.  Compare  the  colors  obtained  on  the  two  skeins  to  see  if  the  treatment 
affects  the  shade  in  any  manner;  then  make  tests  on  both  skeins  for  their  fastness  to 
washing. 

Exp.  107.  Dyeing  in  a  Cold  Bath.— Many  of  the  substantive  dyes  are  taken  up  by 
cotton  from  a  cold  bath  almost  as  well  as  from  a  hot  bath,  and  these  become  very  useful 
in  cases  where  it  is  not  desirable  to  employ  a  very  hot  liquor  in  the  dyebath.  Dye  five 
test  skeins  of  cotton  yarn  with  the  following  dyestuffs  respectively  in  baths  containing 
20  per  cent  of  common  salt  and  2  per  cent  of  the  dyestuff,  enter  cold  and  dye  (without 
heating)  for  three-quarters  of  an  hour;  then  wash  and  dry.  It  is  necessary  to  have  the 
yarn  very  well  boiled-out  for  this  method  of  dyeing,  as  otherwise  it  will  be  difficult  to 
obtain  good  penetration  of  the  coloring  matter  into  the  fiber.  It  is  also  well  to  add  to 
the  dyebath  a  small  amount  of  Turkey-red  oil  in  order  to  increase  the  penetration. 
Use  the  following  dyestuffs: 

Erika  BN  Chrysophenine 

Brilliant  Orange  G  Chicago  Blue  6B 

Heliotrope  2B 

For  the  dyeing  of  light  shades  soap  is  often  added  to  the  bath,  as  this  helps  the 
wetting-out  of  the  cotton;  for  heavy  shades,  besides  Turkey-red  oil,  there  may  also 
be  added  a  small  amount  of  soda  ash  to  give  a  better  exhaustion  of  the  bath. 

Exp.  108.  Dyemg  Substantive  Dyes  in  Connection  with  Logwood.— This  process 
is  mostly  used  for  the  production  of  fast  blacks  on  cotton,  the  Logwood  giving  depth  of 
color  and  fastness  to  washing,  while  the  substantive  dye  gives  tone  to  the  black  and 
usually  increases  the  fastness  of  the  color  to  acids.  Dye  a  test  skein  of  cotton  yarn  in  a 
bath  containing  300  cc.  of  water  10  per  cent  of  glaubersalt,  3  per  cent  of  Diamine  Jet 
Black  SS,  and  10  per  cent  of  Logwood  extract;  enter  at  140°  F.,  gradually  raise  to  the 
boil  and  dye  at  that  temperature  for  three-quarters  of  an  hour;  expose  to  the  air  for  several 
hours  in  order  to  oxidize  the  Logwood,  then  work  for  fifteen  minutes  in  a  cold  bath  of 
pyrolignite  of  iron  at  2°  Tw.,  containing  a  small  amount  of  chalk  to  neutralize  the  bath. 
This  latter  bath  is  for  the  purpose  of  combining  with  and  fixing  the  Logwood  dye.  Finally 
wash  well,  squeeze,  and  dry.  Test  the  color  so  obtained  for  its  fastness  to  washing  and 
acids. 

Exp.  109.  Shading  Substantive  Dyes  with  Basic  Dyes.— Substantive  dyes  act  as 
mordants  toward  basic  dyes,  on  which  account  the  latter  may  be  employed  for  purposes 
of  toppmg^or  shading  the  former.  According  to  the  depth  of  the  substantive  dveing, 
from  i  to  i  per  cent  of  basic  dye  may  be  fixed  with  considerable  fastness  to  washing. 
Almost  any  substantive  dye  may  be  used  as  the  bottom  color,  and  almost  any  basic  dye 
may  be  employed  for  topping.  The  dyeing  with  the  substantive  color  is  carried  out  in 
the  usual  manner,  while  the  topping  with  the  basic  color  is  done  in  a  fresh  cold  bath, 
either  with  or  without  the  addition  of  a  small  amount  of  acetic  acid.  The  method  is 
used  for  the  purpose  of  giving  increased  depth  of  color  as  well  as  increased  brightness: 
for  the  substantive  colors,  as  a  rule,  are  neither  very  intense  nor  verv  bright.  In  some 
cases  the  fastness  of  the  color  to  washing  and  light  is  also  increased.  Dye  five  test 
skeins  of  cotton  yarn  in  the  usual  manner  with  2  per  cent  of  Chrysophenine;  wash  well 
and  top  the  five  skeins  as  follows  in  cold  baths  containing  i  per  cent  of  the  respective 
dyestuffs: 

Methylene  Blue  "  Rhodamine 

Methyl  Violet  Auramine  O 

Malachite  Green 


290  APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 

Enter  cold  and  dye  at  that  temperature  for  one-half  hour;    wash  well    and  dry. 

Dye  a  skein  of  cotton  yarn  in  the  usual  manner  with  2  per  cent  of  Chicago  Blue  6B; 
wash  well  and  top  as  in  the  foregoing  test  with  j  per  cent  of  Methylene  Blue;  wash 
well  and  dry. 

Dye  a  skein  of  cotton  yarn  in  the  usual  manner  with  3  per  cent  of  Diamine  Scarlet  3B; 
wash  well  and  top  as  before  with  i  per  cent  of  Rhodamine. 

In  each  case  preserve  a  sample  of  the  skein  dyed  with  the  substantive  color  alone  and 
compare  it  with  the  topped  sample. 

Exp.  110.  Topping  of  Substantive  Dyes  on  Cutch. — This  method  is  often  employed 
for  the  production  of  heavy  browns,  as  the  bottom  color  of  the  Cutch  deepens  the  final 
color  of  the  substantive  dye  very  materially.  Cutch  is  the  extract  obtained  from  the 
acacia  plant,  and  is  a  tannin  material  containing  a  large  amount  of  natural  brown  color- 
ing matter.  Dye  two  skeins  of  cotton  yarn  in  a  bath  containing  300  cc.  of  water,  30 
per  cent  of  Cutch,  and  5  per  cent  of  bluestone;  enter  at  1G0°  F.,  gradually  raise  to  the 
boil  and  dye  at  that  temperature  for  one-half  hour;  squeeze,  and  pass  into  a  bath  con- 
taining 300  cc.  of  water  and  3  per  cent  of  chrome,  and  boil  for  fifteen  minutes;  wash 
well,  and  dye  one  of  the  skeins  in  a  fresh  bath  containing  300  cc.  of  water,  2  per  cent  of 
Diamine  Brown  M,  20  per  cent  of  common  salt,  and  3  per  cent  of  soap;  enter  at  140°  F., 
gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour,  then  wash 
well  and  dry.  The  addition  of  the  soap  to  the  last  bath  serves  to  soften  the  cotton  which 
becomes  rather  harsh  on  dyeing  with  Cutch.  Compare  the  colors  on  the  two  skeins  and 
test  each  for  its  fastness  to  washing. 

Exp.  111.  After-treatment  of  Substantive  Dyes  with  Sumac  and  Iron  Salts. — 
This  process  is  sometimes  employed  on  dark  colors,  and  especially  on  blacks,  to  increase 
the  depth  of  the  color  and  also  its  fastness  to  washing.  Dye  two  skeins  of  cotton  yarn 
in  the  usual  manner  with  G  per  cent  of  Diamineral  Black  B;  rinse,  and  steep  one  of  the 
skeins  for  one  hour  at  140°  F.  in  a  bath  containing  300  cc.  of  water  and  10  per  cent  of 
sumac  extract;  squeeze,  and  work  for  fifteen  minutes  in  a  cold  bath  of  pyrolignite  of 
iron  at  3°  Tw. ;  finally  wash  well  and  dry.  Compare  the  character  of  the  colors  obtained 
on  the  two  .skeins,  and  test  the  fastness  of  each  to  washing. 

Exp.  112.  Topping  of  Substantive  Dyes  with  Aniline  Black. — This  method  is  used 
for  the  production  of  fast  black  shades  on  cotton  with  the  substantive  dyes,  and  it  is 
said  at  a  lower  cost  than  when  Aniline  Black  alone  is  used.  The  aniline  salt  is  usually 
added  to  the  after-treatment  bath  of  chrome.  Dye  a  skein  of  cotton  yarn  in  the  usual 
manner  with  3  per  cent  of  Columbia  Black  FB;  squeeze  and  treat  in  the  following  bath: 
300  cc.  of  water,  1  gram  of  aniline  salt,  2\  cc.  of  concentrated  hydrochloric  acid,  and  l^ 
grams  of  chrome.  Work  in  this  solution  cold  for  one-half  hour,  then  slowly  raise  to  the 
boil,  and  continue  at  that  temperature  for  five  minutes;  then  wash  well  and  soap  off  in 
a  lukewarm  weak  soap  bath,  and  dry.  Test  the  black  obtained  in  this  manner  for 
fastness  to  light  and  washing. 

Exp.  113.  After-treatment  of  Substantive  Dyes  with  Pyrolignite  of  Iron. — Salts  of 
iron  appear  to  act  toward  substantive  dyes  much  in  the  same  manner  as  other  metallic 
salts,  though  the  fastness  to  water  is  probalsly  not  increased  to  the  same  degree.  Dye 
two  skeins  of  cotton  yarn  in  the  usual  manner  with  2  per  cent  of  Diamine  Catechine  B; 
wash  and  work  one  of  the  skeins  in  a  bath  containing  200  cc.  of  water  and  10  cc.  of  pyro- 
lignite of  iron  of  32°  Tw.  at  a  temperature  of  140°  F.  for  fifteen  minutes;  then  wash  well 
and  dry.  Compare  the  two  skeins  for  color  and  test  them  for  fastness  to  water  and 
washing. 

7.  List  of  the  Principal  Substantive  Dyes. — The  substantive  dyes 
form  a  very  large  and  ever-increasing  group.  Although  the  most  of  them 
are  applied  almost  exclusively  to  cotton,  nevertheless  many  of  them  are 


PRINCIPAL  SUBSTANTIVE   DYES 


291 


also  used  for  dyeing  wool  and  silk.  Some  of  the  substantive  dyes  are  also 
adapted  for  after-treatment  with  bluestone  and  chrome.  These  are  indi- 
cated in  a  separate  list. 


Acetopurpurine  8B 

Alkali  Bordeaux 

Alkali  Claret 

Alkali  Grenat 

Alkali  Pink 

Alkali  Purple 

Alkali  Purpurine 

Alkali  Red 

Azidine  Bordeaux 

Azidine  Brilliant  Red 

Azidine  Corinth 

Azidine  Fast  Red 

Azidine  Fast  Scarlet 

Azidine  Purpurine 

Azidine  Red 

Azidine  Scarlet 

Azo  Purpurine 

Benzamine  Fast  Red 

Benzamine  Maroon 

Benzo  Bordeaux 

Benzo  Fast  Red  L  and  GL 

Benzo  Fast  Rose 

Benzo  Fast  Rubine 

Benzo  Fast  Scarlet 

Benzo  New  Red 

Benzo  Nitrol  Bordeaux 

Benzopuripurine  B,  4B,  6B, 

and  lOB 
Benzo  Red  lOB  and  SG 
Benzo  Rhoduline  Red  B  and 

3B 
Benzo  Rubine 
Benzo  Scarlet 
Blackley  Scarlet 
Bordeaux  COV 
Brilliant  Congo 
Brilliant  Dianil  Red 
Brilliant  Geranine 
Brilliant  Purpurine  4B  and 

lOB 
Buffalo  Direct  Cardinal 
Buffalo  Direct  Crimson 
Buffalo.  Direct  Garnet 
Buffalo  Direct  Pink 
Buffalo  Direct  Red  4B 
Chicago  Red 


(a)  Red 

Chloramine  Red 
Chlorantine  Pink 
Chlorantine  Red  4B  and  8B 
Chlorazol  Fast  Red 
Chlorazol  Red 
Columbia  Bordeaux 
Columbia  Fast  Scarlet 
Columbia  Red  4B  and  SB 
Congo  Corinth  G 
Congo  Magenta 
Congo  Red 
Congo  Rubine 
Cosmos  Red 
Cotton  Corinth 
Cotton  Fast  Red 
Cotton  Red  4B 
Cotton  Rubine 
Crumpsall  Direct  Fast  Red 
Delta  Direct  Red  5B 
Deltapurpurine  5B,  7B,  G 
Diamine  Azo  Bordeaux 
Diamine  Azo  Scarlet 
Diamine  Bordeaux  B  and  S 
Diamine  Brilliant  Bordeaux 
Diamine  Brilliant  Rubine 
Diamine  Brilliant  Scarlet  S 
Diamine  Cotton  Red 
Diamine  Fast  Red  F 
Diamine  Fast  Scarlet 
Diamine  Nitrazol  Bordeaux 
Diamine  Nitrazol  Scarlet 
Diamine  Purpurines 
Diamine  Reds 
Diamine  Rose  BD,  BG  and 

GD 
Diamine  Rubine 
Diamine  Scarlet  B,  3B  and 

HS 
Diamine  Violet  Red 
Dianil  Bordeaux 
Dianil  Fast  Red 
Dianil  Fast  Scarlet 
Dianil  Garnet 
Dianil  Pink 

Dianil  Ponceau  G  and  2R 
Dianil  Reds 


Dianol  Brilliant  Reds 
Dianol  Fast  Bordeaux 
Dianol  Fast  Clarets 
Dianol  Fast  Pink 
Dianol  Fast  Reds 
Dianol  Fast  Scarlets 
Dianol  Scarlets 
Diazo  Bordeaux  7B 
Diazo  Brilliant  Scarlets 
Diazo  Fast  Bordeaux  BL 
Diazo  Fast  Red  7BL 
Diazo  Geranine  B 
Diazo  Rubine 
Diazogen  Bordeaux 
Diazogen  Corinth 
Diazogen  Reds 
Diazogen  Scarlet 
Diphenyl  Blue  Red 
Diphenyl  Fast  Bordeaux 
Diphenyl  Fast  Red 
Diphenyl  Purpurine 
Diphenyl  Red  SB 
Direct  Acid  Reds 
Direct  Bordeaux 
Direct  Brilliant  Bordeaux 
Direct  Brilliant  Red  lOB 
Direct  Fast  Acid  Reds 
Direct  Pink 
Direct  Reds 
Direct  Safranine 
Direct  Scarlet 
Erie  Cardinal 
Erie  Congo 
Erie  Delta  Red 
Erie  Fast  Red  FD 
Erie  Garnet 
Erie  Pink 
Erie  Red  4B 
Erika 

Fast  Cotton  Reds 
Fast  Red  8BL 
Formal  Red 
Geranine  G  and  2B 
Hessian  Bordeaux 
Hessian  Brilliant  Purple 
Hessian  Fast  Red 


292 


APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 


Hessian  Fast  Rubine 
Hessian  Purple  B,  D,  and  N 
Naphthamine  Bordeaux 
Naphthamine  Fast  Scarlet 
Naphthamine  Reds 
Naphthamine  Scarlets 
Niagara  Fast  Reds 
Niagara  Fast  Scarlets 
Oxamine  Bordeaux 
Oxamine  Clarets 
Oxamine  Fast  Claret 
Oxamine  Fast  Red 
Oxamine  Garnet 
Oxamine  Maroon 
Oxamine  Reds 
Para  Garnet  G 


Alkali  Orange 
Azidine  Orange 
Benzo  Fast  Orange  S 
Benzo  Orange  R 
Brilliant  Orange  G 
Buffalo  Direct  Orange 
Chicago  Orange 
Chloramine  Orange 
Chlorantine  Orange 
Chlorophenine  Orange 
Columbia  Orange 
Congo  Orange  G  and  R 
Cotton  Orange  G  and  R 
Diamine  Fast  Orange 
Diamine  Nitrazol  Orange 
Diamine  Orange 


Alkali  Fast  Yellow 
Alkali  Leather  Yellow 
Alkali  Yellow  R 
Aurophcnine 
Azidine  Fast  Yellow 
Azidine  Yellows 
Benzamine  Fast  Yellow 
Benzo  Fast  Yellow 
Boston  Direct  Yellow 
Brilliant  Yellow 
Buffalo  Direct  Yellow 
Carbazole  Yellow 
Chloramine  Yellow  GG  and 

M 
Chlorantine  Yellow  T 
Chlorazol  Fast  Yellow 


Para  Scarlet  G 
Paranil  Bordeaux 
Purpuramine 
Renol  Bordeaux 
Renol  Brilliant  Red 
Renol  Corinth 
Renol  Fast  Scarlet 
Renol  Orange  R 
Renol  Pinks 
Renol  Rosamine 
Renol  Rubine 
Renolamine  Red 
Rosanthrene 
Rosanthrene  Bordeau  a 
Rosazurines 
Rosophenine 

(b)  Orange 
Dianil  Orange 
Diazo  Brilliant  Orange 
Diazogen  Orange 
Diphenyl  Oranges 
Direct  Brilliant  Orange 
Direct  Orange 
Erie  Orange 
Formal  Orange 
Hessian  Orange 
Mikado  Orange 
Naphthamine  Orange 
New  Toluylene  Orange 
Niagara  Fast  Orange 
Orange  TA 
Osfamine  Orange 

(c)  Yellow 
Chlorophenine 
Chromine  G 
Chrysamine  G  and  R 
Chrysobarine 
Chrysophenine 
Clayton  Yellow 
Columbia  Yellow 
Cotton  Yellow  G  and  R 
Curcumine  S 
Diamine  Fast  Yellow 
Diamine  Gold 
Diamine  Yellow 
Dianil  Yellow 
Dianol  Fast  Yellow 
Dianol  Yellow  Y 
Diphenyl  Chlorine  Yellow 


Rosophenine  Pink 
St.  Denis  Red 
Salmon  Red 
Scarlet  for  Cotton 
Sultan 

Sultan  Scarlet 
Thiazine  Reds 
Titan  Pink 
Toluylene  Bordeaux 
Toluylene  Red 
Triazol  Bordeaux 
Triazol  Corinth 
Triazol  Fast  Red 
Triazol  Red  lOB 
Trona  Red 


Oxydiamine  Orange 
Para  Orange 
Paramine  Direct  Orange 
Pluto  Orange  G 
Polyphenyl  Orange 
Pyramine  Orange  R  and  3G 
Pyrazol  Orange 
Renol  Orange 
Rosanthrene  Orange 
Stilbene  Orange 
Sultan  Orange 
Titan  Orange 
Toluylene  Fast  Orange 
Toluylene  Orange 
Vesuvine  Orange 


Diphenyl  Chrj'soin 
Diphenyl  Citronine 
Diphenyl  Fast  Yellow 
Diphenyl  Phosphine 
Diphenyl  Yellow 
Direct  Fast  Yellow 
Direct  Yellows 
Erie  Fast  Yellow 
Erie  Yellow 
Fast  Yellow  R 
Formal  Yellow 
Hessian  Yellow 
Kresotine  Yellow 
Mekong  Yellow 
Mikado  Gold  Yellow 
Mikado  Yellow 


PRINCIPAL  SUBSTANTIVE   DYES 


293 


Mimosa 

Naphthamine  Yellow 

Nitrophenine 

Oriol 

Oxydiamine  Yellow 

Oxy  Dianil  Yellow 

Oxyphenine 

Para  Yellow 

Paramiiie  Direct  Yellow 

Paranil  Yellow 


Alkali  Green 
Azidine  Dark  Green 
Azidine  Green 
Benzo  Dark  Greens 
Benzo  Greens 
Benzo  Olive 
Brilliant  Benzo  Green 
Chloramine  Green 
Chlorazol  Green 
Columbia  Dark  Green 
Columbia  Green 
Diamine  Dark  Green 
Diamine  Green 
Diamine  Nitrazol  Green 
Dianil  Dark  Green 
Dianil  Greens 
Dianol  Chrome  Green 


Acetylene  Blue 

Acetylene  Sky  Blue 

Alkali  Azo  Blue 

Alkali  Azurine 

Alkali  Brilliant  Blue 

Alkali  Chrome  Blue 

Azidine  Black  Blue 

Azidine  Blues 

Azidine  Sky  Blue 

Azo  Blue 

Azo  Corinth 

Azo  Dark  Blue 

Azo  Mauve 

Azo  Navy  Blue  B 

Benzamine  Blues 

Benzamine  Para  Blue 

Benzo  Azurine  G,  3G  and  R 

Benzo  Blue 

Benzo  Chrome  Dark  Blue  B 

and  N 
Benzo  Copper  Blue  B 


Paraphenine  Yellow 

Phenine  Yellow 

Polyphenyl  Yellow 

Primuline 

Pyramine  Yellow 

Renol  Yellow 

Salicine  Yellow  G  and  GG 

Stilbene  Yellow 

Sultan  Yellow 

Sun  Yellow 

(d)  Green 
Dianol  Dark  Green 
Dianol  Fast  Green 
Dianol  Green 
Dianol  Olive 
Dianol  Pea  Green 
Diazo  Olive 
Diphenyl  Green 
Direct  Brilliant  Green 
Direct  Dark  Green 
Direct  Green 
Eboli  Green 
Erie  Direct  Green 
Erie  Green 
Formal  Olive 

Naphthamine  Dark  Green 
Naphthamine  Green 

(e)  Blue 
Benzo  Cyanide  B,  3B  and  R 
Benzo  Dark  Blue  R,  G,  and 

5G 
Benzo  Fast  Blue 
Benzo  Indigo  Blue 
Benzo  Marine  Blue 
Benzo  Navy  Blue 
Benzo  New  Blue 
Benzo  Pure  Blue 
Benzo  Red  Blue  G 
Benzo  Sky  Blue 
Benzo  Steel  Blue 
Betamine  Blue  SB 
Brilliant  Azurine 
Brilliant  Benzo  Blue  6B 
Brilliant  Congo  Blue 
Brilliant  Fast  Blues 
Brilliant  Sky  Blue 
Buffalo  Direct  Blue 
Chicago  Blues 
Chloramine  Blue 


Thiazol  Yellow  G  and  R 

Thiochromogene 

Thioflavine  S 

Titan  Yellow 

Toluylene  Yellow 

Triazol  Fast  Yellow 

Triazol  Yellow 

Turmerine 

Xanthine 

Yellow  CR  and  D 


Osfamine  Dark  Green 
Osfanil  Dark  Green 
Oxamine  Dark  Green 
Oxamine  Green 
Para  Fast  Green 
Para  Green 
Para  Olive 
Paramine  Green 
Polyphenyl  Green 
Renol  Dark  Green 
Renol  Green 
Renol  Olive 
Renolazine  Green 
Tolamine  Green 
Triazol  Green 
Union  Green 


Chloramine  Sky  Blue 
Chlorantine  Pure  Blue 
Chlorazol  Blue 
Chlorazol  Brilliant  Blue 
Chlorazol  Dark  Blue 
Chlorazol  Dark  Navy 
Chlorazol  Fast  Blue 
Chlorazol  Sky  Blue 
Columbia  Blue 
Columbia  Dark  Blue 
Columbia  Fast  Blue 
Congo  Blue 
Congo  Fast  Blue 
Congo  Pure  Blue 
Congo  Sky  Blue 
Cotton  Blue 
Cotton  Pure  Blue 
Diamine  Azo  Blue  R  and  2R 
Diamine  Bengal  Blue 
Diamine  Blue  BX,  RW,  BG, 
2B,  3B 


294 


APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 


Diamine  Brilliant  Blue  C! 
Diamine  Cyaninc 
Diamine  Dark  Blue 
Diamine  Fast  Blue 
Diamine  Fast  Brilliant  Blue 
Diamine  New  Blue 
Diamine  Pure  Blue 
Diamine  Sky  Blue 
Diamine  Steel  Blue 
Diamineral  Blue 
Diaminogene  Blue 
Diaminogene  Dark  Blue 
Diaminogene  Sky  Blue 
Dianil  Azurine 
Dianil  Blues 
Dianil  Dark  Blue 
Dianil  Indigo 
Diar.ol  Blues 
Dianol  Brilliant  Blue 
Dianol  Dark  Blue 
Dianol  Fast  Blue 
Dianol  Sky  Blue 
Dianol  Steel  Blue 
Diazo  Blue 
Diazo  Indigo  Blue 
Diazo  Navy  Blue 
Diazo  Red  Blue 
Diazo  Sky  Blue 
Diphenyl  Blue  3G 
Dijihenyl  Brilliant  Blue 
Diphenyl  Fast  Blue 
Direct  Blue  2BX,  and  3BX 
Direct  Blue  B  and  R 


Alkali  Azo  Violet 
Azidine  Violet 
Azo  Corinth 
Azo  Gallein 
Azo  Mauve 
Azo  Violet 
Benzamine  Violet 
Benzo  Fast  Heliotrope 
Benzo  Fast  Violet 
Benzo  Violet 
Bordeaux  COV 
Bordeaux  extra 
Brilliant  Benzo  Violet 
Brilliant  Congo  Violet 
Chloramine  Violet 
Chlorantine  Lilac 
Chlorazol  Violet 


Direct  Dark  Blue 

Direct  Fast  Blue 

Direct  Indigo  Blue 

Direct  Indone  Blue 

Direct  Sky  Blue 

Eboli  Blue  B,  6B,  and  2R 

Eholi  Dark  Blue 

Eboli  Sky  Blue 

Erie  Blue  BX  and  2G 

Formal  Blue 

Indigene  Blue 

Isamine  Blue 

Melogene  Blue 

Naphthamine  Blue 

Naphthamine  Brilliant  Blue 

Naphthamine  Deep  Blue 

Naphthamine  Indigo 

Naphthamine  Sky  Blue 

Naphthazurine 

Naphthogene  Blues 

Naphthyl  Blue  BB 

New  Toluylene  Blue 

Niagara  Blues 

Niagara  Fast  Blue 

Niagara  Sky  Blue 

Opaline 

Osfamine  Blues 

Osfanil  Blues 

Osfanil  Pure  Blue 

Oxamine  Blue 

Oxamine  Copper  Blue 

Oxamine  Dark  Blue 

Oxamine  Pure  Blue 

(f)  Violet 
Clemantine 
Columbia  Violet 
Congo  Corinth 
Congo  Violet 
Diamine  Brilliant  Violet 
Diamine  Fast  Violet 
Diamine   Heliotrope   G,   O, 

and  B 
Diamine  Violet  N 
Dianil  Bordeaux 
Dianil  Violet 
Dianol  Brilliant  Violet 
Dianol  Violets 
Diazo  Fast  Violets 
Diazogen  Violet 
Diphenyl  Fast  Violet 
Diphenyl  Violet 


Oxy  Chlorazol  Blue 
Oxydiamine    Blue    R,    3R, 

and  G 
Oxy  phenol  Sky  Blue 
Para  Blues 
Paramine  Blues 
Paramine  Navy  Blue 
Paramine  Sky  Blue 
Phenamine  Blue 
Renol  Blues 
Renol  Fast  Blue 
Renol  Indigo  Blue 
Renol  Light  Blue 
Renol  Pure  Blue 
St.  Denis  Blue 
Solamine  Blues 
Titan  Como 
Titan  Dark  Navy 
Titan  Fast  Navy 
Titan  Navy 
Toledo  Blue  V 
Toluylene  Blue 
Toluylene  Dark  Blue 
Triamine  Blue 
Triazol  Blue 
Triazol  Dark  Blue 
Triazol  Indigo  Blue 
Triazol  Pure  Blue 
Trisulfone  Blue 
Union  Navy  Blue 
Zambesi  Indigo 
Zambesi  Pure  Blue 


Direct  Violet 

Erie  Violet 

Heliotrope 

Hessian  Bordeaux 

Hessian  Violet 

Naphthamine  Violets 

Osfamine  Violets 

Osfanil  Violet 

Oxamine  Violet 

Oxydiamine    Violet     B.     R, 

and  G 
Paramine  Violet 
Renol  Violet 
Rosanthrene  Violet 
St.  Denis  Violet 
Triazol  Violet 
Trisulphone  Violet 


PRINCIPAL  SUBSTANTIVE   DYES 


295 


Alkali  Bronze 
Alkali  Brown 
Alkali  Chrome  Brown 
Alkali  Ciitch 
Alkali  Dark  Brown 
Alkali  Mode  Brown 
Alkali  New  Brown 
Alkali  Red  Brown 
Azidine  Bronze 
Azidine  Browns 
Azidine  Dark  Browns 
Benzamine  Browns 
Benzamine  Dark  Brown 
Benzo  Bronze 
Benzo  Brown 
Benzo  Chrome  Brown 
Benzo  Dark  Brown 
Benzo  Nitrol  Browns 
Catechu  Brown 
Chicago  Brown 
Chloramine  Browns 
Chlorantine  Brown, 
Chlorazol  Browns 
Chlorazol  Catechine 
Chlorazol  Deep  Browns 
Chromanil  Brown 
Columbia  Browns 
Congo  Browns 
Copper  Brown 
Cotton  Browns 
Cotton  Dark  Browns 
Crumpsall   Direct   Fast 

Browns 
Crumpsall  Direct  Fast 

Khaki 


(g)  Brown 
Cupranil  Browns 
Diamine  Bronze 
Diamine  Browns 
Diamine  Catechines 
Diamine  Cutch 
Diamine  Fast  Browns 
Diamine  Nitrazol  Browns 
Diamineral  Browns 
Dianil  Browns 
Dianil  Chrome  Brown 
Dianil  Fast  Brown 
Dianil  Japonine 
Dianol  Bronze 
Dianol  Browns 
Dianol  Catechine 
Dianol  Cotton  Brown 
Dianol  Union  Browns 
Diazo  Browns 
Diazogen  Brown 
Diphenyl  Bronze 
Di  phenyl  Browns 
Diphenyl  Catechine 
Diphenyl  Fast  Brown 
Diphenyl  Red  Brown 
Direct  Bronze  Brown 
Direct  Browns 
Direct  Dark  Brown 
Direct  Fast  Brown 
Direct  Naphthamine  Browns 
Discharge  Browns 
Erie  Browns 
Erie  Fast  Brown 
Fast  Cotton  Brown 
Formal  Brown 
Havana  Brown 


Hessian  Brown 
Mikado  Browns 
Naphthamine  Bronze 
Naphthamine  Browns 
New  Toluylene  Browns 
Nitramine  Brown 
Nitranil  Browns 
Oxamine  Browns 
Oxamine  Dark  Brown 
Oxamine  Maroon 
Oxydiamine  Browns 
Oxyphcnol  Browns 
Panama  Brown 
Para  Bronze 
Para  Brown 
Paraminc  Brown 
Paramine  Dark  Brown 
Paranil  Browns 
Pegu  Browns 
Pluto  Browns 
Renol  Bronze 
Renol  Browns 
Renol  Dark  Brown 
Renol  Deep  Browns 
Renol  Havana 
Renol  Khaki 
Renol  Maroon 
Terra  Cotta 
Thiazine  Browns 
Toluylene  Browns 
Triazol  Browns 
Trisulphone  Bronze 
Trisulphone  Browns 
Union  Brown 
Zambesi  Browns 


Alkali  Black  B  and  G 
Alkali  Blue  Black 
Alkali  Chrome  Black 
Alkali  Deep  Black 
Azidine  Blacks 
Azidine  Carbon 
Azidine  Direct  Blacks 
Benzo  Chrome  Black 
Benzo  Chrome  Blue  Black 
Benzo  Fast  Blacks 
Benzo  Nitrol  Black 
Carbide  Blacks 
Chloramine  Blacks 


(h)  Black 
Chlorazol  Fast  Blacks 
Chromanil  Blacks 
Cold  Black 
Columbia  Blacks 
Columbia  Fast  Blacks 
Cotton  Blacks 
Cotton  Milling  Black 
Diamine  Azo  Black 
Diamine  Beta  Black 
Diamine  Blacks 
Diamine  Blue  Black 
Diamine  Deep  Black 
Diamine  Fast  Blacks 


Diamine  Jet  Black 
Diamine  Milling  Blacks 
Diamine  Nitrazol  Black 
Diamineral  Blacks 
Diaminogene  B,  and  extra 
Dianil  Blacks 
Dianol  Blacks 
Dianol  Brilliant  Blacks 
Dianol  Chrome  Blue  Black 
Dianol  Copper  Black 
Dianol  Diazo  Blacks 
Dianol  Fast  Blacks 
Dianol  Jet  Black 


296 


APPLICATION  OF  SUBSTANTIVE  DYES  TO  COTTON 


Dianol  Union  Black 
Diazine  Black 
Diazo  Blacks 
Diazo  Blue  Black 
Diazo  Brilliant  Black 
Diazo  Fast  Blacks 
Diazogen  Black 
Diphenyl  Blacks 
Diphenyl  Blue  Black 
Diphenyl  Fast  Black 
Direct  Blacks 
Direct  Blue  Blacks 
Direct  Chrome  Black 
Direct  Deep  Black 
Direct  Xaphthamine  Black 
Erie  Blacks 
Formal  Blacks 
Grounding  Black  for  Cotton 


Benzo  Fast  Gray 
Chicago  Gray 
Diamine  Fast  Gray 
Diamine  Gray 
Dianol  Gray 


Hessian  Fast  Black 
Indigene  Blacks 
Ingrain  Blacks 
Isodiphenyl  Black 
Melantherine 
Naphthamine  Blacks 
Naphthamine  Deep  Black 
Naphthamine  Direct  Blacks 
Xaphthamine  Fast  Blacks 
Neropaline 
Niagara  Fast  Black 
N3'anza  Black 
Osfamine  Black 
Osfanil  Blacks 
Oxamine  Blacks 
Oxydiamine  Blacks 
Oxjdiamine  Carbon 
Oxydiaminogenes 

(i)  Gray 

Diphenyl  Fast  Gray 
Diphenyl  Gray 
Direct  Gray 
Fast  Grav 


Panama  Black 
Para  Diamine  Blacks 
Paramine  Blacks 
Paranil  Black 
Patent  Dianil  Blacks 
Pluto  Blacks 
Polyphenyl  Black 
Renol  Blacks 
Renol  Deep  Black 
Renolamine  Blacks 
Tabora  Black 
Titan  Blacks 
Titan  Fast  Blacks 
Toluylene  Black 
Triazol  Blacks 
Violet  Black 
Zambesi  Blacks 


Hessian  Copper  Gray 
Hessian  Gray 
Neutral  Gray 
Zambesi  Gray 


8.  Substantive  Dyes  Suitable  for  After-treatment  with  Bluestone 


Azo  \'iolet 

Benzo  Azurine  G,  3G,  and 
Benzo  Blue 
Benzo  Copper  Blue  B 
Benzo  Cj-anine  B,  3B,  and 
Benzo  Indigo  Blue 
Benzo  Pure  Blue 
Benzo  Skj'  Blue 
Brilliant  Azurine 
Brilliant  Benzo  Blue  6B 
Catechu  Brown 
Chicago  Blue  6B,  B,  RW 
Chloramine  \'iolet  R 
Chrj'samine  G  and  R 
Congo  Blue  2B 
Congo  Brown 
Cotton  Yellow  R,  G 


Cresotine  Yellow 
R  Diamine  Bengal  Blue 

Diamine  Blue  RW 

Diamine  Brilliant  Blue  G 
R  Diamine  Brown  M,  B,  G3 

Diamine  Catechine 

Diamine  Fast  Black  F 

Diamine  New  Blue 

Diamine  Orange  B 

Diamine  Sky  Blue  FF 

Diamineral  Black 

Diamineral  Blue 

Diamineral  Brown 

Dianil  Blacks 

Dianil  Blues 

Dianil  Brown 

Dianil  Copper  Brown 


Dianil  Dark  Blue 
Dianil  Fast  Brown 
Dianil  Japonine 
Dianil  Orange 
Dianil  Yellows 
Diazo  Blue 
Diazo  Indigo  Blue 
Diazo  Navy  Blue 
Hessian  Copper  Gray 
Oxamine  Blue 
Oxamine  Red 
Oxamine  Violet 
Oxydiamine  Blue 
Oxydiamine  Orange 
Phenamine  Blue 
Pluto  Orange  G 
Zambesi  Black 


9.  Substantive  Dyes  Suitable  for  After-treatment  with  Chrome  and  Bluestone 
Benzo     Chrome     Black     B  Benzo  Green  Chromanil  Brown 


and  N  Benzo  Indigo  Blue 

Benzo  Chrome  Blue  Black  B  Carbide  Black  BO 
Benzo  Chrome  Brown  Catechu  Brown 

Benzo  Dark  Green  Chromanil  Black 


Chrysamine  G  and  R 
Columbia  Black  Blue  G 
Columbia  Chrome  Black 
Congo  Brown  G,  R 


PRINCIPAL  SUBSTANTIVE   DYES 


297 


Cotton  Yellow  R 
Cresotine  Yellow 
Cupranil  Brown 
Diamine  Browns 
Diamine  Catechine 
Diamine  Dark  Blue  B 
Diamine  Fast  Black 
Diamine  Jet  Blacks 
Diamineral  Black 


Dianil  Blacks 

Dianil  Yellow  3G 

Dianil  Blues 
Dianil  Brown 
Dianil  Copper  Brown 
Dianil  Dark  Blue 

Direct  Deep  Black  ERW 
Oxamine  Blue  BG 
Oxamine  Violet 
Pluto  Blacks 

Dianil  Fast  Brown 
Dianil  Green 
Dianil  Japonine 
Dianil  Orange  N 

Pluto  Orange  G 
Toluylene  Orange  G 
Trisulphone  Brown  S 
Zambesi  Black 

CHAPTER  XIV 
SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

1.  The  Substantive  Colors  on  Wool. — These  dyes  have  gained  con- 
siderable favor  in  various  branches  of  wool  dyeing,  especially  for  knit- 
ting yarns  fast  to  washing,  carded  avooI  and  worsted  yarns  fast  to  milling, 
shoddy  yarns,  loose  wool,  and  also  for  the  dyeing  of  slubbing  and  yarns  in 
machines.*  For  the  latter  they  are  especially  adapted  owing  to  their 
great  solubility  in  water.  The  chief  recommendation  of  these  dyes  to 
wool  is  their  good  fastness  to  washing,  and  in  many  cases  excellent  fast- 
ness to  milling,  t  This  is  especially  true  of  the  after-treated  dyeings. 
Most  of  the  substantive  colors  are  also  fast  to  stoving.  The  fastness  of 
the  substantive  colors  to  washing  is,  as  a  rule,  much  better  on  wool  than 
it  is  on  cotton.  The  same  is  also  true  regarding  the  fastness  to  light. 
The  exhaustion  of  the  bath  is  also  generally  better  when  wool  is  dyed. 

The  general  method  of  dyeing  the  substantive  dyes  on  wool  is  to  prepare 
the  bath  with  10  to  20  per  cent  of  glaubersalt  and  5  per  cent  of  ammo- 
nium acetate;  enter  the  goods  at  140°  F.  and  slowly  bring  to  the  boil,  and 
dye  at  that  temperature  for  three-quarters  of  an  hour.  In  case  the  bath 
is  not  thoroughly  exhausted  add  about  2  per  cent  of  acetic  acid  and  con- 

*  The  substantive  dyes  have  not  heretofore  been  used  for  the  dyeing  of  woolen 
goods  to  the  extent  that  would  be  expected  considering  their  good  quahtics  for  this 
purpose.  There  has  prolsably  been  more  or  less  lack  of  information  bj^  most  dyers 
concerning  their  use  on  wool,  as  the  emphasis  has  always  been  laid  on  their  particular 
use  for  cotton,  so  that  most  people  think  of  them  exclusively  as  cotton  dyes.  One 
reason  for  their  not  being  adopted  as  wool  dyes  has  been  the  fact  that  as  a  group  they 
have  been  considerably  more  costly  than  the  acid  dyes  or  even  the  chrome  dyeing 
colors,  a  condition  which  has  been  due  chiefly  to  the  fact  that  the  more  important 
of  these  dyes  have  been  under  patent  restrictions.  At  the  present  time  this  is  no 
longer  the  case,  as  many  of  the  very  desirable  substantive  dyes  arc  now  free  from 
patents.  In  many  cases  the  substantive  dyes  may  be  employed  for  wool  with  as  good 
success  in  the  production  of  fulling  fast  colors  as  the  chrome  and  alizarine  dyes,  and  since 
no  mordanting  operation  is  required  their  method  of  application  is  much  simpler  and 
cheaper. 

t  The  fastness  to  milling  of  many  of  the  substantive  dyes  on  wool  is  much  better 
than  that  of  most  of  the  acid  dyes.  The  colors,  however,  are  not  as  bright  and  pure  in 
tone  as  those  of  the  acid  dyes.  Frequently,  also  the  tone  of  the  color  on  wool  is  quite 
different  from  that  obtained  on  cotton  with  the  same  dye. 

298 


DYEING  SUBSTANTIVE  COLORS  ON  WOOL  299 

tinue  boiling  for  fifteen  minutes.  Sometimes,  however,  the  bath  is  pre- 
pared simply  with  the  glaubersalt  and  acetic  acid.*  The  idea  of  employ- 
ing ammonium  acetate  is  due  to  the  fact  that  these  dyes  are  liable  to 
exhaust  too  quickly  if  the  acid  is  added  to  start  with  and  thus  give  rise  to 
uneven  dyeings;  whereas  with  ammonium  acetate,  the  bath  becomes 
acid  only  slowly  at  a  boiling  temperature  by  the  decomposition  of  the 
ammonium  acetate  into  ammonia  (which  is  volatilized  from  the  bath)  and 
acetic  acid. 

It  should  be  observed  that  in  dyeing  wool  with  the  substantive  colors, 
neutral  baths,  or  such  as  are  but  slightly  acidulated  with  acetic  acid,  with 
few  exceptions,  are  the  most  serviceable.  If  the  baths  are  made  too 
strongly  acid,  the  color  is  taken  up  too  rapidly  by  the  wool,  and  uneven 
dyeings  may  result,  which  cannot  afterwards  be  improved,  even  by  pro- 
longed boiling.  In  the  case  of  material  which  is  difficult  to  dye  level,  or 
if  compound  shades  are  not  readily  obtained,  it  is  best  to  begin  the  dyeing 
without  the  addition  of  acid,  and  only  when  the  greater  part  of  the  color 
has  been  taken  up  should  the  acid  be  added  to  the  bath  in  order  to  increase 
the  exhaustion.  It  should  also  be  borne  in  mind  that  any  vegetable 
matter  present  in  the  wool  is  not  dyed  as  much  in  an  acid  bath  as  in  a  neu- 
tral one. 

^ome  of  the  substantive  colors  on  wool  may  be  after-treated  with 
chromium  or  copper  salts  to  produce  faster  shades  much  in  the  same  man- 
ner as  was  described  in  the  case  of  cotton  dyeing. 

The  after-treatment  with  chrome  or  chromium  fluoride  is  usually  car- 
ried out  by  adding  the  salts  to  the  exhausted  dyebath  with  the  addition 
of  3  to  4  per  cent  of  acetic  acid  and  using  about  one-half  the  weight  of 
chrome  as  dyestuff  or  about  the  same  weight  of  chromium  fluoride  as  dye- 
stuff.  The  dyeings  may  also  be  after-treated  with  bluestone  in  the  same 
manner  as  with  chrome,  about  the  same  weight  of  bluestone  as  dyestuff 
being  taken.  An  after-treatment  with  both  chrome  and  bluestone  may 
be  simultaneously  effected  in  the  same  manner.     The  metallic  salt  should 

*  A  variation  of  the  process  which  is  apphcable  in  the  case  of  some  of  the  substan- 
tive dyes  is  to  replace  the  acetic  acid  and  glaubersalt  with  a  corresponding  amount  of 
sodium  bisulphate  (2  to  5  per  cent) . 

The  use  of  sulphuric  acid  in  place  of  acetic  acid  in  the  dyeing  of  substantive  colors 
on  wool  is  not  to  be  recommended,  as  the  use  of  this  acid  will  generally  cause  the  color 
to  go  on  the  fiber  too  rapidly,  thus  giving  rise  to  uneven  results.  In  the  case  of  some  of 
the  blue  substantive  dyes,  however,  where  the  color  is  hardly  taken  up  at  all  from  a 
neutral  bath,  it  is  well  to  first  add  about  2  per  cent  of  acetic  acid  to  the  bath,  and  then 
after  dyeing  for  some  time,  to  add  a  small  quantity  of  sulphuric  acid  (2  per  cent) . 

Some  of  the  substantive  dyes  may  be  dyed  on  wool  mordanted  with  chrome,  or  be 
dyed  first  and  chromed  afterwards  (like Diamine  Fast  Red,  Geranine,  and  Benzo  Orange). 
The  after-chroming  may  be  done  in  the  same  bath  as  the  dyeing,  using  either  chrome  or 
chromium   fluoride. 


300  SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

not  be  added  until  the  bath  is  quite  well  exhausted  of  the  dye.  In  order  to 
obtain  a  better  exhaustion  of  the  dyebath  for  after-treatment  it  is  best 
to  add  about  3  to  5  per  cent  of  acetic  acid  to  the  bath  in  finishing  the  dye- 
ing; in  case  the  bath  does  not  exhaust  well,  it  is  best  to  carry  out  the  after- 
treatment  in  a  separate  bath  with  the  addition  of  4  per  cent  of  acetic  acid. 
Substantive  dyes  on  wool  after-treated  with  bluestone  retain  their  remark- 
able fastness  to  light  even  after  fullmg,  provided  a  neutral  curd  soap  is 
used;  free  alkaU  (which  is  generally  present  in  soft  soap)  should  never  be 
present  in  the  soap  used  under  these  circumstances.* 

The  substantive  dyes  have  considerable  importance  in  that  branch 
of  woolen  dyeing  involving  fabrics  containing  a  mixture  of  wool  and 


Fig.  163. — Reel  Dyeing  ■Machine.     (James  Hunter  Machine  Co.) 

cotton  (union  goods  and  woolen  or  worsted  goods  containing  cotton  or 
mercerized  cotton  effect  threads).  Owing  to  the  fact  that  many  of  these 
dyes  may  be  dyed  on  both  fibers  simultaneously  in  one  bath  they  are  fre- 
quently spoken  of  in  this  connection  as  "  union  dyes."  Their  use  has 
simplified  the  dyeing  of  union  goods  to  a  very  great  extent.  A  full  dis- 
cussion of  their  use  in  this  particular  will  be  taken  up  in  the  section  on  the 
dyeing  of  union  fabrics. 

2.  The  Substantive  Colors  on  Silk. — The  majority  of  these  colors  may 
be  dyed  on  silk,  giving  shades  of  considerable  fastness  to  washing  and 

*  This  after-treatment  with  chrome  and  bluestone  has  the  effect  of  increasing  the 
fastness  of  the  colors  to  light  and  fulling.  There  are  only  certain  of  the  dyes  which 
have  their  fastness  thus  increased,  while  with  some  the  fastness  is  not  particularly 
affected.     The  after-treatment  also  has  the  effect  of  somewhat  dulling  the  shade. 


DYEING  SUBSTANTIVE  COLORS  ON  SILK  301 

water  *  as  well  as  to  light,  hence  they  are  of  considerable  importance  in 
this  branch  of  dyeing.  They  are  also  useful  for  goods  that  may  be  sub- 
jected to  severe  treatment  with  alkalies,  such  as  fancy  silk  threads  running 
through  cotton  or  woolen  fabrics. 

The  substantive  colors  are  best  dyed  on  silk  with  the  addition  of  glauber- 
salt  and  acetic  acid,  or  in  a  bath  containing  boiled-off  liquor.  If  the  dye- 
ing is  done  without  the  latter,  add  to  the  bath  for  pale  shades  about  5  per 
cent  and  for  heavy  shades  about  10  per  cent  of  glaubersalt,  and  only  a 
small  quantity  (from  1  to  4  per  cent)  of  acetic  acid  at  the  beginning  of  the 
operation.  If  the  color  goes  on  the  fiber  too  slowly,  a  little  more  acetic 
acid  may  be  gradually  added  during  the  dyeing  process.  This  precaution 
is  necessary  because  it  is  difficult  to  obtain  level  colors  if  the  bath  is  too 
acid  at  the  beginning.  For  the  same  reason  it  is  also  important  not  to 
start  the  dyeing  at  too  high  a  temperature.  It  is  best  to  commence  at  120° 
F,  and  slowly  raise  to  the  boil.  For  shading  let  the  bath  cool  to  140  to 
160°  F.,  then  add  the  necessary  color  solution  and  gradually  heat  up  again. 
When  dyeing  light  colors  the  baths  exhaust,  as  a  rule,  with  the  addition  of 
glaubersalt  only,  or  with  a  very  little  acetic  acid  added.  For  heavy  shades 
the  addition  of  2  to  10  per  cent  of  acetic  acid  is  necessary. 

When  dyeing  in  a  bath  containing  boiled-off  liquor,  for  light  shades 
the  liquor  need  only  be  slightly  acid,  but  for  heavy  shades  the  acidity 
should  be  greater.  The  bath  should  contain  about  one-tenth  of  its  volume 
of  boiled-off  liquor.  Since  alkalies  prevent  the  absorption  of  substantive 
dyes  by  the  silk,  the  use  of  too  much  boiled-off  liquor  would  make  the 
bath  too  alkaline  in  character  for  proper  neutralization.  The  brightening 
after  dyeing  may  be  done  with  either  acetic  or  sulphuric  acid,  and  the 
dyeings  may  be  shaded  in  this  bath  in  any  desired  manner.  The  fastness 
of  the  substantive  colors  on  silk  to  acids,  alkalies,  stoving,  and  light  cor- 
responds in  general  to  that  which  they  possess  when  dyed  on  wool.f 

The  substantive  dyes  are  especially  suitable  for  the  dyeing  of  satin 

*  The  colors  obtained  with  the  substantive  dyes  on  silk,  as  a  rule,  are  much  faster 
than  those  on  cotton;  in  fact,  they  are  about  of  equal  fastness  to  those  produced  on 
wool.  The  colors  are  usually  much  faster  to  water  than  those  obtained  with  the  acid 
dyes,  though  they  do  not  possess  the  same  brilliancy.  Most  of  the  substantive  dyes 
yield  rather  dull  shades.  These  colors,  however,  may  be  after-treated  with  basic  dyes 
to  furnish  brilliant  tones. 

t  The  processes  of  after-treatment  with  chrome  or  bluestone  may  also  be  used 
in  the  dyeing  of  these  colors  on  silk.  The  amount  of  chrome  used  should  not  be 
more  than  one-third  the  weight  of  the  dyestuff  employed.  The  use  of  too  much 
chrome  will  injure  the  luster  of  the  fiber.  The  substantive  dyes  may  also  be 
diazotized  and  developed  on  silk  in  practically  the  same  manner  as  on  cotton,  and 
this  process  is  used  quite  extensively  for  the  production  of  certain  shades,  especially 
on  goods  containing  both  silk  and  cotton  (such  as  hosiery) .  This  process  cannot  be 
used  on  wool,  as  the  wool  fiber  itself  is  susceptible  of  diazotization  and  becomes  rather 
highly  colored  thereby,  thus  spoiling  the  color  obtained  in  dyeing. 


302  SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

goods  (fabrics  containing  silk  and  cotton)  as  the  color  is  taken  up  simul- 
taneously on  both  fibers  from  a  single  bath.  A  full  discussion  of  this 
subject  will  be  taken  up  under  the  topic  of  dyeing  silk-cotton  fabrics. 

Red  substantive  dyes  that  are  sensitive  to  acids  may  be  dj'-ed  on  silk 
in  a  bath  containing  sodium  phosphate  (5  per  cent)  and  soap  (5  per  cent). 
It  is  well,  however,  to  avoid  the  use  of  acid-sensitive  dyes  (such  as 
Congo  Red  and  Benzopurpurine  4B)  and  use  only  those  having  proper 
fastness  to  acids  (such  as  Diamine  Scarlet  3B,  Benzo  Fast  Scarlet,  Erika, 
etc.).  Other  suitable  substantive  dyes  for  silk  are  Benzo  Orange,  Mikado 
Orange,  Chrysophenine  (especially  important  for  silk),  Chrysamine 
(which  must  be  dyed  in  a  bath  containing  sodium  phosphate  and  soap), 
Benzo  Azurine,  Diamine  Sky  Blue,  and  Diamine  Brown  V.  Some  of  the 
blacks  are  also  used,  especially  those  for  diazotizing  and  developing. 

3.  Experimental.  Exp.  114.  General  Method  of  Dyeing  Wool. — Those  colors  are 
usually  dyed  on  wool  in  a  neutral  bath  containing  either  glaubersalt  or  common  salt. 
Although  the  substantive  colors  are  primarily  dyes  for  use  on  cotton,  nevertheless,  they 
are  being  employed  to  a  considerable  extent  on  wool,  as  many  of  them  give  colors  of 
eminent  fastness.  Dye  a  skein  of  woolen  yarn  in  a  bath  containing  20  per  cent  of 
glaubersalt  and  3  per  cent  of  Diamine  Scarlet  3B.  Enter  at  140°  F.,  gradually  bring 
to  the  boil,  and  dye  at  that  temperature  for  one -half  hour,  then  wash  well  and  dry. 
Common  salt  may  be  used  in  the  bath  in  place  of  glaubersalt  and  has  the  same  effect. 
The  purpose  of  the  addition  of  these  neutral  salts  is  to  cause  a  better  penetration  and 
distribution  of  the  coloring  matter,  and  also  to  cause  a  better  exhaustion  of  the  dj^e- 
bath.  The  substantive  dyes,  as  a  rule,  are  very  soluble  in  water,  and  show  no  par- 
ticular tendency  to  go  on  the  fiber  unevenly,  hence  the  material  may  be  entered  at  com- 
paratively high  temperatures  without  the  danger  of  unevenness.  Also  due  to  its  good 
solubility  in  water,  the  dyestuff  does  not  give  complete  exhaustion  in  the  bath.  The 
substantive  dyes  do  not  produce  as  bright  or  as  full  shades  on  wool  as  the  basic  and 
acid  dyes.  Some  of  the  substantive  dyes,  especially  the  reds,  are  very  sensitive  to 
the  action  of  acids,  their  color  being  changed,  as  has  been  shown  in  the  previous  chapter, 
with  Congo  Red.  The  dyestuff  used  above,  however,  is  fast  to  acid,  as  may  be  shown 
by  moistening  a  small  sample  of  the  dyed  yarn  with  a  dilute  solution  of  sulphuric  acid, 
washing  and  drying.     Also  test  this  color  for  its  fastness  to  fulling. 

Exp.  115.  Use  of  Ammonium  Acetate  in  the  Dyebath. — The  use  of  this  salt  in  the 
dyebath  appears  to  give  better  exhaustion  and  also  to  make  the  color  faster  to  fulling. 
Dye  a  skein  of  woolen  yarn  in  a  bath  containing  5  per  cent  of  ammonium  acetate  and 
3  per  cent  of  Diamine  Green  G;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at 
that  temperature  for  one-half  hour.  Wash  and  dry.  The  ammonium  acetate,  on  boil- 
ing, decomposes  into  ammonia  (which  is  volatilized)  and  free  acetic  acid,  and  this  no 
doubt  helps  in  the  dyeing  of  the  wool.  Ammonium  acetate  may  be  readily  prepared 
by  mixing  ammonia  water  and  acetic  acid  in  the  following  proportions:  32  parts  of 
strong  ammonia  water  and  50  parts  of  acetic  acid  (1.031  sp.  gr.)  which  will  give  a  solu- 
tion containing  25  parts  of  ammonium  acetate.  Diamine  Green  gives  a  color  on  wool 
which  has  good  fastness  to  washing. 

Exp.  116.  Dyeing  in  a  Slightly  Acid  Bath. — Some  of  the  substantive  dyes  may  be 
applied  to  wool  in  slightly  acid  baths  in  much  the  same  manner  as  the  acid  dyes.  This 
method  is  especially  useful  for  the  production  of  two-color  effects  on  mixtures  con- 
taining wool  and  cotton.     Dye  a  skein  of  woolen  yarn  in  a  bath  containing  20  per  cent 


EXPERIMENTAL  STUDIES 


303 


of  glaubersalt,  4  per  cent  of  acetic  acid,  and  2  per  cent  of  Chrysophenine;  enter  at  140° 
F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour;  wash  and 
dry.  Acetic  acid  is  mostly  used  in  this  connection,  as  sulphuric  acid  is  too  strong  and 
is  liable  to  injure  the  color,  and  where  cotton  is  present  there  is  danger  of  the  latter 
fiber  being  tendered  by  the  incomplete  removal  of  the  acid,  whereas  acetic  acid,  being 
volatile,  is  easily  removed.  Chrysophenine  gives  a  good  yellow  color  on  wool  which  is 
exceedingly  fast  to  light;  to  show  this  expose  a  sample  to  light  for  thirty  days. 

Exp.  117.  Showing  the  Application  of  Substantive  Dyes  on  Union  Material. — 
Dye  a  skein  of  union  yarn  (containing  wool  and  cotton  threads  twisted  together)  in  a 
bath  containing  20  per  cent  of  glaubersalt,  4  per  cent  of  acetic  acid,  and  2  per  cent  of 
Chrysophenine;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  tempera- 
ture for  one-half  hour;  wash  well  and  dry.  It  will  be  found  that  both  fibers  will  be  dyed 
about  a  uniform  color.     Dye  a  second  skein  of  union  yarn  in  a  bath  containing  20  per 


'■ 

r  1  1 

1 

:  _»|- 

#■" 

i 

\ 

'^M^SLi'i^ 

ym-^r^- 

L       ^ 

L  4«  \:^ 

:im^'t 

)^_ 

^ 

W- 

1 

\r~~~—^r-- 

''- 

L 

..^^tk 

if 

Fig.  164. — Dyeing  Jig.     (Textile-Finishing  Machinery  Co.) 


cent  of  glaubersalt,  4  per  cent  of  acetic  acid,  2  per  cent  of  Chrysophenine  and  1  per  cent 
of  Acid  Violet.  Dye  in  the  usual  manner,  wash  well,  and  dry.  It  will  be  found  in  this 
case  that  the  wool  has  been  dyed  with  both  the  yellow  and  violet  colors,  giving  a  result- 
ant olive  green,  whereas  the  cotton  has  been  dyed  with  the  yellow  and  has  only  been 
slightly  tinted  with  the  violet,  so  that  a  two-color  effect  has  been  obtained.  Union 
dyes  are  especially  employed  for  dyeing  blacks  where  it  is  desirable  to  hide  the  cot- 
ton woven  in  with  the  wool.  As  a  rule,  the  cotton  dyes  better  at  low  temperatures 
than  the  wool,  and  the  wool  better  at  high  temperatures.  Dye  a  skein  of  union  (wool 
and  cotton)  yarn  in  a  bath  containing  300  cc.  of  water,  20  per  cent  of  glaubersalt, 
and  6  per  cent  of  Erie  Black;  enter  at  100°  F.,  and  dye  at  that  temperature  for  one-half 
hour;  then  wash  well  and  dry.  It  will  be  noticed  that  the  cotton  is  dyed  much  darker 
than  the  wool.     Dye  a  second  skein  of  union  yarn  in  a  similar  bath,  but  at  a  tempera- 


304  SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

ture  of  175°  F.  for  one-half  hour;  then  wash  well  and  drj-.  It  will  be  found  that  both 
fibers  are  nearly  the  same  depth.  Dj'e  a  third  skein  of  union  yarn  in  a  similar  bath,  but 
at  the  boil  for  one-half  hour;  then  wash  well  and  dry.  It  will  be  found  that  the  wool  is 
dyed  somewhat  darker  than  the  cotton.  Dye  a  fourth  skein  of  union  yarn  in  a  bath 
containing  300  cc.  of  water,  20  per  cent  of  glaubersalt,  and  8  per  cent  of  Union  Black  B; 
enter  at  120°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half 
hour.     Wash  well  and  dry.     Compare  the  color  obtained  on  the  two  fibers. 

Exp.  118.  After-treatment  with  Chrome. — This  treatment  is  for  the  purpose  of 
increasing  the  fastness  of  the  color  to  washing  and  light.  At  the  same  time  it  also  causes 
an  increase  in  the  depth  of  the  color.  Dye  two  test  skeins  of  woolen  yarn  in  a  bath 
containing  20  per  cent  of  glaubersalt,  10  per  cent  of  ammonium  acetate,  and  3  per  cent 
of  Diamine  Fast  Red  F;  enter  at  140®  F.,  gradually  raise  to  the  boil,  and  dye  at  that  tem- 
perature for  one-half  hour.  Remove  one  of  the  skeins,  wash,  and  dry.  Add  to  the  dye- 
bath  2  per  cent  of  chrome,  re-enter  the  second  skein  and  continue  boiling  for  twenty 


Fig.  165. — Circulating  Dyeing  Machine  for  Hosiery.     (Philadelphia  Drying  Machine 

Co.) 

minutes;  then  wash  and  dry.  Compare  the  colors  obtained  on  these  two  samples,  and 
test  each  skein  for  its  fastness  to  washing. 

Exp.  119.  After-treatment  with  Chromium  Fluoride. — This  salt  is  sometimes  sub- 
stituted for  chrome.  It  acts  in  much  the  same  manner  by  increasing  the  fastness 
of  certain  colors  to  light  and  washing,  and  also  deepening  the  shade.  As  it  is  not  a 
strong  oxidizing  agent  like  chrome,  it  may  be  used  at  times  where  the  latter  cannot. 
Dye  two  test  skeins  of  woolen  yarn  in  a  bath  containing  20  per  cent  of  glaubersalt  and 
3  per  cent  of  Direct  Green;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at 
that  temperature  for  one-half  hour.  Remove  one  of  the  skeins,  and  wash  and  dry. 
Add  to  the  dyebath  3  per  cent  of  chromium  fluoride,  re-enter  the  second  skein  and  boil 
for  twenty  minutes  longer;  then  wash  and  dry.  Compare  the  two  skeins  with  respect 
to  their  color  and  make  tests  on  each  to  determine  the  fastness  to  washing. 

Exp.  120.  Example  of  a  Substantive  Dye  not  Coloring  Wool. — There  are  a  few  of  the 
substantive  dyes  which  are  not  taken  up  by  the  wool  fiber,  especially  if  the  bath  is  at  a 
comparatively  low  temperature  and  is  slightly  alkaline.  Dye  a  test  skein  of  woolen 
yarn  in  a  bath  containing  20  per  cent  of  glaubersalt,  1  per  cent  of  soda  ash,  and  2  per 
cent  of  Mikado  Yellow;  enter  at  100°  F.,  gradually  raise  to  120°  F.,  and  dye  at  that  tem- 
perature for  one-half  hour;  then  wash  well  and  dry.     It  will  be  found  that  the  wool  is 


EXPERIMENTAL  STUDIES 


305 


hardly  tinted  by  this  color.     On  this  account,  such  dyes  are  very  useful  for  the  dyeing  of 
union  materials  where  it  is  desirable  to  leave  the  wool  undyed. 

Exp.  121.  General  Method  of  Applying  Substantive  Dyes  to  Silk. — This  fiber,  like 
wool,  will  dye  very  readily  with  many  of  the  substantive  colors,  yielding  shades  which  are 
fast  to  washing  and  water  and  in  many  cases  fast  to  light.  Dye  a  skein  of  silk  in  a  bath 
containing  10  per  cent  of  soap  (or  a  boiled-off  liquor  bath  may  be  employed  where  this  is 
available)  and  3  per  cent  of  Benzo  Fast  Scarlet;  enter  at  140°  F.,  gradually  raise  to  the 
boil  and  dye  at  that  temperature  for  one-half  hour.  Wash  well  and  dry.  Silk  may  also 
be  dyed  in  a  slightly  acid  bath,  as  with  wool.  Dye  a  skein  of  silk  in  a  bath  containing 
3  per  cent  of  Chrysophenine,  10  per  cent  of  glaubersalt,  and  4  per  cent  of  acetic  acid; 
enter  at  140°  F.,  bring  to  180°  F.,  and  dye  at  that  temperature  for  one-half  hour.     Wash 


Fig.  166. — Padding  Machine  for  Dyeing  Cotton  Cloth. 

well  and  dry.  As  with  wool,  silk  dyed  with  the  substantive  colors  may  be  after-treated 
with  chrome,  etc.,  in  order  to  obtain  faster  shades.  The  substantive  colors  are  also 
very  useful  in  the  dyeing  of  half-silk  (silk  and  cotton  fabrics),  both  for  single  colors  and 
for  the  production  of  two-color  effects,  in  the  same  manner  as  already  described  under 
their  application  to  wool. 

Exp.  122.  Representative  Substantive  Dyes. — Dye  skeins  of  cotton  yarn  in  baths 
containing  1  per  cent  of  soda  ash,  20  per  cent  of  common  salt  and  2  per  cent  of  the 
respective  dyes  named  below;  enter  at  160°  F.,  bring  to  the  boil,  and  dye  at  that  tem- 
perature for  one-half  hour,  then  wash  and  dry.     Use  the  following  dyestuffs: 


(1)  ThioflavineS 

(2)  Diamine  Brown  3G 

(3)  Diamine  Bordeaux  B 


(4)  Diamine  Orange  D 

(5)  Chicago  Blue  6B 

(6)  Columbia  Black  FB 
(10)  Dianil  Green  G 

Test  these  dyeings  for  fastness  to  washing  and  water. 


(7)  Diamine  Rose  BD 

(8)  Benzo  Fast  Scarlet 

(9)  DianU  Blue  G 


306  SUBSTANTIVE  DYES  ON  WOOL  AND  SILK 

Make  a  record  of  the  results  as  follows: 


Washing. 

Water. 

Dyestuff. 

White 
wool. 

White 
cotton. 

Water. 

White 
cotton. 

Water. 

.  .  :     

....                1 

' 

4.  Principal  Substantive  Dyes  Applicable  to  Wool 


Alkali  Orange  Chrysophenine  G 

Azo  Violet  Columbia  Fast  Scarlet  4B 

Benzo  Azurine  G,  3G  Columbia  Green 

Benzo  Blue  BX,  RW,  2R,  4R  Columbia  Violet  R 
Benzo  Brown  B,  NB,  G,  2G,  Congo  Brown  G,  R 

5R  Congo  Corinth  G,  N 

Benzo  Bordeaux  6B  Congo  Orange  G,  R 

Benzo  Chrome  Brown  B,  G,  Congo  Red  4R 


R 

Benzo  Cyanine  B,  R 
Benzo  Dark  Green  B,  2G 
Benzo  Fast  Black 
Benzo  Fast  Blue  5R 
Benzo  Fast  Orange  S 
Benzo  Fast  Red  L,  GL 


Congo  Rubine 
Cotton  Brown  I,  II,  III 
Cotton  Orange  G,  R 
Cresotine  Yellow  G 
Curcumine  S 
Delta  Purpurine  oB 
Diamine  Black  HW 


Benzo  Fast  Scarlet  4BS,  8BS  Diamine  Blue  RW,  3B,  2B 
GS 


Diamine  Steel  Blue  L 
Diamine  Violet  N 
Diamine  Y'ellow  CP 
Diaminogene  extra 
Dianil  Black  N,  E 
Dianil  Black  T 
Dianil  Blue  BX 
Dianil  Bro^-n,  3G0,  3R 
Dianil  Claret  Red  G,  B 
Dianil  Copper  Brown  O 
Dianil  Green  G 
Dianil  Indigo  O 
Dianil  Orange  N 
Dianil  Red  R,  4B,  lOB 
Dianil  Scarlet  G,  2R 
Dianil  Yellow  G 


Benzo  Fast  Violet  R 
Benzo  Fast  Yellow  oG 
Benzo  Green  B,  R 
Benzo  Orange  R 
Benzopurpurine  4B 


Diamine  Brown  3G,  R,  M,  B  Dianil  Yellow  3G,  R,  2R 

Diamine  Bordeaux  B,  S  Diazo  Black  B,  R.  3B 

Diamine  Brilliant  Bordeaux  Diazo  Fast  Black  SD 

R  Diphenyl  Citronine 

Diamine  Brilliant  Scarlet  S  Diphenyl  Fast  Yellow 


Diamine  Catechine  G 


Benzo  Rhoduline  Red  B,  3B  Diamine  Fast  Red  F 
Benzo  Violet  R,  RL  Diamine  Fast  Yellow  FF 

Bordeaux  COV  Diamine  Gold 

BrilUant  Azurine  B,  G,  oG  Diamine  Green  G,  B,  CL 


BrilUant  Congo  R 
BriUiant  DianU  Red  R 
Brilliant  Geranine  B,  3B 
Brilliant  Orange  G 
BriLUant  Purpurine  lOB 
Carbazol  Yellow 
Chicago  Blue  B,  6B 
Chicago  Blue  2R,  4R 
Chloramine  Orange  G 
Chrysamine  G,  R 


Diamine  Jet  Black  00 
Diamine  Orange  B,  F 


Direct  Blue  Black  B.  2B, 
Direct  Fast  Brown  B 
Eboli  Green  S,  ST 
Erica  B,  G,  2GN 
Geranine  2B,  G 
Hessian  Bordeaux 
Hessian  Brilliant  Purple 


N 


Diamine  Purpurine   B,    3B,  Hessian  Purple  N 


6B 

Hessian  Violet 

Diamine  Red  B 

Hessian  Yellow 

Diamine  Red  4B,  6B,  lOB 

Mikado  Orange 

Diamine    Rose    GD,     BG, 

Nvanza  Black  B 

BD,  B 

Orange  TA 

Diamine  Scarlet  B,  3B 

Oxvdiamine  Bro\VTi  G 

Diamine  Sky  Blue  FF 

Oxydiamine  Orange  G,  R 

DYES  SUITABLE   FOR  SILK 


307 


Oxydiamine  Violet  B,  G,  R 
Oxydiaraine  Yellow  TZ 
Pegu  Brown 

Pluto  Brown  2G,  NB,  R 
Pluto  Orange  G 


Polyphenyl  Yellow 
Rose  Azurine  B,  G 
Salicine  Yellow 
Sun  Yellow 
Thiazole  Yellow  G,  R 


Aurophenine  O 

Azo  Blue 

Azo  Violet 

Benzo  Azurine  G,  R 

Benzo  Blue  2B,  RW 

Benzo  Brown  B,  G,  R 


5.  Substantive  Dyes  Suitable  for 

Chicago  Blue  6B,  4B,  B,  RW 
Chicago  Blue  R,  2R 
Chloramine  Orange  G 
Chloramine  Violet  R 
Chloramine  Yellow  GG 
Chrysamine  G,  R 


Benzo  Chrome  Brown  B,  G,  Chrysophenine  G 


R 
Benzo  Cyanine  3B 
Benzo  Dark  Green  B,  2G 
Benzo  Fast  Black 
Benzo  Fast  Blue  B,  5R 
Benzo  Fast  Gray 
Benzo  Fast  Orange  S 
Benzo  Fast  Pink  2BL 
Benzo  Fast  Red  GL 
Benzo  Fast  Scarlet  4BS 
Benzo  Fast  Violet  R 
Benzo  Fast  Yellow  5GL 
Benzo  Green  2B,  G 
Benzo  Indigo  Blue 
Benzo  Olive 
Benzopurpurine  4B 
Benzo  Red  SG 
Benzo  Rhoduline  Red  B 
Benzo  Sky  Blue 
Benzo  Violet  R,  RL 


Columbia  Brown  R 
Columbia  Fast  Scarlet  4B 
Columbia  Green 
Columbia  Violet  R 
Columbia  Yellow 
Congo  Brown  G,  R 
Congo  Corinth  G,  B 
Congo  Orange  G,  R 
Congo  Rubine 
Cotton  Brown  I,  II,  III 
Curcumine  S 
Delta  Purpurine  5B 
Diamine  Blue  BX,  2B 
Diamine  Blue  RW 
Diamine  Bordeaux  S 
Diamine  Brown  3G,  R,  B 
Diamine  Dark  Blue  B 
Diamine  Fast  Blue  G 
Diamine  Fast  Brown  G,  R 
Diamine  Fast  Red  F 


Brilliant  Azurine  B,  5G,  2R  Diamine    Fast    Yellow    B, 


Brilliant  Benzo  Blue  6B 
Brilliant  Benzo  Green  B 
Brilliant  Congo  R 
Brilliant  Dianil  Red  R 
Brilliant  Geranine  B 
Brilliant  Orange  G 


FF,  M 
Diamine  Gray  G 
Diamine  Green  B,  CL,  G 
Diamine  Orange  F,  G,  D 
Diamine  Red  B 
Diamine  Rose  BD,  BG 


Brilliant  Purpurine  R,  lOB     Diamine  Scarlet  B,  3B 
Brilliant  Sulphon  Azurine  R  Diamine  Sky  Blue 
Catechu  Brown  DX 


Thioflavine  S 
Toluylene  Orange  G,  R 
Wool  Brown  G,  R 
Zambesi  Black  D,  F 

Silk 

Diamine  Steel  Blue  L 
Diamine  Violet  N,  2B 
Diamine  Yellow  CP 
Diamineral  Brown  G 
Diaminogene  extra 
Dianil  Blue  G,  B,  R 
Dianil  Brown  3G0,  4,  BD 
Dianil  Orange  G,  N 
Dianil  Red  4B 
Dianil  Yellow  R,  3G 
Diazo  Black  B,  R 
Diazurine  B 
Direct  Blue  Black  B 
Direct  Bronze  Brown 
Direct  Fast  Brown  B 
Direct  Yellow  R 
Erica  B 

Geranine  2B,  G 
Heliotrope  BB 
Hessian  Purple  N 
Janus  Brown  R 
Janus  Red  B 
Janus  Yellow  G,  R 
Mikado  Orange  GO,  4R0 
Neutral  Gray  G 
Oxydiamine  Black  FFC,  JB 
Oxydiamine  Brown,  3GN 
Oxydiamine  Violet  B,  R,  G 
Pluto  Black  A,  F 
Pluto  Orange  G 
Rose  Azurine  B,  G 
Salmon  Red 
Thioflavine  S 
Toluylene  Orange  G 
Zambesi  Black  D 
Zambesi  Brown  G 


CHAPTER  XV 
DEVELOPED  DYES  ON  COTTON  AND  SILK 

1.  The  Production  of  Developed  Colors  on  Cotton, — The  defect  of 
the  substantive  dyes  on  cotton  is  their  UabiUty  to  bleed  when  washed, 
although  this  may  be  remedied  in  some  cases  by  an  after-treatment  with 
certain  metallic  salts;  still  faster  dyeings  may  usually  be  obtained  by  the 
cUazotizing  and  developing  process.  This  process  is  more  especially 
employed  for  the  production  of  Primuline  Red  as  a  substitute  for  the  more 
expensive  Turkey  Red,*  and  for  the  production  of  fast  blacks;  the  other 
colors  are  not  so  much  used.  The  developing  process  not  only  materially 
increases  the  fastness  of  the  colors  to  wasliing  and  acids  but  it  also  greatly 
increases  the  intensitj^  of  the  shade. f  It  has  already  been  noted  that  the 
substantive  colors  do  not  j-icld  very  deep  shades  on  cotton,  even  when 
large  amounts  of  dyestuff  are  used  in  the  bath;  in  many  cases  the  blacks 
when  dyed  direct  give  only  dark  blue  or  slate  colors,  and  produce  only  a 
deep  black  on  being  diazotized  and  developed. t  Not  all  of  the  substantive 
dyes  may  be  developed,  but  a  sufficient  nimiber  of  them  are  susceptible  to 
tliis  treatment  to  give  a  M-ide  range  of  shade,  and  there  are  a  number  of 
the  dyes  wliich  diazotizing  does  not  affect,  and  which  maj^  in  consequence 
be  used  for  purposes  of  shading,  being  added  directly  to  the  same  dye- 
bath  as  the  developed  color. 

The  dyeing  of  developed  colors  is  distinctly  a  chemical  operation 
whereby  one  dyestuff  is  changed  into  another  on  the  fiber.  §  The  nitrous 
acid  of  the  diazotizing  bath  converts  the  amino  group  of  the  first  dye- 
stuff  into  an  unstable  azo  body,  which  is  subsequently  combined  with  a 

*  This  process  seems  to  have  first  been  employed  bj^  the  Enghsh  chemist  Green  in 
1887  using  Primuhne,  a  dye  which  he  had  discovered. 

t  The  fastness  to  washing  of  the  colors  obtained  by  diazotizing  and  developing  is,  as 
a  rule,  very  good.  With  the  same  dyestuff,  however,  the  fastness  may  vary  consider- 
ably with  different  developers.  Primuline,  for  example,  developed  with  beta-naphthol 
gives  a  color  somewhat  faster  to  washing  than  w^hen  developed  with  phenylene-diamine 
or  with  phenol.  In  fastness  to  light  the  developed  colors,  in  general,  are  about  the  same 
as  the  dyes  from  which  they  are  derived.  The  diazotizing  and  developing  process  does 
not  appear  to  increase  the  fastness  of  the  color  in  this  respect.  In  fastness  to  acids  the 
developed  colors,  as  a  rule,  are  very  good,  and  may  be  used  very  satisfactorily  for 
purposes  of  cross-dyeing. 

X  In  order  that  a  substantive  dye  may  be  suitable  for  diazotizing,  it  is  necessary 
that  it  contain  a  free  amino  group  ( — NHo)  in  the  molecule. 

§  On  this  account  the  developed  dyes  were  frequently  spoken  of  as  "ingrain"  colors 

308 


DIAZOTIZING  PROCESS  309 

"  developer  "  to  form  a  stable  azo  dyestuff.  The  operation  may  be  repre- 
sented by  the  following  schematic  equations: 

RNH2+N0-0H+HC1  =  RN  :  NCI+2H2O 

Primuline  or  Nitrous  Hydro-  Diazo  body.        Water 

other  dyestuff.  Acid.  chloric 

Acid 

RN  :  NCl+CioH70H  =  RN  :  NCioHgOH+HCI 

Diazo  Body  Bcta-naphthol  Developed  Color 

Developer. 

From  this  it  may  be  seen  that  the  Primuline  is  converted  into  another 
totally  different  body.  The  diazotizing  and  developing  reactions  are 
also  very  largely  employed  for  the  production  of  the  majority  of  the  sub- 
stantive dyes  themselves,  without  any  reference  to  the  fiber. 

Although  there  are  quite  a  number  of  dyestuffs  (and  other  bodies  as 
well)  that  are  capable  of  undergoing  the  above  reactions,  yet  there  are  but 
a  limited  nmnber  with  which  the  process  may  be  used  to  give  the  desired 
results.  The  developed  color  must  be  faster,  or  possess  other  exception- 
able qualities,  and  to  this  end  it  is  necessary  that  the  new  dye  prepared 
on  the  fiber  be  insoluble  and  also  possess  satisfactory  tinctorial  properties. 
The  properties  of  some  dyes  are  not  affected  by  the  diazotizing  and  devel- 
oping processes,  while  others  have  their  fastness  very  much  increased 
without  any  great  alteration  in  the  color;  the  general  tendency  of  the 
process,  however,  is  to  considerably  deepen  the  shade. 

^t  must  be  borne  in  mind  that  developed  colors  require  three  differ- 
ent operations  and  as  .nany  different  baths;  this  necessitates,  of  course,  a 
triple  handling  of  the  cotton  and  therefore  a  greater  expense  than  when 
dyejng  the  substantive  colors  alone.  There  is  nothing  different  in  the  first 
dyeing  process  of  the  developed  colors  beyond  that  of  the  ordinary  sub- 
stantive dyes,  Xvhich  have  already  been  discussed.  The  second  opera- 
tion, that  of  aiazotizing,  is  the  same  for  all  the  developed  colors,  and  con- 
sists in  working  the  dyed  and  rinsed  cotton  in  a  cold  bath  containing 
^odiu^^jlitnte^nd  hydrochloric  acid;  the  operation  requires  only  ten  to 
fifteen  minutes.  After  diazotizing  it  is  well  to  rinse  the  goods  in  water 
slightly  acidulated  with  hydrochloric  acid.  The  third  operation,  that  of 
di^veloping,  is  also  done  in  a  cold  bath  and  requires  only  from  ten  to  fif- 
teen minutes ;  the  kind  of  developer  *  used  depending  on  the  dyestuff 
employed  and  the  color  desired. 

*  When  developers  of  a  phenol  character  are  employed  (such  as  beta-naphthol)  it  is 
necessary  to  first  dissolve  them  in  a  little  hot  water  containing  caustic  soda  or  soda  ash 
(about  the  same  amount  as  developer  used),  and  the  developing  bath  should  always 
be  somewhat  alkaline  in  character,  as  a  small  amount  of  acid  is  alwaj's  carried  over  in 
the  goods  from  the  diazotizing  bath;  hence  in  a  standing  bath  of  developer  it  is  neces- 
sary to  add  from  time  to  time  a  small  amount  of  alkali,  sodium  acetate  being  the  most 
suitable  salt  to  employ.  When  amino  developers  are  used  (such  as  meta-phenylene- 
diamine),  if  they  are  not  alreadj-  in  the  forms  of  salts  (as  amines  are  of  a  basic  character), 
they  must  first  be  dissolved  in  hydrochloric  acid.  This  is  most  conveniently  done  by 
adding  the  acid  to  the  amine  suspended  or  melted  in  water. 


310 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


A  diazotizing  Ixath  for  10  lbs.  of  cotton  can  lx>  prepar«d  with  ^  lb.  sodium 
nitrite  and  |  lb.  hydrochloric^  acid  (of  32°  Tw.);  sulphuric  acid  may  be 
used  in  place  of  hydrochloric,  in  which  case  only  |  lb.  of  acid  (of  168°  Tw.) 
is  employed.  In  preparing  the  bath  the  nitrite  should  first  be  dissolved 
in  some  water,  added  to  the  bath,  after  which  the  acid  is  added.*  For 
standing  baths  only  one-third  of  the  above  mentioned  quantities  is  used. 
In  order  to  ascertain  if  the  diazotizing  bath  is  still  active,  dip  into  it  a 
piece  of  paper  impregnated  with  starch  paste  and  potassium  iodide,  which 
should  at  once  turn  blue.     When  working  the  bath  it  should  smell  dis- 


FiG.  167. — Centrifuge  for  Cloth.     (Heine.) 

tinctly  of  nitrous  acid,  though  the  odor  should  not  be  too  pungent,  wliich 
would  indicate  an  excess  of  nitrite.  This  is  not  necessarily  injurious, 
but  should  be  avoided  for  reasons  of  economy.  The  diazotizing  is  best 
conducted  in  wooden  vessels,  though  when  dyeing  in  machines  the  diazo- 
tizing and  developing  may  take  place  in  copper  vessels.  It  is  not  neces- 
*  Based  on  the  weight  of  the  cotton  the  following  proportions  are  recommended  for 
the  diazotizing  bath: 

For  Pale  or         For  Heavy 
Medium  Shades        Shades 
Per  Cent  Per  Cent 

Sodium  nitrite I2  2^ 

Hydrochloric  acid 5  71 

or  Sulphuric  acid 3  5 

The  dj'^ed  cotton  is  rinsed  in  cold  water  and  then  worked  for  fifteen  minutes  in  the  cold 
diazotizing  bath.  The  goods  are  then  once  lightly  riii.scd  in  water  acidulated  with  hydro- 
chloric acid  and  developed  without  delay.  When  diazotizing  in  machines  or  the  jigger, 
smaller  amounts  of  nitrite  and  acid  will  usually  be  found  sufficient. 


DEVELOPERS 


311 


sary  to  hydro-extract  or  wring  out  after  diazotizing;  the  goods  are  allowed 
to  drain,  and  then  rinsed  slightly  in  water  acidulated  with  1  pint  of  hydro- 
chloric acid  to  100  gallons,  and  then  entered  directly  into  the  developing 
bath.  It  is  also  important  to  remember  that  the  diazotized  goods  should 
not  be  left  standing  for  any  length  of  time,  but  the  rinsing  and  developing 
should  proceed  immediately  after  the  diazotizing.  Especial  care  should  be 
taken  not  to  expose  the  diazotized  color  to  glaring  light  or  to  any  source 
of  heat. 

The  developing  bath  is  prepared  with  cold  water  and  the  requisite 
amount  of  developer  in  solution.  The  goods  are  turned  a  few  times  in 
this  bath,  then  taken  out  and  rinsed  off. 

2.  Developers. — The  principal  developers  in  use  are  beta-naphthol 
and  phenylene-diamine.  The  latter,  however,  is  usually  a  mixture  con- 
taining more  or  less  toluylene-diamine,  the  action  of  which  is  practically 
the  same. 

The  beta-naphthol  solution  for  developing  may  be  prepared  conveni- 
ently by  dissolving  7  lbs.  3  ozs.  of  beta-naphthol  and  6  lbs.  caustic  soda 
(of  77°  Tw.)  in  10  gallons  of  boiling  water;  for  each  10  lbs.  of  cotton  devel- 
oped use  1^  pints  of  this  solution.*     For  phenylene-diamine  or  toluylene- 

*  The  following  methods  of  preparing  some  other  developers  are  recommended: 


Developer. 

Amount  Dissolved  in 
10  Gallons  of  Boiling  Water. 

Amount  of  Sol 
10  lbs.  ( 

u.ion  Used  for 
Z^otton. 

Light  Shades. 

Heavy  Shades. 

Naphthylamine    Ether    powder 

2  lbs.  4|  OZS.  with  1  lb. 
2  ozs.  hydrochloric  acid 

3?  pints. 

6^  pints. 

Naphthylamine  Ether  N  powder 

2  lbs.  4^  ozs.  with    \ 
pint    of    hydrochloric 
acid 

3  J  pints 

6|  pints 

Fast  Blue  Developer  AN 

131  ibg 

I  pint 

1§  pints 

Fast  Blue  Developer  AD 

3  lbs.  llozs.withlUbs. 
of  hydrochloric  acid 

2  pints 

4  pints 

Resorcine 

51  lbs.  with  12  lbs.  of 
caustic  soda,  77°  Tw. 

1  pint 

I5  pints 

Phenol 

4  lbs.  11  ozs.  with  12  lbs. 
of  caustic  soda,  77°  Tw. 

i  pint 

Ij  pints 

Bordeaux  Developer 

2  lbs.  4|  ozs.  with    \\ 
pints    of    hydrochloric 
acid 

3i  pints 

6^  pints 

312  DEVELOPED  DYES  ON  COTTON  AND  SILK 

diamine,  dissolve  4|  lbs.  of  the  salt  with  1|  lbs.  of  soda  ash  in  10  gallons 
of  boiling  water,  and  1|  pints  of  this  solution  is  sufficient  for  10  lbs.  of 
cotton.*  If  the  baths  are  used  repeatedly,  the  above  quantities  are  used 
for  the  first  two  or  three  lots,  after  which  only  three-fourths  the  amounts 
are  taken,  f  The  amount  of  water  in  the  diazotizing  and  developing  baths 
should  be  about  twenty  tmies  the  weight  of  the  cotton.  An  addition  of 
bluestone  to  the  diazotizing  bath  increases  the  fastness  to  light  of  the  color 
in  most  cases;  for  such  purpose,  however,  it  is  best  to  give  an  after-treat- 
ment with  bluestone  after  developing,  by  passing  the  goods  through  a 
cold  or  lukewarm  bath  containing  3  per  cent  of  bluestone  and  3  per  cent  of 
acetic  acid,  and  then  rinsing.  After  development  or  after  this  treatment 
the  cotton  is  usually  soaped  or  oiled  for  the  purpose  of  softening.  Devel- 
oped dyeings  may  be  topped  with  basic  dj'es  in  the  same  manner  as  the 
direct  dyeings  with  substantive  colors. 

By  combining  the  same  dyestuff  with  different  developers  a  variety  of 
colors  may  be  obtamed ;  for  example : 

Primuline  with  beta-naphthol  =  red ; 
Primuline  with  alpha-naphthol  =  claret-red; 
Primuline  Anth  phenol  =  yellow ; 
Primuline  with  resorcine  =  brown ; 
Primuline  with  phenylene-diamine  =  red-brown. 

In  the  dyeing  of  blacks  'u-ith  phenylene-diamine  as  the  developer  a 

bluer  tone  may  be  given  by  adding  a  small  cjuantity  of  beta-naphthol  to 
the  developing  bath.     Care  must  be  had,  however,  in  thus  mixing  devel- 

*  The  quantities  of  the  different  developers  required  may  be  calculated  on  the 
following  basis: 

For  Developing  of 
2  Per  Cent         4  to  5  Per  Cent 
Developer.  Dyeings.  Dyeings. 

Per  Cent  Per  Cent 

Beta-naphthol 0.45  0.90 

Naphthylamine  Ether  powder 0 .  75  1 .  50 

Naphthylamine  Ether  N 0 .  75  1 .  50 

Blue  Developer  AN 1 .00  2.00 

Fast  Blue  Developer  AD 0. 75  1 .50 

Resorcine 0.35  0.70 

Phenylene-diamine  powder 0.35  0.70 

Phenol 0.25  0.50 

Bordeaux  Developer. : 0 .  50  1 .  GO 

t  Care  should  be  taken  not  to  employ  too  large  an  amount  of  developer  in  dyeing, 
and  this  is  especially  true  in  the  case  of  blacks  obtained  with  phenj'lene-  or  toluylene- 
diamine.  The  excess  of  developer  which  does  not  react  with  the  diazo  body  will  remain 
in  the  goods  and  on  ex-posure  to  air  will  turn  brown,  thus  giving  a  dull  rusty  tone  to  the 
black  color,  and  also  causing  excessive  bleeding  when  washed  with  white  cotton.  On  the 
other  hand,  the  use  of  too  small  a  quantity  of  developer  will  cause  the  color  to  lack  full- 
ness— have  a  so-called  "  hungry  "  look — and  also  to  have  inferior  fastness  to  washing. 


DEVELOPERS  313 

opers,  as  some  do  not  work  well  with  others.     The  following,  however, 
can  be  used  together. 

Beta-naphthol  with  resorcine; 
Beta-naphthol  with  phenylene-diamine ; 
Beta-naphthol  with  toluylene-diamine ; 
Phenylene-diamine  with  resorcine; 
Toluylene-diamine  with  resorcine; 
Naphthylamine  ether  with  Fast  Blue  Developer  AD. 

A  few  of  the  diazotized  colors  may  be  developed  in  another  manner 
than  that  indicated  in  the  foregoing.  Primuline,  for  instance,  may  be 
developed  by  treating  in  a  lukewarm  bath  (100°  F.)  containing  soda  ash 
(2^  to  5  per  cent,  according  to  depth  of  shade) ,  a  yellow  color  of  fairly  good 
fastness  being  obtained.  Diamine  Cutch  may  also  be  developed  in  this 
manner.*  Another  variation  in  the  method  of  developing  is  to  treat  with 
a  cold  dilute  (^°  Tw.)  solution  of  bleaching  powder.  Primuline  treated 
in  this  manner  gives  a  yellow  color  of  great  fastness  to  light,  washing,  cross 
dyeing  and  even  to  bleaching.  The  same  method  is  used  independently 
of  dyeing  for  the  manufacture  of  a  yellow  dyestuff  (Chloramine  Yellow). 

The  following  is  a  list  of  the  principal  developers  with  their  common 
trade  names: 

1.  Beta-naphthol,  frequently  known  just  as  "  naphthol  "  =  Red  Developer,  Dye 
Salt  II. 

2.  Sodium  salt  of  beta-naphthol,  frequently  not  distinguished  from  the  above  = 
Developer  A. 

3.  Beta-naphthol-7-sulphonic  acid  (sodium  salt);  this  is  known  as  "  F-acid,"  or 
"  mono-sulphonic  acid,"  or  "  shading  salt." 

4.  Naphthol  R;  this  is  a  mixture  of  beta-naphthol  with  10  per  cent  of  F-acid;  it 
gives  a  bluer  tone  of  red  than  beta-naphthol  alone  in  developing  Primuline  or  Para  Red  = 
Dye  Salt  1. 1 

5.  Resorcine  =  Developer  F,  Orange  Developer,  Dye  Salt  VI. 

6.  Phenol  =  Developer  J,  Yellow  Developer,  Dye  Salt  VII. 

7.  Meta-phenylene-diamine  hydrochloride  =  Developer  C.  Brown  Developer,  Dye 
Salt  V. 

8.  Meta-phenylene-diamine  base  =  Developer  E. 

9.  Meta-toluylene-diamine  base  =  Developer  H. 

10.  Ethyl-beta-naphthylamine  =  Naphthylamine  Ether,  Developer  B. 

11.  Amino-diphenylamine  =  Fast  Blue  Developer  AD. 

12.  Amino-naphthol-sulphonic  acid  G  =  Blue  Developer  AN,  Developer  G. 

13.  Alpha-naphthol  =  Maroon  Developer. 

14.  Alpha-naphthol-para-sulphonic  acid  =  Crimson  Developer. 

*The  diazotized  goods  are  entered  directly  into  the  alkali  bath  without  a  previous 
rinsing,  and  worked  for  about  fifteen  minutes,  after  which  they  are  rinsed  and  soaped  in 
the  usual  manner. 

t  As  Naphthol  R  contains  a  sulphonic  acid  the  red  dyestuff  produced  is  more  sol- 
uble than  that  with  beta-naphthol  alone,  and  hence  is  less  fast  to  soaping. 


314 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


15.  Alpha-naphthol-suli)honic  acid  R  =  Dye  Salt  IV. 

16.  Beta-naphthol-disulphonic  acid  =  Maroon  Developer. 

17.  Dioxy-naphthalene  =  Developer  D. 

18.  Diamino-azobenzene  hydrochloride  =  Chrysoidine. 

19.  Naphthol  AS;  this  is  beta-oxy-naphthoic  acid  anilide,  C,oH6(OH)(CO  •  NH  -CeHj). 
It  is  used  particularly  as  a  developer  for  the  naphthol  class  of  dyes. 

20.  Nerogene  D  is  a  chlorinated  diamine. 

The  usual  developers  consist  of  amines  or  phenols  (or  naphthols)  or 
sulphonic  acid  derivatives  of  these.  When  using  toluylene-diamine,  as 
this  is  ver}'  sensitive  to  oxidation,  in  order  to  prevent  the  development  of  a 
brown  tone  it  is  necessary  to  make  the  first  wash  water  slightly  acid  so 
that  any  residues  of  the  developer  may  be  dissolved  and  removed. 

The  shade  of  color  developed  from  any  particular  dj'estuff  varies 
considerably  with  the  different  developers;  this  may  be  shown  by  a  con- 
sideration of  the  action  of  different  developers  on  Primuline: 


Beta-naphthol 

gives 

red 

Rsalt 

gives 

maroon 

NW  salt 

gives 

crimson 

Resorcine 

gives 

orange 

Phenol 

gives 

yellow 

Meta-phenylene-diamine 

gives 

brown 

Alpha-naphthj'lamine 

gives 

purple 

Naphthylamine  ether 

gives 

blue 

Ethyl-beta-naphthylamine 

gives 

maroon 

Beta-naphthol-sulpho  acid  S 

gives 

red 

Benzidine 

gives 

dull  drab  yellow 

Salicylic  acid 

gives 

j'cllow 

Caustic  soda 

gives 

dull  yellow 

Amino-diphenylamine 

gives 

pale  green 

Dianisidine 

gives 

pale  green 

Dioxy-naphthalene 

gives 

gray 

These  colors,  however,  are  by  no  means  of  equal  importance;  the  alpha- 
naphthjdamine  purple,  for  example,  is  very  fugitive  to  light;  the  blue 
from  naphthjdamine  ether  is  not  fast  to  washing,  etc.  In  practice  this 
greatly  curtails  the  range  of  shades  obtainable  from  Primuline,  the  beta- 
naphthol  red  being  by  far  the  most  importanty 

3.  Methods  of  Shading  Developed  Dyes.-^From  a  consideration  of  the 
process  by  which  developed  dyes  are  applied  it  will  be  readily  under- 
stood that  the  intensity  or  depth  of  the  color  obtained  will  depend  entirely 
upon  the  amount  of  color  fixed  in  the  first  operation,  since  the  diazotizing 
and  developing  baths  must  always  contain  an  excess  of  the  reagents. 
This  fact  presents  certain  difficulties  in  the  way  of  readily  matching 
shades  to  a  sample,  particularly  as  there  may  be  no  combination  of  dye 
and  developer  that  may  jdeld  the  exact  shade  required.  A  number  of 
methods,  however,  may  be  employed  for  the  purpose  of  modifying  the  shade 


SHADING   DEVELOPED   DYES 


315 


of  any  particular  developed  dyeing  in  order  to  match  any  desired  shade. 
These  methods  may  be  summarized  as  follows: 


O 


13 


Q 

-a 
a 


(a)  Dyeing  with  a  mixture  of  two  or  more  diazotizable  dyes.     In 
carrying  out  this  method  care  should  be  taken  to  select  those  dyes  which 


316  DEVELOPED  DYES  ON  COTTON  AND  SILK 

require  similar  conditions  in  the  dyebath,  as  otherwise  great  waste  of  color 
may  ensue.  This  method  is  chiefly  used  for  the  dyeing  of  clarets,  browns, 
and,  blacks. 

ip)  Using  a  mixture  of  developers.  In  this  case  it  is,  of  course,  neces- 
sary to  use  either  alkaline  or  acid  developers  e^iclusively,  or  to  employ 
those  that,  even  if  not  of  the  same  class,  may  yet  work  together.  The 
shades  produced  in  this  case  are  usually  intermediate  to  those  which  would 
be  obtained  by  the  developers  if  used  singly. 

(c)  The  use  of  an  amino  developer,  and  subsequent  rediazotization  of 
the  color  and  development  of  the  color  anew^  This  method  is  not  much 
employed,  as  it  requires  such  a  number  of  processes  and  the  duplication  of 
the  color  in  succeeding  lots  is  very  difficult.  It  is  only  suitable  for  the  dye- 
ing of  certain  browns, 

(f?^  Dyeing  simultaneously  with  a  mixture  of  diazotizable  and  non- 
diazotizable  dyes.  This  is  the  most  important  method  for  producing 
radical  modifications  of  shade  and  is  the  one  which  is  chiefly  used  in 
practice.  Only  those  dyes  which  are  unaffected  by  the  process  and 
which  at  the  same  time  are  fast  to  washing  and  acids  should  be 
used. , 

{kj)  Topping  the  developed  dyes  with  basic  colors.  The  developed 
dyes  act  as  mordants  for  the  basic  colors  in  the  same  manner  as  the  sub- 
stantive dyes.  This  process  is  very  useful  in  enabling  exact  matching 
of  colors  and  also  for  the  purpose  of  adding, brilliancy  of  tone  to  the  devel- 
oped dyes,  which  otherwise  are  rather  dull. 

4.  Application  of  Developed  Dyes  to  Silk. — The  process  of  diazotizing 
and  developing  certain  of  the  substantive  colors  on  the  fiber  may  be  applied 
to  silk  with  very  good  results.  The  colors  so  obtained  have  excellent 
fastness  to  water  and  boiling  soap,*  and  some  of  the  dyes  have  even  good 
fastness  to  milling.  Where  colors  requiring  these  qualities  are  needed  on 
silk  this  process  of  dyeing  is  quite  largely  used.  This  is  especially  true 
where  a  fulling  fast  black  is  desired  on  silk  noils  to  be  used  for  fancy  effects 
in  woolen  fabrics.  The  method  of  applying  these  djxs  to  silk  is  prac- 
tically the  same  as  that  used  in  diving  cotton.  The  substantive  dye  is 
first  applied  in  a  bath  containing  boiled-off  liquor  or  soap  with  the  addi- 
tion of  10  to  40  per  cent  of  glaubersalt  (depending  on  the  depth  of  the  shade). 
The  silk  is  entered  lukewarm  and  the  bath  is  gradually  brought  to  the  boil 
and  dyed  just  under  the  boil  for  one-half  hour.  In  some  cases  it  may  be 
necessary  to  acidify  the  bath  with  acetic  or  sulphuric  acid  in  order  to 

*  Colors  on  raw  silk  which  will  subsequently  withstand  a  degumming  operation  in  a 
boiling  soap  bath  maj'  be  obtained  with  Primuline  developed  with  beta-naphthol  and 
with  Diamine  Fast  Yellow  A  coupled  with  diazotized  paranitraniline.  Other  colors 
which  will  also  stand  this  process  are  Victoria  Blue  B,  Forniyl  Violet  S4B  after-treated 
with  tannin  and  antimony,  as  well  as  most  of  the  alizarine  dyes  on  a  chrome  mordant. 


D^'ES  SUITABLE   FOR  SILK  317 

obtain  proper  exhaustion  of  the  color.  After  dyeing  the  goods  are  rinsed  and 
diazotized  in  a  cold  bath  containing  4  per  cent  of  sodium  nitrite  and  6  per 
cent  of  sulphuric  acid,  rinsed,  and  then  developed  immediately  as  required. 
About  the  only  developers  used  in  connection  with  silk  dj^eing  are  pheny- 
lene-diamine  salt  (use  0.7  per  cent  dissolved  in  one-third  its  weight  of  soda) 
and  beta-naphthol  (use  1  per  cent  dissolved  in  its  own  weight  of  caustic 
soda  lye  of  77°  Tw.).  The  developing  bath  is  used  cold  for  fifteen  minutes, 
then  rinse  well  and  wash  in  a  hot  soap  solution ;  finally  brighten  by  passing 
through  weak  acetic  acid  and  dry  without  rinsing.  Primuline  Red  and 
Diazo  Black  are  the  two  principal  developed  colors  used  for  silk.* 

The  following  list  gives  the  substantive  dj'^s  which  may  be  applied  to 
silk  by  the  method  of  diazotizing  and  developing  the  color  on  the  fiber. 

Benzo  Fast  Black  (beta-naphthol)  Diazo  Bordeaux  (beta-naphthol) 

Benzo  Nitrol  Browns  (diazotized  paranitran-  Diazo  Brilliant  Black  B  (naphthol  S) 

iline)  Diazo  Brown  G  (beta-naphthol,  also  with 
Columbia  Brown  R  (toluylene-diamine)  soda) 

Diamine  Azo  Blue  R  (beta-naphthol)  Diazo  Indigo  Blue  B,  M  (beta-naphthol) 

Diamine  Azo  Scarlet  B,  R  (beta-naphthol)  Diazo  Red  Blue  3R  (beta-naphthol) 

Diamine  Black  BH   (beta-naphthol,  pheny-  Direct   Deep   Black  E,  RW  (beta-naph- 

lene-diamine)  thol) 

Diamine  Nitrazol  Browns  (diazotized  para-  Naphtogene  Blue  2R  (beta-naphthol) 

nitraniline)  Pluto  Orange  G  (diazotized  paranitrani- 
Diaminogene  B   (beta-naphthol,  phenylene-         line) 

diamine)  Primuline   (beta-naphthol) 

Diaminogene  Blues  (beta-naphthol)  Zambesi  Black  D,  F,  R  (toluylene-dia- 
Diaminogene  Sky  Blue  N  (beta-naphthol)  mine) 

Diazethyl  Black  (naphthol  S)  Zambesi  Brown  G  (toluylene-diamine) 

Diazo  Black  2B  (beta-naphthol)  Zambesi  Indigo  Blue  2R  (beta-naphthol) 

Diazo  Blue  3R  (beta-naphthol)  Zambesi  Pure  Blue  4B  (beta-naphthol) 

'^.  Coupled  Dyes. — This  class  of  colors,  though  of  minor  importance, 
has  some  use  for  the  production  of  fast  brown  shades  on  cotton.  Like 
the  developed  colors,  they  are  also  built  up  by  chemical  means  in  the  fiber 
itself,  but  instead  of  the  dyestuff  which  is  dyed  on  the  cotton  being  diazo-w 
tized,  the  operation  is  reversed,  and  the  dyestuff  is  used  as  a  developer  to 
combine  (or  couple)  with  a  diazotized  base,t  which  latter  consists  almost 

*  The  coupling  process  of  treating  the  dyed  color  with  diazotized  paranitraniline 
may  also  be  used  in  the  dyeing  of  silk  for  the  production  of  certain  fast  shades.  The 
method  is  carried  out  in  the  same  manner  as  for  cotton. 

t  The  building  up  of  dyestuffs  directly  on  the  fiber  may  take  place  in  three  different 
ways : 

(a)  Dyeing  with  certain  substantive  colors,  then  diazotizing  and  finally  developing 
with  a  phenolic  or  amino  body.     This  is  the  process  which  has  just  been  considered. 

(b)  Dyeing  with  certain  substantive  colors,  then  developing  with  a  solution  of 
diazotized  paranitraniline.     This  includes  the  group  of  coupled  dyeings. 

(c)  Padding  the  cotton  with  a  phenolic  body  (such  as  beta-naphthol),  then  develop- 


318 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


exclusively  of  paranitraniline,  C6H4(N02)- (NH2).  The  process  consists 
brief!}'  of  dyeing  the  cotton  with  a  suitable  substantive  dyestuff  in  the 
usual  manner,  then  coupling  in  a  fresh  cold  bath  containing  a  solution 
of  diazotized  paranitraniline,  soda  ash,  and  sodium  acetate.  The  solu- 
tion of  diazotized  paranitraniline  is  prepared  as  follows:  2  lbs.  of  parani- 
tranihne  are  dissolved  in  1|  gallons  of  pure  boiling  water,  adding  |  gallon 
of  hydrochloric  acid  (32°  Tw.)  and  stirring  until  the  solution  is  complete. 
Then  add  3|  gallons  of  cold  water,  which  will  precipitate  paranitraniline 
hydrochloride  in  the  form  of  a  yellow  paste.  When  this  is  cold  a  solution 
of  1|  lbs.  of  sodium  nitrite  in  1  gallon  of  cold  water  is  added.  In  about 
fifteen  to  twenty  minutes  a  clear  solution  should  result;  this  is  diluted  to 

20  gallons  with  cold  water.  The 
solution  thus  prepared  consists  of 
the  diazo  body  of  paranitraniline, 
C6H4(N02)-N  :  N-Cl,  and  is  a 
quite  unstable  substance.  On  this 
account  the  solution  should  be 
prepared  just  before  being  needed, 
and  should  not  be  kept  for  any 
great  length  of  time.  If  preserved 
from  direct  light  and  heat  in  wooden 
or  earthen  vessels,  it  will  keep  its 
strength  for  several  days.  The 
coupling  bath  for  100  lbs.  of  cotton 
for  light  shades  (1§  to  2  per  cent 
dyeings)  is  prepared  with  3|  gallons 
of  the  diazotized  paranitraniline 
solution,  8  ozs.  of  soda  ash,  and  3j  ozs.  of  sodium   acetate.     For  heavy 

ing  with  a  diazotized  amino  base.  This  includes  the  group  of  naphthol  colors,  of  which 
Paranitraniline  Red  is  the  tjTie  and  chief  representative. 

All  three  of  these  methods  are  the  same  in  principle,  and  include  the  same  three 
essentials : 

(a)  An  aromatic  amino  base. 

(6)  A  diazotizing  process  whereby  this  base  is  converted  into  a  diazo  salt. 

(c)  A  phenolic  or  amino  body  capable  of  combining  with  the  diazo  salt  to  yield  a 
stable  dyestuff. 

The  first  method  differs  from  the  other  two  in  the  order  in  which  these  three  essen- 
tials are  applied  to  the  cotton  fiber.  The  first  two  methods  start  with  a  body  which 
already  possesses  the  properties  of  a  substantive  dyestuff,  while  in  the  third  method  no 
actual  dyestuff  at  all  is  employed,  but  the  coloring  matter  is  formed  from  its  constitu- 
ents. In  the  first  method  the  substantive  dye  used  furnishes  the  base  of  the  diazo  body; 
whereas  in  the  second  method  the  dyestuff  plays  the  role  of  the  developer  with  which 
the  diazo  salt  is  to  be  combined.  In  the  third  method  only  phenolic  bodies  are 
employed  for  coupling  with  the  diazo  salt  of  the  base,  though  the  number  of  bases 
with  which  the  diazo  salts  may  be  used  is  quite  large. 


Fig.  169. — Apparatus  for  Impregnating 
Yarn  with  Beta-Naphthol. 


COUPLING   PROCESS  OF   DYEING  319 

shades  (3  to  4  per  cent  dyeings)  these  quantities  are  increased  to  5  to 
7  gallons  of  diazotized  paranitraniline  solution,  1  lb.  of  soda  ash,  and 
6  ozs.  sodium  acetate.  The  dyeings  obtained  by  this  process  have 
very  good  fastness  to  washing,  fulling,  and  acids.  The  colors  may 
be  shaded  by  the  addition  of  small  quantities  of  basic  dyes  to  the 
coupling  bath.  Attempts  have  been  made  to  prepare  the  diazotized 
paranitraniline  in  such  a  form  that  it  will  be  stable  enough  to  become 
an  article  of  trade.  One  such  preparation  was  Nitrazol  C,  but, 
owing  to  the  liability  of  this  substance  to  spontaneous  combustion,  it  is  no 
longer  handled.  Nitrosamine  Red,  Benzo  Nitrol  and  Azophor  Red  PN 
are  somewhat  similar  products. 

Azophor  Red  PN  is  a  form  of  diazotized  paranitraniline,*  and  is  sold  as 
a  brownish  yellow  powder.  The  padding  with  naphthol  is  done  in  pre- 
cisely the  same  manner  as  when  employing  paranitraniline,  but  the  devel- 
oping bath  is  prepared  in  a  somewhat  different  manner,  f 

*  Azophor  Red  PN  is  diazotized  paranitraniline  with  an  admixture  of  aluminium 
sulphate  and  sodium  sulphate.  Nitrazol  C  is  paranitranihne  diazotized  in  a  solution  of 
strong  sulphuric  acid  and  mixed  with  sufficient  sodium  sulphate  to  produce  a  stable  solid 
mass.  Nitrosamine  Red  is  the  sodium  salt  of  para-nitro-phenyl-nitrosamine  produced 
by  the  action  of  caustic  soda  on  para-nitro-diazobenzene  chloride.  As  such  it  does  not 
react  with  the  alkaline  solution  of  beta-naphthol,  but  is  readily  reconverted  into  the  diazo 
compound  by  the  action  of  acid,  and  consequently  it  may  be  used  in  acid  solution  like 
the  ordinary  diazo  compound. 

Paranitraniline  S  is  the  crystallized  sulphuric  acid  salt  of  paranitraniline.  It  occurs 
in  the  form  of  a  dull  yellowish  crystalline  powder.  When  treated  with  water  it  turns 
to  a  deep  yellowish  color,  decomposing  into  free  sulphuric  acid  and  paranitraniline; 
hence  it  can  only  be  dissolved  in  hot  water  containing  acids.  It  is  used  in  practically 
the  same  way  as  paranitraniline  but  only  requires  one-half  the  quantity  of  sodium 
nitrite  for  diazotization,  as  it  contains  one-half  the  amount  of  actual  paranitrani- 
line. 

t  The  manufacturers  recommend  the  following  process:  50  lbs.  of  Azophor  Red 
PN  are  dissolved  by  stirring  in  40  gallons  of  cold  water;  this  requires  from  fifteen  to 
twenty  minutes,  after  which  the  solution  is  allowed  to  stand  for  one  to  two  hours,  and 
then  strained  through  a  cotton  cloth  to  remove  a  small  amount  of  insoluble  matter  which 
rises  to  the  surface.  The  clear  solution  thus  obtained,  which  contains  a  salt  of  para- 
nitro-diazo-benzene,  is  neutralized  by  the  addition  of  26.8  lbs.  of  caustic  soda  (36°  Tw.), 
diluted  to  10  gallons,  stirring  fifteen  minutes,  or  until  the  precipitate  which  it  produces 
redissolves;  the  whole  developing  solution  is  then  diluted  with  its  own  volume  of  water, 
or  50  gallons.  The  developing  bath  must  be  used  directly  after  neutralizing  with  soda, 
but  the  acid  solution  obtained  by  dissolving  the  Azophor  Red  PN  is  fairly  stable,  and  if 
kept  in  a  cool  place  and  not  exposed  to  a  strong  light,  may  be  kept  for  several  days. 
After  passing  through  the  bath  the  cotton  is  allowed  to  stand  for  a  short  time  to  insure 
complete  development,  after  which  it  is  washed  and  soaped  for  fifteen  minutes  at  140° 
F.  in  a  solution  containing  1  gram  of  soap  per  liter.  By  the  use  of  Naphthol  R  in  the 
padding  solution  instead  of  the  ordinary  beta-naphthol,  somewhat  bluer  reds  are 
obtained.  It  is  also  considered  that  the  addition  of  Para  Soap  PN  (ricinoleate  of 
ammonia)  instead  of  Turkey-red  oil  to  the  bath  increases  the  brilliancy  of  the  color. 


320 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


Nitrosamine  Red  has  the  probable  constitution  of  C6H4<;^     \Na 

It  is  quite  stable,  and  on  treatment  with  hydrochloric  acid  jnelds  para- 
nitro-diazo-benzene  chloride;  that  is,  diazotized  paranitraniline,  according 
to  the  following  reaction  :* 

C6lU<{    ^^^  +2HC1  =  CgH4<^^      ^         +H20+NaCl. 


Fig.  170. — Wringer  for  Naphthol  Prepared  Yarn. 


6/  The  Naphthol  Colors. — This  class  includes  such  colors  as  Para- 
nitraniline Red,  Dianisidine  Blue,  etc.f  Tli£y  are  azo  dyes  built  up  on 
the  fiber  by  first  treating  with  a  developer  (usually  beta-naphthol)  and 
then  with  a  diazotized  solution  of  a  suitable  base,  such  as  paranitraniline. 
The  process  is  practically  the  reverse  of  the  ordinary  method  for  the  pro- 
duction of  diazotized  and  developed  colors,  and  is  more  analogous  to  the 

*  The  preparation  of  the  developing  solution  consists  in  treating  the  Nitrosamine  Red 
with  acid;  87.5  lbs.  of  Nitrosamine  Red  paste  are  mi.xed  with  75  gallons  of  water  and 
37.5  lbs.  of  hydrochloric  acid  (30°  Tw.).  Stir  well  for  ten  to  fifteen  minutes,  then  add 
44  lbs.  of  acetate  of  soda  crystals.  Stir  tUl  dissolved,  strain  through  cloth,  and  dilute 
to  100  gallons.  It  is  possible  to  dye  with  Nitrosamine  Red  and  beta-naphthol  in  one 
bath,  but  the  colors  produced  are  inferior  to  those  obtained  by  padding  previously  with 
the  naphthol  solution.     The  process  is  as  follows: 

Single-bath  Nitrosa7nine  Red. — Dissolve  by  stirring  3  lbs.  2  ozs.  of  powdered  beta- 
naphthol,  2  lbs.  13  ozs.  caustic  soda  (70°  Tw.)  17  lbs.  of  Nitrosamine  Red  (25  per 
cent)  in  20  gallons  of  water.  Then  add  10  Ib.s.  of  Turkey-red  oil.  Pad  the  cloth  in  this 
solution,  dry  at  a  low  temperature,  and  allow  to  lie  twelve  hours  to  develop.  At  the 
end  of  this  time  the  cloth  will  have  acquired  a  dull  orange  color,  and  is  then  washed 
and  soaped  to  clear  the  color. 

t  Probably  the  first  commercial  application  of  the  naphthol  colors  was  in  England  in 
1880  by  HoUiday,  who  dyed  yarn  a  fine  bluish  red  for  towel  headings  under  the  name  of 
Vacanceine  Red.  It  was  produced  bj'  padding  the  yarn  with  beta-naphthol  and  coup- 
ling with  diazotized  beta-naphthylamine.  Para  Red  was  first  produced  in  1SS9  and 
was  developed  by  the  Farbwerke  Hochst.  It  rapidly  became  a  cheap  substitute  for 
Turkey  Red  on  piece-goods  but  was  not  employed  to  anj'  great  extent  in  yarn  dyeing. 
It  was  very  largely  introduced  as  a  printing  color  in  Russia. 


NAPHTHOL  COLORS 


321 


process  used  in  the  dyeing  of  the  coupled  colors,  except  that  instead  of 
starting  with  a  dyestiiflf  in  the  first  place,  a  simple  developer  without  spe- 


cial tinctorial  properties  is  used. 


in  cot^h'  printing  t?' 


The  naphthol  colors^  are -^nore  employe 

dy^iag^in^  the  latter  Paranitraniline  Red  is  about  the  only  color  of  this 
(fl^filass-Avhieh  has  any  pYHctiQsd^Jipovlsi^^f'^i'J  r^^^t^ J^'c^^ 
'^        The  principal  developers  used  in  this  process  are  the  following:   beta 

naphthol  (and  its  related  products  such  as  Naphthol  R  *  and  D),  alpha 


Fig.  171. — Developing  Para  Red  on  Piece-Goods.     (Cassella.) 


naphthol  and  resorcine.     The  principal  bases  which  may  be  used,  and  the 
colors  they  produce  in  combination  with  beta-naphthol,  are  as  follows: 


Ba&e. 
Alpha-naphthylamine 
Amino-azo-benzene 
Aniline 

Azo-black  base 
Benzidine 

Beta-naphthylamine 
Chloranisidine 
Dianisidine 
Meta-nitraniline 
Nitro-ortho-toluidine 
Nitro-para-toluidine 
Nitro-phenetidine 
Ortho-amino-azo-toluene 
Para-nitraniline 
Para-toluidine 
Tolidine 


Color  with  beta-naphthol. 
bluish  red 
crimson 
orange  yellow 
black 

purplish  brown 
crimson 
scarlet 
blue 
orange 
orange  red 
orange 

bluish  crimson 
claret  red 
red 

yellow  orange 
purplish  brown 


*  This  is  the  (2  :  7)  beta-naphthol-mono-sulphonic  acid  F,  and  is  also  known  as 
shading  salt.  It  gives  a  bluer  tone  to  the  red.  Naphthol  D  is  a  mixture  of  beta- 
naphthol  with  dioxy-naphthalene. 


322  DEVELOPED  DYES  ON  COTTON  AND  SILK 

The  general  process  of  dyeing  with  the  naphthol  colors  is  first  to 
impregnate  the  cotton  with  a  solution  containing  the  beta-naphthol  and 
soluble  oil;  the  preparation  of  the  solution  of  the  diazotized  base;  and 
the  development  of  the  color  in  the  diazo  solution. 

The  fastness  of  the  naphthol  colors  is  in  general  very  good,  in  fact  sur- 
passing most  of  the  cotton  dyes  in  this  respect  with  the  exception  of  the  vat 
dyes.*  Most  of  the  colors  are  very  fast  to  soaping  and  washing  and  light, 
and  many  also  possess  good  fastness  to  bleaching  with  chlorine.  These 
colors  have,  however,  certain  defects:  (a)  they  are  liable  to  crock  to  a  con- 
siderable degree,  especially  if  not  very  carefully  dyed,  and  this  would  be 
expected  owing  to  the  pigment  character  of  the  dyestuff  formed  in  and  on 
the  fiber;  (5)  they  sublime  from  the  fiber  when  heated. f 
^— ^.  Paranitraniline  Red. — This  is  much  used  in  place  of  Turkey  Red.  It 
furnishes  a  very  fine  bright  shade  of  red,  somewhat  more  yellow  in  tone, 
however,  than  Turkey  Red.  The  shade  may  be  made  bluer  in  tone  by 
proper  treatment. J  The  color  is  very  fast  to  washing  and  fulling,  not 
bleeding  into  interwoven  white  when  scoured  in  hot  soap  solutions.     It 

*  There  appeared  on  the  market  in  1914  a  new  developer  known  as  Naphthol  AS, 
consisting  of  beta-oxy-naphthoic  acid  anilide.  This  compound  aroused  considerable 
interest,  owing  to  the  great  brilliancy  and  fastness  of  the  colors  obtainable  from  it.  The 
blue  produced  by  coupling  it  with  dianisidine  in  the  presence  of  copper  chloride  is  said 
to  be  faster  to  chlorine  bleaching  than  either  Indigo  or  Hydron  Blue  and  the  red  obtained 
by  coupling  it  with  Fast  Red  G  base  is  said  to  be  faster  to  light  than  Para  ''Red.  A 
further  advantage  it  possesses  over  beta-naphthol  is  that  its  solution  appears  to  have 
substantive  dyeing  qualities  on  the  cotton  fiber,  and  hence  it  is  not  necessary'  to  dry 
the  naphthol-prepared  material,  but  after  well  squeezing  it  from  the  naphthol  bath  the 
goods  may  be  passed  directly  into  the  developing  bath.  It  is  used  as  follows:  12  parts 
Naphthol  AS,  20  parts  caustic  soda  (62°  Tw.)  and  30  parts  Turkey-red  oil.  The 
Naphthol  AS  is  stirred  into  a  smooth  paste  with  the  caustic  soda  and  the  oil,  then  add 
water  and  boil  until  dissolved  and  make  up  to  1000  partj,  then  add  12  parts  formalde- 
hyde (40  per  cent).  Impregnate  the  cotton  at  80  to  100°  F.  The  makers  of  this 
product  have  also  patented  a  process  whereby  the  Naphthol  AS  may  be  mixed  directly 
with  certain  nitrosamines  and  used  directly  under  the  name  of  "  Rapid  Fast  Dyes." 
The  concentrated  solutions  of  the  nitrosamines  are  mixed  with  the  Naphthol  AS  alkali 
salt  to  give  paste  or  powder  products  without  formation  of  the  color.  These  dissolve 
readily  in  cold  water  and  their  dilute  solutions  precipitate  the  respective  dyes  when 
warmed,  or  if  acetic  acid  and  chrome  are  added.  The  cloth  to  be  dyed  is  simply  padded 
with  the  mixed  "  Rapid  Fast  Dye,"  dried  in  a  hot  flue  and  passed  through  a  solution 
containing  acetic  acid  near  the  boil.  The  outbreak  of  the  war  prevented  further  devel- 
opment of  this  process. 

t  This  quality,  in  fact,  is  emploj^ed  as  a  characteristic  test  for  the  naphthol  dyes  on 
the  fiber,  the  sample  being  placed  between  white  cotton  cloth  and  ironed  with  a  hot  iron, 
when  the  color  will  sublime  onto  the  white  cloth.  Shades  that  have  been  coupled 
in  the  presence  of  a  copper  salt  (like  Dianisidine  Blue)  do  not  sublime. 

J  The  use  of  aluminate  of  soda  has  been  recommended  to  improve  the  bluish  tone  of 
Para  Red,  and  to  cause  the  beta-naphthol  to  be  better  fixed  during  the  drying.  It  is 
employed  as  an  addition  to  the  naphthol  preparation. 


PARANITRANILINE   RED 


323 


is  also  fast  to  perspiration  and  dilute  mineral  acids,  also  to  dilute  chloride 
of  lime  solution  for  mild  bleaching.  It  is  quite  fast  to  light,  though  it  is  not 
equal  in  this  respect  to  Turkey  Red.  x 

The  chief  difficulty  attached  to  the  dyeing  of  Paranitraniline  Red  is  in 
the  production  of  even  shades  which  are  well  penetrated  through  the 
fiber.  This  is  due  to  the  uneven  grounding  with  the  beta-naphthol  solu- 
tion, and  hence  the  solution  must  be  padded  on  mechanically  in  a  con- 
centrated form.  The  cotton  fiber  has  no  especial  attraction  towards  the 
beta-naphthol.  Caustic  soda  is  employed  in  this  solution  for  the  purpose 
of  more  thoroughly  dissolving  the  beta-naphthol,  which  is  not  soluble  in 
plain  water.  As  it  passes  into  solution  in  reality  it  becomes  converted 
into  the  sodium  salt  of  beta-naphthol.  Soluble  oil  or  Turkey-red  oil  is  also 
used  for  the  purpose  of  obtaining  better  penetration  and  a  more  even  dis- 
tribution of  the  beta-naphthol  solution  through  the  fiber.    Much  better 


Fig.  172.— Types  of  Padding  Machines  Showing  Methods  of  Running  Cloth. 

penetration  is  obtained  on  single-ply  yarns  than  on  tightly  twisted  yarns, 
and  the  yarn  should  also  be  especially  well  boiled-out  and  bleached  *  before 
attempting  to  pad  with  the  naphthol  solution.  It  is  much  easier  to  evenly 
pad  cloth  than  it  is  yarn,  as  the  mechanical  processes  are  much  simpler. 
After  the  cotton  is  padded  it  must  be  dried,  which  is  for  the  purpose  of 
making  the  beta-naphthol  more  insoluble,  so  that  it  will  not  be  redissolved 
from  the  fiber  when  passed  into  the  paranitraniline  solution.  The  inten- 
sity of  the  ultimate  color  obtained  depends  on  the  amount  of  the  beta- 
naphthol  deposited  in  the  fiber,  and  consequently  on  the  strength  of  the 
padding  solution.  If  heavier  or  more  bluish  shades  are  desired  an 
increased  amount  of  naphthol  and  caustic  soda  must  be  used;  also  by 
using  Naphthol  R  a  bluer  tone  may  be  obtained  more  closely  approaching 

*  In  order  to  brighten  or  clarify  the  shade  of  Paranitraniline  Red  on  unbleached  yarn, 
the  cotton  may  subsequently  be  chlored  in  a  solution  of  bleaching  powder  of  1°  Tw. 


324  DEVELOPED  DYES  ON  COTTON  AND  SILK 

that  of  Turkey  Red.  By  reducing  the  amount  of  oil  employed  the  ulti- 
mate color  obtained  will  be  yellower  in  shade.  In  employing  the  naphthol 
solution  it  is  expedient  to  use  it  warm  (120  to  140°  F.)  as  the  fiber  will  be 
better  penetrated.  The  naphthol  solution  should  be  freshly  prepared 
and  used  as  soon  as  possible,  as  it  commences  to  decompose  in  about  ten 
hours'  time.  It  should  be  kept  in  wooden,  enameled,  or  earthenware 
vessels,  and  neither  the  solution  nor  the  padded  yarn  or  cloth  should  come 
in  contact  with  metal,  especially  copper,  as  this  will  give  rise  to  brownish 
spots.* 

In  the  practical  operation  of  this  process  the  following  procedure  is 
recommended:  Take  1  Ib.f  of  yarn  on  a  stick  and  work  in  about  2  gallons 
of  the  naphthol  solution  in  a  wooden  vessel ;  give  four  to  five  turns,  wring, 
shake  out  the  skein,  then  wring  again  and  lay  the  yarn  aside.  Add 
to  the  bath  about  |  pint  of  the  naphthol  solution,  take  a  second  pound-lot 
of  the  yarn  and  proceed  as  before.  In  wringing  the  yarn  the  excess  of 
liquor  is  run  back  into  the  bath  each  time.  The  entire  series  of  opera- 
tions of  steeping  and  wringing  is  now  repeated  taking  the  lots  of  j^arn 
in  the  same  succession  as  before,  but  no  further  additions  of  the  naphthol 
solution  are  made. 

The  use  of  special  yarn  padding  or  impregnating  machines  has  been 
introduced  in  this  method  of  dyeing,  but  the  secret  of  obtaining  successful 
results  is  in  the  even  distribution  of  the  naphthol  solution,  and  it  is  claimed 
that  this  can  be  done  better  by  hand  treatment  than  by  any  other  means, 

*  By  the  action  of  copper  salts  Paranitraniline  Red  is  easily  converted  into  a  brown, 
and  this  fact  is  turned  to  practical  account  for  the  production  of  brown  shades.  The 
copper  salt  may  be  applied  either  along  with  the  naphthol  or  with  the  developer,  or  the 
developed  color  may  be  subsequently  treated  with  the  copper  salt.  The  most  satisfactory 
results,  however,  are.  obtained  by  adding  the  copper  salt  to  the  padding  solution,  because 
the  presence  of  the  metallic  salt  renders  the  diazo  solution  very  unstable.  This,  of 
course  necessitates,  the  preparation  of  an  alkaline  copper  solution,  and  is  done  as 
follows:  350  grams  of  copper  chloride  (76°  Tw.),  125  grams  of  tartaric  acid,  100  grams  of 
glycerin,  and  425  grams  of  caustic  soda  (36°  Tw.).  Dissolve  the  tartaric  acid  in  the 
copper  solution,  add  the  glycerin,  and  then  run  in  the  alkali  gradually,  stirring  until  the 
precipitate  which  at  first  forms  redissolves.  The  naphthol  preparation  is  made  with  25 
grams  of  beta-naphthol,  59  grams  of  caustic  soda  (36°  Tw.),  30  grams  of  Turkey-red 
oil  (or  Para  Soap  PN),  and  100  grams  of  the  alkaline  copper  solution.  Dilute  to  1  liter, 
and  pad  in  the  usual  manner,  dry  at  a  low  temperature  and  develop  as  for  red;  the  most 
suitable  bases  being  para-nitraniline,  meta-nitraniline,  and  beta-naphthylamine. 

t  In  order  that  the  quantity  of  naphthol  solution  retained  by  the  yarn  may  be  made 
as  uniform  as  possible,  it  is  recommended  to  weigh  the  yarn.  For  well-bleached  yarn, 
the  following  proportionate  weights  may  be  taken  as  equivalent. 

100  lbs.  raw  cotton  yarn  give 
88  lbs.  dry  bleached  yarn,  or 

152-158  lbs.  hydro-extracted  wetted  yarn. 
When  properly  padded  with  the  beta-naphthol  solution  the  same  yarn  should  weigh 
hydro-extracted  about  162-176  lbs.,  or  dry  about  97  lbs. 


PREPARING   WITH  NAPHTHOL  325 

though,  of  course,  it  requires  a  highly  skilled  operator  to  carry  out  the 
processes  successfully'',  as  all  the  operations  have  to  be  conducted  with  the 
greatest  exactness. 

After  all  the  yarn  has  been  padded,  it  is  hydro-extracted  and  hung 
up  to  dry.  If  the  wringing  or  hydro-extracting  is  incomplete  so  that  an 
excess  of  the  naphthol  solution  is  left  in  the  fiber,  brown  streaks  are  liable 
to  form. 

For  100  lbs.  of  yarn  the  naphthol  solution  is  prepared  as  follows: 

3  lbs.  of  beta-naphthol ; 
3  lbs.  of  caustic  soda  solution  (72°  Tw.); 
10  lbs.  of  Turkey-red  oil,  and  dilute  with  water  to  7  J  gallons. 

The  time  allowed  for  drying  the  yarn  after  padding  should  be  about 
three  hours,  and  the  best  temperature  for  drying  is  about  140°  F.*  To 
obtain  good  results  it  is  absolutely  necessary  that  the  evaporated  moisture 
be  carried  off  by  a  flue  or  fan  and  also  that  the  yarn  should  be  turned 
several  times  during  the  drying,  but  without  being  touched  by  the  hands,  t 
This  is  to  prevent  an  excess  of  the  padding  solution  from  accumulating  in 
the  lower  parts  of  the  hanks.  The  skeins  should  be  hung  up  loosely 
and  not  overlap.  Care  must  be  taken  in  the  drying  not  to  have  the  yarn 
acquire  a  brownish  color,  J  as  this  will  considerably  dull  the  eventual 
red  color  produced. 

The  paranitraniline  bath  should  not  have  a  temperature  above  65°  F., 
otherwise  the  color  will  not  be  properly  developed  and  the  shades  will 
come  out  yellow  and  streaky. §     The  diazotized  paranitraniline  solution 

*  If  dried  at  high  temperatures  the  beta-naphthol  will  volatilize  from  the  fiber. 

t  In  the  drying  of  yarn  grounded  with  beta-naphthol,  the  sticks  on  which  the  hanks 
are  hung  should  be  previously  rubbed  with  some  of  the  naphthol  solution;  and  care 
should  be  taken  to  prevent  any  water  dropping  on  the  yarn  during  the  drying,  or  a 
spot  will  be  produced. 

t  In  order  to  prevent  the  material  from  turning  brown  it  has  been  recommended  to 
add  to  the  naphthol  solution  a  solution  of  antimony  oxide  in  caustic  soda  and  glycerin. 
Tartar  emetic  (or  other  antimony  salt),  together  with  an  equal  weight  of  glycerin,  is 
dissolved  in  water,  and  a  solution  of  caustic  soda  is  added  until  the  precipitate  at  first 
formed  is  redissolved.  The  antimony  salt  should  be  used  in  the  proportion  of  about 
25  per  cent  of  the  naphthol.  Ready  prepared  products  of  this  nature  are  on  the  market, 
such  as  Naphthol  LC.  Owing  to  the  e.xpense  of  the  antimony  this  process  is  rarely 
used.  It  is  also  claimed  that  the  addition  of  glucose  for  the  same  purpose  acts  almost 
as  well. 

§  Diazo  compounds  are  notably  very  unstable  products,  and  are  not  prepared  in 
the  solid  state  for  dyeing.  Even  in  solution  they  gradually  decompose,  particularly 
when  heated,  and  in  decomposing  they  form  resinous  products  from  which  good 
colors  cannot  be  obtained.  It  is  necessary,  therefore,  to  keep  the  temperature  low,  if 
possible,  below  40°  F.  This  is  true  of  all  diazo  solutions,  whether  used  for  naphthol  dyes 
or  for  other  classes  of  developed  dyes.  As  ice  is  frequently  added  to  keep  the  tempera- 
ture down,  all  these  classes  of  dyes  are  sometimes  spoken  of  as  "ice  colors."  The  diazo 
compounds  also  decompose  rapidly  in  alkaline  solution,  hence  it  is  essential  to  use  a 


326 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


under  normal  conditions  will  keep  for  several  days,  but  after  the  addition 
of  the  acetate  of  soda  it  will  not  keep  more  than  eight  to  ten  hours.  Copper 
or  metal  vessels  should  not  be  used  for  this  solution.  In  the  practical 
working  of  the  process  it  is  recommended  to  operate  in  the  same  manner 
as  for  the  grounding  with  naphthol ;  that  is,  to  use  only  a  pound  of  the  yarn 
at  a  time  for  treatment.  This  will  require  about  1|  gallons  of  the  parani- 
traniline  solution  and  the  same  quantity  of  cold  water.  Give  the  yarn  a 
few  turns  in  this  solution,  wring  slightly,  give  a  few  more  turns,  and  finally 
wring  well,  allowing  the  excess  of  liquor  to  run  back  into  the  bath.     For 


Fig.  173. — Vacuum  Hydro-Extractor  for  Cloth. 

100  lbs.  of  yarn  about  16  gallons  of  the  paranitraniline  liquor  will  be 
required. 

After  the  yarn  has  been  dyed  it  is  important  that  it  should  be  rinsed  as 
soon  as  possible,  each  hank  being  rinsed  as  soon  as  dyed. 

The  diazotized  paranitraniline  solution  is  prepared  as  follows:  2  lbs.  of 
paranitraniline  are  stirred  to  a  homogeneous  paste  in  an  enameled  or 
wooden  vessel  with  3  gallons  of  boiling  water.  Then  add  5|  lbs.  of  hydro- 
chloric acid  (32°  Tw.),  continue  stirring  for  fifteen  minutes,  and  boil  until 
the  solution  is  clear,  which  is  an  important  point;  then  add  10  gallons  of 
cold    water.     The  object   of  this  is  to   precipitate   the  paranitraniline 

rather  strongly  acid  solution.  But  as  the  diazo  compound  does  not  combine  with  the 
naphthol  in  the  presence  of  strong  mineral  acids,  sufficient  sodium  acetate  is  added  to 
the  diazo  solution  to  neutralize  the  free  mineral  acid. 


PREPARATION   OF   DIAZO  SOLUTION  '627 

hydrochloride  in  a  very  fine  state  of  division,  so  it  easily  diazotizes.  To 
this  mixture  then  add  a  solution  of  1  lb.  of  sodium  nitrite  in  2  gallons 
of  cold  water.  Run  this  solution  in  quickly  and  stir  for  fifteen  minutes.* 
The  solution  should  contain  a  sHght  excess  of  nitrous  acid,t  and  should 
therefore  develop  a  blue  color  with  starch-iodide  paper.  Dilute  to  20  gal- 
lons and  this  will  form  the  stock  diazo  solution  from  which  the  developing 
bath  is  prepared  as  required  by  diluting  with  six  times  its  volume  of 
water  and  neutralizing  with  sodium  acetate.  J 

*  In  case  the  diazo  solution  does  not  become  clear  on  adding  the  nitrite  solution,  but 
forms  a  copious  yellow  precipitate,  it  indicates  a  lack  of  hydrochloric  acid  or  sodium 
nitrite.  In  the  diazo  solution  hydrochloric  acid  must  always  be  in  excess  to  make  the 
solution  more  stable,  and  excess  of  nitrite  is  necersary  to  make  up  for  loss  of  nitrous 
fumes  and  to  make  it  certain  that  all  of  the  paramtraniline  has  been  diazotized,  for  if 
this  is  not  the  case  the  unchanged  paranitraniline  will  couple  with  the  diazotized  para- 
nitraniline  to  form  the  yellow  precipitate  referred  to. 

t  Copious  evolution  of  nitrous  fumes,  however,  must  be  avoided,  as  this  is  an  indi- 
cation of  improper  conditions ;  the  large  excess  of  nitrous  acid  will  form  nitrosonaphthol, 
which  wUl  diminish  the  stability  of  the  diazo  solution  and  tend  to  dull  the  color. 

t  Though  the  dia«otization  of  paranitraniline  by  m  cans  of  sodium  nitrite  and  hydro- 
chloric acid  is  rather  simple  as  a  chemical  reaction,  yet  it  requires  considerable  practice 
in  order  to  obtain  a  perfectly  soluble  diazo-compound.  In  this  connection,  the  following 
precautions  have  been  recommended: 

(1)  The  paranitraniline  should  first  be  stirred  up  with  sufficient  acid,  allowed  to  stand 
for  a  few  minutes,  and  then  gradually  brought  into  solution  with  hot  or  boiling  water. 

(2)  The  clear,  hot  solution  should  then  be  poured  in  a  thin  stream  into  cold  water, 
while  a  constant  stirring  is  maintained,  in  order  that  the  precipitate  which  forms  may  be 
as  finely  divided  as  possible,  because  the  finer  and  more  uniform  this  precipitate,  the 
quicker  and  more  complete  will  be  the  action  of  the  sodium  nitrite. 

(3)  The  lower  the  temperature  is  maintained  while  adding  the  sodium  nitrite,  the 
clearer  and  more  stable  will  be  the  diazo  solution.  The  addition  of  ice,  however,  is  neces- 
sary only  on  hot  days;  as  a  rule,  cold  water  alone  is  sufficient,  it  only  being  necessary 
not  to  allow  the  temperature  to  rise  above  50°  F. 

(4)  The  solution  of  sodium  nitrite  should  be  concentrated,  and  should  be  run  in 
quickly  and  with  constant  stirring;  the  more  rapidly  the  sodium  nitrite  is  added  the 
clearer  will  be  the  diazo  solution.  The  diazotization  of  the  paranitraniline  is  complete 
only  after  all  of  the  nitrite  has  been  added,  and  the  solution  has  been  allowed  to  stand 
ten  to  fifteen  minutes.  It  may  be  ascertained  if  free  nitrous  acid  is  still  present  in  the 
bath  by  testing  with  a  strip  of  potassium  iodide  starch  paper  which  would  turn  bluish 
black  in  color.  When  all  of  the  diazo  solution  is  not  to  be  used  immediately  but  in 
successive  quantities,  only  those  portions  in  actual  use  should  be  neutralized  with  sodium 
acetate,  as  after  the  addition  of  this  salt  the  solution  is  far  less  stable  than  in  the  acid 
condition. 

(5)  The  hydrochloric  acid  solution  of  the  diazo-body  is  unsuitable  for  developing, 
because  under  these  conditions  the  beta-naphthol  does  not  cause  any  formation  of 
dyestuff.  The  development  only  takes  place  in  acetic  acid  or  neutral  solution;  and 
excess  of  acetic  acid  does  not  matter,  but  the  slightest  quantity  of  free  hj'drochloric 
acid  will  considerably  affect  the  results.  When  a  mixture  of  soda  ash  and  sodium  ace- 
tate is  used  for  neutralizing,  their  relative  quantities  should  be  so  adjusted  as  to  leave 
the  solution  slightly  acid;  if  sufficient  soda  ash  is  used  to  cause  the  diazo  solution  to  be 
neutral  or  alkaline  in  a  short  time  it  becomes  cloudy  and  the  developed  shades  are  poor. 


328 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


The  dyed  3'arn  is  then  put 
through  a  final  process  of  "  bright- 
ening," which  is  done  by  working 
the  yarn  for  a  short  time  at  140°  F. 
in  a  solution  of  4  grams  of  soap  per 
liter.  A  good  olive  oil  soap  should 
be  used,  otherwise  j^ellower  toned 
shades  may  be  produced.  Bluer 
but  not  so  bright  shades  may  be 
obtained  b}'  passing  the  cotton 
through  a  further  bath  containing 
18  parts  of  Turkey-red  oil  and  2 
parts  of  soda  ash  per  1000  parts  of 
water. 

In  order  to  obtain  clear  bright 
shades  in  the  dyeing  of  Paranitra- 
niline  Red  it  is  necessary  that  all 
of  the  chemicals  employed  should 
be  as  pure  as  possible.  Caustic 
soda  lye  of  a  brownish  color  and 
containing  iron  in  solution  should 
not  be  used.  It  should  also  be 
borne  in  mind  that  the  caustic 
soda  Ij'e  decreases  in  strength  when 
left  exposed  to  the  aii-,  as  it  rapidly 
absorbs  carbonic  acid  and  a  portion 
becomes  converted  into  sodium 
carbonate.*  On  this  account  the 
naphthol  padding  solution  soon  de- 
teriorates. The  Turkey-red  oil 
used  should  be  neutral  and  not  acid, 
otherwise  it  must  be  neutralized 
with  caustic  soda  before  use.  Lack 
of  uniformity  in  Paranitranilinc  Red 
is  often  due  to  the  vaiying  quality 
of  the  oil  emploj'ed.  Commercial 
beta-naphthol,  as  a  rule,  is  suffi- 
ciently pure  for  use  in  the  dyeing 
*  In  developing  with  diazotized  parani- 
tranilinc solution  hydrochloric  acid  and 
caustic  soda  of  the  right  strength  must  be 
used,  as  free  mineral  acid  prevents  the 
coupling  while  free  caustic  soda  decom- 
poses the  diazo  compound. 


PARANITRANILINE  RED  329 

of  Paranitraniline  Red;  though  sometimes  small  quantities  of  alpha- 
naphthol  may  be  present,  causing  the  color  to  become  brownish  and 
dull.  If  too  great  an  amount  of  naphthol  solution  is  used  for  padding, 
or  if  the  padding  solution  is  too  alkaline,  the  color  will  be  liable  to  crock  and 
also  to  possess  a  yellowish  bronzy  appearance. 

Paranitraniline  Red  is  well  adapted  for  dyeing  yarns  for  fancy  woven 
articles,  fustians,  and  ticking;  for  articles  woven  with  white  which  require 
to  be  boiled-off  and  subsequently  lightly  bleached,  such  as  toweling  and 
shirtings.*  The  introduction  of  the  vat  dyes  during  recent  years,  however, 
has  greatly  lessened  the  use  of  Para  Red.  This  red  cannot  be  used  for 
union  goods  which  have  to  be  cross-dyed  in  strongly  acid  baths,  or  for 
cottons  which  require  to  undergo  a  strong  bleaching,  or  for  goods  which 
must  subsequently  be  treated  with  copper  salts  for  waterproofing.! 

8.  Notes  Respecting  Developing. — In  the  case  of  Paranitraniline  Red, 
Meta-nitraniline  Orange,  Nitrosamine,  and  the  browns,  the  combination 
with  the  naphthol  is  practically  instantaneous,  and  it  is  only  necessary  to 
pass  the  material  quickly  through  the  diazo  solution  and  wash  off  imme- 
diately; in  fact,  the  process  is  frequently  made  continuous.  With  other 
developers  such  as  Azophor  Red,  the  naphthylamines,  nitrophenetidine, 
benzidine  and  tolidine,  dianisidine  and  Azophor  Blue,  the  combination 
proceeds  much  more  slowly,  and  to  insure  complete  coupling  it  is  necessary 

*  The  fastness  to  rubbing  of  Paranitraniline  Red  is  dependent  more  or  less  on  the 
thorough  soaping  the  yarn  receives  after  dyeing,  and  also  upon  the  uniformity  and  thor- 
oughness with  which  the  beta-naphthol  is  fixed,  and  on  the  use  of  a  clear,  slightly  acid 
diazo  solution. 

t  Properties  of  the  Developed  Colors. — Many  of  the  azo  colors  produced  by  the  method 
given  in  the  foregoing  pages  withstand  the  action  of  light  in  a  satisfactory  manner, 
the  reds  and  browns  being  the  fastest,  and  the  blues  and  purplish  reds  the  most  fugitive. 
They  are  also  reasonably  fast  to  washing  with  water  or  neutral  soap,  but  are  rather 
easily  affected  by  boiling  alkalies,  and  particularly  by  mineral  acids,  on  which  latter 
account  they  should  not  be  employed  for  the  dyeing  of  cotton  warps  which  are  to  be 
subsequently  cross-dj^ed  with  white  wool.  The  colors  vary  much  in  their  behavior 
under  the  action  of  steaming.  Paranitraniline  Red  becomes  duller  by  even  a  short  steam- 
ing, but  the  red  produced  by  the  azophor  developer  is  said  to  be  unaffected.  On  the 
other  hand,  the  brown  produced  by  paranitraniline  in  conjunction  with  copper  is 
inproved  by  a  slight  steaming,  as  are  also  the  claret  browns  obtained  by  the  use  of 
benzidine  and  tolidine.  The  dianisidine  and  azophor  blues  become  greener  and 
brighter  by  a  short  steaming.  Many  of  the  azo  colors  are  volatile  when  subjected  to  a 
dry  heat,  or  even  volatilize  slowly  at  ordinary  temperatures.  Thus  they  are  liable  to 
mark  off  when  subjected  to  hot  pressing.  The  colors  are  not  usually  injuriously  affected 
by  dilute  solutions  of  bleaching  powder  or  other  oxidizing  agents,  but  are  readily  de- 
stroyed by  reducing  agents,  which  act  as  discharges.  The  reds  are  particularly  sensitive 
to  the  action  of  metallic  salts,  for  instance,  copper  salts  convert  the  red  into  a  brown.  In 
all  operations,  therefore,  contact  with  copper  or  iron  should  be  avoided,  the  vessels 
employed  being  constructed  of  stone,  wood,  or  preferably,  earthenware.  The  injurious 
effect  of  copper  salts  may,  however,  be  neutralized  by  the  addition  of  o.xalate  of  ammonia 
to  the  developing  solution. 


330  DEVELOPED  TtYES  ON  COTTON  AND  SILK 

to  allow  the  material  to  remain  saturated  with  the  diazo  solution  for  five, 
ten,  or  even  thirty  minutes  before  washing  off.  In  the  three-bath  process 
for  blues,  the  material  is  passed  straight  out  of  the  diazo  solution  into  the 
sodium  acetate  bath  and  allowed  to  remain  for  fifteen  minutes;  it  being 
only  at  this  stage,  when  the  aciditj'  of  the  diazo  solution  is  neutralized,  that 
complete  combination  occurs.* 

The  diazo  solutions  are  usually  rather  stable  in  the  acid  condition,  and 
may  be  kept  for  a  day  or  two  in  a  dark  cool  place;  but  in  the  presence  of 
copper  salts,  or  when  neutralized  with  sodium  acetate  or  other  alkali, 
they  readilj'  decompose.  For  this  reason  the  addition  of  the  copper  salt 
or  of  an  alkali  must  only  take  place  immediately  before  using.  The 
amount  of  diazo  solution  in  the  developing  bath  should  be  as  small  as  pos- 
sible, and  the  bath  should  be  contmuously,  or  very  frequently,  replenished 
with  fresh  solution. 

It  is  veiy  unportant  that  the  material  should  be  quickly  and  regularly 
impregnated  with  the  developing  solution,  avoiding  any  mere  capillary 
distribution  of  the  liquid,  which  leads  to  irregularity.  The  necessity  of 
this  is  easily  recognized  if  a  strip  of  naphthol-prepared  cloth  is  partially 
immersed  in  a  diazo  solution  and  allowed  to  remain  at  rest  for  a  minute 
before  complete  immersion;  under  which  conditions  it  will  be  found  that 
that  portion  of  the  strip  which  was  at  first  immediately  above  the  surface 
of  the  liquor  develops  a  paler  color.  This  is  due  to  the  exhaustion  of  the 
diazo  solution  in  immediate  contact  with  the  cotton,  the  Uquor  devoid  of 
developer  then  rising  by  capillarity  and  diluting  the  naphthol  prepare. 

Cotton  warps  are  most  conveniently  developed  bj^  running  the  yarn 
continuously  through  the  solution.  Hanks  may  be  placed  on  reels  or 
immersed  by  hand,  taking  care  in  the  latter  case  to  hold  the  hank  loosely, 
so  that  the  solution  may  have  free  access.  Thin  cloth  may  often  be  satis- 
factorily treated  by  merely  running  in  the  open  width  between  a  pair  of 
rollers,  of  which  the  lower  one  revolves  in  the  liquor;  but  thick  or  closely 
woven  material  should  be  passed  several  times  through  the  solution,  and 
finally  through  the  squeezing  rolls. 

*  In  using  meta-phenylene-diamine  or  meta-tolu5'lene-<iiamme,  in  order  to  prevent 
the  formation  of  Bismarck  Brown  (by  combination  of  the  developer  with  itself)  it  is 
best  to  add  2.5  grams  of  soda  ash  per  10  lbs.  of  cotton.  This  addition  is  made  to  the 
bath  together  with  the  developer.  Nerogene  D  (which  is  a  chlorinated  diamine)  is 
used  as  follows  (Berlin): 

90  grams  Nerogene  D  are  dissolved  in 

300  cc.  water,  and  add 
90  grams  hydrochloric  acid. 

Use  this  for  developing  10  kilos  (22  lbs.)  of  cotton,  adding  to  the  bath  with  the  devel- 
oper 

300  grams  soda  ash. 


MINOR  NAPHTHOL  DYES  331 

In  the  case  of  slowly  developing  developers,  such  as  those  mentioned 
in  a  foregoing  paragraph,  it  will  be  found  advantageous  to  thicken  the  diazo 
solution  with  flour,  starch,  or  gum,  as  this  greatly  adds  to  the  production 
of  level  colors.  The  same  course  is  sometimes  adopted  for  the  grounding 
with  naphthol  for  these  developers,  since  the  naphthol  is  then  less  liable 
to  dissolve  off  the  material  before  being  rendered  insoluble  by  combination 
with  the  developer.  When  a  thickener  is  required  gum  tragacanth  or 
wheat  flour  is  the  most  satisfactory.  A  thickened  grounding  may  be  pre- 
pared as  follows:  Dissolve  250  grams  of  beta-naphthol  in  300  grams  of 
caustic  soda  (70°  Tw.)  and  1000  cc.  of  water.  Dissolve  also  50  grams  of 
gum  tragacanth  in  1000  cc.  of  water.  Mix  the  two  solutions  and  dilute 
to  10  liters.  The  thickened  diazo  solutions  may  contain  from  3  to  5  grams 
of  tragacanth  or  5  to  15  grams  of  flour  per  liter. 


Fig.  175.— Maoliine  for  Paddinp;  Cotton  Yarn.     (Zittauer.) 

9.  Other  Naphthol  Dyes. — The  following  naphthol  colors  may  be  dyed 
by  the  same  general  process  as  Para  Red.  They  are  used  but  little  for  the 
dyeing  of  cotton  yarn,  though  sometimes  employed  for  cotton  pieces. 
They  have  a  much  more  extensive  use  in  calico-printing.* 

*  Other  naphthol  colors  of  minor  importance  are:  Paranitraniline  Brown,  made  by 
boiling  Paranitraniline  Red  in  a  solution  of  copper  sulphate;  it  may  also  be  made 
directly  by  using  an  alkaline  copper  solution  in  admixture  with  the  naphthol  preparation. 

Amino-azo-benzene . — This  developer  produces  a  somewhat  bluer  shade  of  red  than 
beta-naphthylamine,  the  developing  bath  being  prepared  as  follows :  14  parts  of  amino- 
azo-benzene  are  treated  with  23.6  parts  of  hydrochloric  acid  (36°  Tw.)  and  200  parts  of 
water.  Then  add  4.6  parts  of  sodium  nitrite  in  100  parts  of  water.  Stir  for  fifteen 
minutes,  filter,  and  before  using  add  30  parts  of  ammonium  acetate,  and  dilute  to  1000 
parts. 

Azo  Garnet. — This  color  is  produced  by  using  amino-azo-toluene  as  the  developer, 
this  base  being  sold  as  the  hydrochloride.  Dissolve  26  parts  of  amino-azo-toluene  salt 
in  200  parts  of  water,  and  add  23.6  parts  of  hydrochloric  acid  (36°  Tw.)  and  a  solution 


332  DEVELOPED  DYES  ON  COTTON  AND  SILK 

Dianisidine  Blue  is  prepared  from  a  beta-naphthol  ground  coupled  with 
diazotizcd  dianisidine.*  This,  however,  gives  oi\\y  a  dull  violet  color,  but 
when  treated  with  copper  compounds  a  beautiful  fast  blue  is  obtained. 
While  this  color  is  fast  to  washing  and  light,  f  it  is  unfortunately  very  sensi- 
tive to  acids  and  perspiration.  Attempts  have  ])(H>n  made  to  improve  it  in 
this  respect  by  the  use  of  l^eta-oxynaphthoic  acid,  F-acid,  or  dioxynaph- 
thalene  as  an  addition  to  the  naphthol  solution.  A  special  naphthol  pi'cp- 
aration  containing  these  mixtures  is  marketed  as  Naphthol  D.  Diazo- 
tized  dianisidine  in  a  stable  form  is  also  put  on  the  market  under  the  name 
of  Azophor  Blue  D. 

Alpha-naphthylamine  Claret  is  l)cta-naphthol  combined  with  diazo- 
tized  alpha-naphthylamine ;  t    it  gives  a  rather  bright  bluish  shade  of 

of  4.6  parts  of  sodium  nitrite  in  100  parts  of  water.  Stir  for  fifteen  minutes,  filter, 
and  add  30  i)arts  of  ammonium  acetate,  and  dilute  to  100  parts. 

Azo  Maroon. — Benzidine  (diamino-diphenyl)  and  tolidine  (its  dimethyl  compound) 
produce  in  conjunction  with  beta-naphthol  maroon  shades  of  a  very  similar  character. 
The  padding  is  done  in  the  usual  manner  and  the  developing  bath  is  prepared  as  follows: 
18  parts  of  benzidine  (or  21  parts  of  tolidine)  are  dissolved  in  63  parts  of  hydrochloric 
acid  (36°  Tw.)  and  300  parts  of  water;  then  15  parts  of  sodium  nitrite  in  100  parts  of 
water  are  run  in;  stir  for  fifteen  minutes,  filter,  and  add  40  grams  of  sodium  acetate,  and 
dilute  to  1000  parts. 

Nilro-orUio-toluidine  produces  a  bright  reddish  orange  color  on  a  beta-naphthol 
prepare,  while  mcta-niiranilinc  gives  a  yellower  shade.  The  padding  solution  is  prepared 
in  the  same  manner  as  for  reds,  and  the  developing  baths  in  the  following  manner:  15 
parts  of  ortho-nitro-toluidine  or  14  parts  of  meta-nitraniline  are  dissolved  in  26  parts 
of  hydrochloric  acid  (36°  Tw.)  and  200  parts  of  water.  Then  diazotize  by  adding  4.6 
parts  of  sodium  nitrite  in  100  parts  of  water.  Stir  fifteen  minutes,  filter,  and  add  30 
parts  of  sodium  acetate,  and  dilute  to  1000  parts. 

Azo  Black  Base  O  is  a  patented  product  which  on  a  beta-naphthol  prepare  produces 
a  purplish  black.  Mixed  with  the  necessary  quantity  of  sodium  nitrite  it  is  sold  as 
Azo  Black  Base  ON.  It  is  more  adapted  for  printing  than  for  dyeing  purposes.  The 
naphthol  prepare  is  made  with  30  grams  of  beta-naphthol,  75  grams  of  caustic  soda 
(36°  Tw.)  and  1  liter  of  water.  The  develoi)ing  bath  is  prepared  with  53  grams  of  Azo 
Black  Base,  130  grams  of  hydrochloric  acid  (36°  Tw.),  32  grams  of  sodium  nitrite,  and 
900  cc.  of  water.  Stir  twenty  minutes,  strain,  and  before  using  add  30  grams  of  sodium 
acetate.     If  required  for  printing,  the  solution,  of  course,  must  be  suitably  thickened. 

*  The  dianisidine  is  prepared  as  follows:  3  parts  of  dianisidine  salt  in  10  parts  of 
water  are  well  mixed  with  5  parts  of  hydrochloric;  acid  in  10  parts  of  water;  add  2  parts  of 
sodium  nitrite  in  10  parts  of  water  and  2  j)arts  of  copper  chloride  of  77°  Tw.  Dilute 
with  water  to  250  parts  and  neutralize  with  sodium  acetate. 

t  Dianisidine  Blue  is  faster  to  light  on  cotton  than  Indigo;  it  would  doubtless  be 
much  more  extensively  used  than  it  is  if  it  were  not  for  the  fact  that  it  lacks  fastness  to 
acids  and  perspiration. 

J  The  diazo  solution  of  alpha-naphthylamine  may  be  prepared  as  follows :  143  grams 
of  alpha -nai)hthylamine  are  melted  in  2  liters  of  hot  water,  then  add  200  grams  of  hydro- 
chloric acid  (28°  Tw.)  and  heat  on  the  water  bath  until  all  is  dissolved.  Next  add  190 
grams  of  hydrochloric  acid  and  stir  until  quite  cold.  A  paste  of  the  hydrochloride  is 
thus  obtained,  but  all  goes  into  solution  again  when  the  nitrite  is  added.     Into  the  well- 


PRINCIPAL   DEVELOPED   DYES 


333 


red  very  fast  to  acids  and  washing,  but  of  no  great  fastness  to  light.  The 
diazotized  naphthylamine  solution  is  very  easily  decomposed  and  must  be 
kept  cooled  to  about  40°  F.  with  ice. 

Chloranisidine  Scarlet  is  prepared  from  beta-naphthol  and  diazotized 
chloranisidine.  The  color  has  good  fastness  to  light,  washing,  and  even  a 
moderate  fastness  to  bleaching  with  chlorine. 

Nitrophenetidine  has  the  composition  CgH3(OC2H5)NH2N02,  and  is 
sold  as  Blue  Red  0.  In  conjunction  with  beta-naphthol  it  gives  a  bluish 
red  or  pink.  For  a  pink  shade  the  beta-naphthol  bath  is  made  of  |  to  xV 
the  usual  strength,  or  2  to  5  grams  per  liter.* 


10. 


Alkali  Azo  Violet 
Alkali  Blue  Black 
Azidine  Black  BHN 
Aaidine  Direct  Blacks 
Azidine  Fast  Red 
Azidine  Green  2G,  2B 
Azidine  Violet 
Azo  Mauve 
Benzamine  Brown  M 
Benzo  Azurine  3R 
Benzo  Fast  Black 
Chlorazol  Browns 
Chlorazol  Fast  Yellow 
Columbia  Brown 
Cotton  Black  RW 
Cotton  Brown  AN 
Cotton  Fast  Reds 
Cupranil  Browns 
Diamine  Azo  Black 
Diamine  Azo  Blue 
Diamine  Azo  Bordeaux 


List  of  the  Principal  Developed  Dyes 

Diamine  Azo  Scarlet  Diazethyl  Black  B,  R 

Diamine  Beta  Blacks  Diazine  Black  H 

Diamine  Blacks  BH,  BO,  RO  Diazo  Blacks  (all  brands) 


Diamine  Blue  2B,  BH 
Diamine  Blue  Black 
Diamine  Bronze 
Diamine  Brown  M,  S,  V 
Diamine  Cutch 
Diamine  Heliotrope 
Diamine  Jet  Black  SS 
Diamineral  Blue 
Diaminogenes 
Diaminogene  Blues 
Diaminogene  extra 
Diaminogene  Sky  Blues 
Dianil  Black  ES 
Dianil  Brown 
Dianil  Dark  Blue 
Dianol  Blue  BH 
Dianol  Diazo  Blacks 
Dianol  Steel  Blue 


Diazo  Blues 
Diazo  Blue  Black 
Diazo  Bordeaux 
Diazo  Brilliant  Black 
Diazo  Brilliant  Orange 
Diazo  Brilliant  Scarlet 
Diazo  Brown 
Diazo  Dark  Blue 
Diazo  Fast  Black 
Diazo  Fast  Bordeaux  BL 
Diazo  Fast  Red  7BL 
Diazo  Fast  Violet 
Diazo  Geranine  B 
Diazo  Indigo  Blue 
Diazo  Navy  Blue 
Diazo  Olive  G 
Diazo  Rubine 
Diazo  Sky  Blue 


cooled  liquor  pour  550  cc.  of  nitrite  solution  (150  grams  of  sodium  nitrite  per  liter),  intro- 
ducing it  below  the  surface  and  stu-  well.  The  temperature  should  not  rise  above 
30°  F.  After  standing  for  fifteen  minutes  filter  and  dilute  to  10  liters.  Shortly  before 
using  add  300  grams  of  sodium  acetate.  Alpha-naphthylamine  Salt  S  is  the  sulphate 
of  alpha-naphthylamine  and  is  a  convenient  form  for  use;  for  diazotizing  use  192  grams 
with  100  grams  of  concentrated  sulphuric  acid  and  520  cc.  of  nitrite  solution.  Care 
must  be  taken  to  avoid  the  use  of  impure  alpha-naphthylamine,  as  this  will  produce 
spotted  dyeings.  Beta-naphthylamine  may  be  used  in  the  same  way;  it  gives  a  bluer 
and  duller  shade  of  red  than  paranitraniline. 

*  The  developing  bath  is  prepared  as  follows:  Dissolve  14.5  parts  of  nitrophenetidine 
in  9.5  parts  of  hydrochloric  acid  (36°  Tw.)  and  200  parts  of  water.  Then  run  in  1.5 
parts  of  sodium  nitrite  dissolved  in  50  parts  of  water.  Stir  for  fifteen  minutes,  strain, 
and  just  before  using  add  5  parts  of  sodium  acetate.  Stir  till  dissolved  and  dilute  to 
1000  parts.  The  development  is  not  completed  by  a  single  passage  through  the  solution 
and  the  material  should  be  allowed  to  remain  saturated  with  the  developing  solution  for 
fifteen  minutes.     Then  wasli  well  and  soap. 


334 


DEVELOPED  DYES  ON  COTTON  AND  SILK 


Diazogen  Black 
Diazogen  Bordeaux 
Diazogen  Brown 
Diazogen  Corinth 
Diazogen  Reds 
Diazogen  Scarlet 
Diazogen  Violet  5R 
Diazurine  B 
Diazyl  Black 
Direct  Black  BH      • 
Direct  Brown 
Direct  Dark  Brown 
Direct  Deep  Blacks 
Direct  Fast  Brown 
Direct  Indigo  Blues 
Direct  Indone  Blue 
Fast  Cotton  Reds 
Hessian  Bordeaux 
Indigene  Blacks 
Indigene  Blues 
Indigo  Blue  B 
Ingrain  Blacks 
Melanogen  Blue  BH 


Melantherine 
Naphthamine  Blacks 
Naphthamine  Blue  BE 
Naphthamine  Browns 
Naphthamine  Fast  Blacks 
Naphthamine  Greens 
Naphthogene  Blues 
Neropaline 

Niagara  Fast  Black  M 
Osfamine  Black 
Osfanil  Blacks 
Oxamine  Black  A 
Oxamine  Blue  BG 
Oxamine  Blue  3R 
Oxamine  Brown  B,  R 
Oxamine  Violet 
Oxy  Diaminogenes 
Paramine  Navy  Blue 
Pluto  Black  L 
Pluto  Brown 
Polychromine  A  and  B 
Primuline  (all  brands) 
Renol  Black  SF 


Renol  Blue  B 
Renol  Brown  MB 
Renol  Violet 
Renolamine  Blacks 
Renolamine  Red 
Rosanthrene 
Rosanthrene  Bordeaux 
Rosanthrene  Violet  5R 
Sulphines 
Thiochromogene 
Titan  Fast  Blacks 
Titan  Orange 
Tohiylene  Blue  Black 
Toluylene  Brown  G 
Triazol  Blacks 
Triazol  Dark  Blues 
Yellow  PR 
Zambesi  Blacks 
Zambesi  Blue 
Zambesi  Browns 
Zambesi  Gray 
Zambesi  Indigo  Blue 


11.  List  of  Dyestuffs  Suitable  for  Shading  Developed  Colors 
(or  unaffected  by  diazotizing) 


Aurophenine  O 
Columbia  Yellow 
Curcumine  S 
Diamine  Black  HW 
Diamine  Blue  3R 
Diamine  Bordeaux  S 
Diamine  Fast  Black  F 
Diamine  Fast  Blue 
Diamine  Fast  Red  F 
Diamine  Fast  Scarlet 

12.  List 
Benzamine  Browns 
Benzo  Brown  G 
Benzo  Nitrol  Black 
Benzo  Nitrol  Bordeaux 
Benzo  Nitrol  Browns 
Chicago  Blue,  B,  R 
Chlorazol  Browns 
Chlorazol  Dark  Navy 
Chlorazol  Green 
Chlorazol  Red 
Chlorazol  Violets 
Chrysamine 
Columbia  Black  R,  BB 
Columbia  Fast  Blacks 


Diamine  Fast  Yellow 
Diamine  Green  B,  G 
Diamine  New  Blue  R 
Diamine  Orange  B,  G 
Diamine  Steel  Blue 
Diamine  Violet  N 
Diamineral  Blue  R 
Diamineral  Brown  G 
Dianil  Blues 


Dianil  Claret  Red  G,  B 
Dianil  Direct  Yellow 
Dianil  Fast  Brown  B 
Dianil  Orange  G,  F 
Dianil  Red,  R,  4B,  lOB 
Dianil  Yellows 
Oxydiamine  Violet  B,  R,  G 
Oxydianil  Yellow  O 
Thioflavine  S 


of  Dyestuffs  Suitable  for  the  Coupling  Process 


Congo  Browns 
Cotton  Black 
Cotton  Brown  AN 
Cotton  Yellows 
Cotton  Yellow  G 
Diamine  Bengal  Blue 
Diamine  Bengal  Blue  G 
Diamine  Black  B,  BR,  R 
Diamine  Blue  NC,  3B 
Diamine  Bronze  G 
Diamine  Brown  MR,  S,  B, 

M 
Diamine  Cutch 
Diamine  Fast  Yellow  A 


Diamine  Gray  G 

Diamine  Jet  Black 

Diamine  Nitrazol  Black  B 

Diamine  Nitrazol  Bordeaux 

Diamine  Nitrazol  Browns 

Diamine  Nitrazol  Green  G 

Diamine  Nitrazol  Orange 

Diamine  Nitrazol  Scarlet 

Diaminogene 

Dianil  Blacks,  CR,  R,  N,  PR 

Dianil  Blue 

Dianil  Brown  B,  D,  3G0,  2G 

Dianil  Orange 

Dianol  Blacks 


EXPERIMENTAL  STUDIES 


335 


Dianol  Coupling  Greens 
Diazo  Brown  G,  R 
Diazogen  Orange 
Direct  Blue  Black 
Direct  Deep  Black  E,  RW 
Direct  Fast  Brown  B 
Direct  Orange 
Naphthamine  Black 
Naphthamine  Blue  BE 
Nitramine  Browns 
Nitranil  Browns 
Osfanil  Blacks 
Oxamine  Blue  BG 
Oxamine  Brown,  3G,  B,  R 
Oxamine  Maroon 
Oxamine  Red 
Oxamine  Violet 


Oxydiamine  Blacks 
Oxydiamine  Brown  G 
Oxydiamine  Carbon 
Oxydiamine  Orange 
Para  Blues 
Para  Bronze 
Para  Brown 
Para  Diamine  Blacks 
Para  Fast  Green 
Para  Garnet  G 
Para  Green 
Para  Olive  G 
Para  Orange 
Para  Scarlet  G 
Para  Yellow 
Paranil  Bordeaux 
Paranil  Browns 


Paranil  Yellow 
Pluto  Brown  R,  GG 
Pluto  Orange  G 
Polychromine 
Primuline 

Pyramine  Orange  3G 
Renol  Blacks 
Renol  Brown  R,  PR 
Renol  Orange 
Renol  Orange  R 
Renolazine  Green 
Sultan  Orange 
Toluylene  Brown  G,  R 
Toluylene  Orange  G,  R 
Triazol  Blacks 
Thiazol  Yellows 


13.  Experimental  Exp.  123.  General  Method  of  Applying  Developed  Dyes. — Certain 
of  the  substantive  dyes  may  be  applied  to  cotton  and  then  changed  by  chemical 
treatment  into  other  dyestuffs  which  may  be  of  a  totally  different  color,  and  are  fre- 
quently much  faster  or  deeper  in  shade  than  the  original  color  from  which  they  have 
been  derived.  In  other  words,  the  dyestuff  is  built  up  within  the  fiber  itself  just  as 
ordinary  dyestuffs  are  formed  without  reference  to  the  fiber.  This  class  of  substantive 
dyes  is  known  as  the  "  developed  "  or  "  diazotized  "  colors,  from  the  chemical  processes 
through  which  they  pass.  These  dyes  form  a  rather  important  class  of  colors,  the  value 
and  adaptability  of  which  are  constantly  growing.  Primuline  was  the  first  of  these 
dyes  discovered,  and  is  still  the  most  important  one  in  use  and  may  be  taken  as  the  type 
of  the  entire  class.  Dye  a  test  skein  of  cotton  yarn  in  a  bath  containing  6  per  cent  of 
Primuline,  20  per  cent  of  salt,  and  1  per  cent  of  soda  ash;  enter  at  140°  F.,  gradually 
raise  to  the  boil  and  dye  at  that  temperature  for  one-half  hour.  It  will  be  noticed  that 
this  is  simply  the  general  method  for  applying  substantive  dyes,  and  that  the  color 
obtained  is  yellow.  Rinse  the  skein  in  fresh  water  and  pass  into  a  cold  bath  containing 
5  per  cent  of  sodium  nitrite  and  6  per  cent  of  sulphuric  acid;  work  for  about  ten  minutes. 
It  will  be  noted  that  the  yellow  color  of  the  dye  is  altered  to  a  brownish  yellow  by  this 
treatment,  and  if  the  odor  of  the  bath  is  observed  the  presence  of  nitrous  acid  will  be 
noted.  Rinse  the  skein  with  cold  water,  and  immediately  pass  into  a  third  bath  con- 
taining 2  per  cent  of  beta-naphthol  solution;  work  cold  for  fifteen  minutes,  then  wash 
well  and  dry.  When  placed  in  the  third  bath  it  will  be  noticed  that  the  skein  turns  a 
bright  red  color,  which  is  due  to  the  new  dyestuff  which  has  thus  been  formed  within 
the  fiber.  In  the  first  bath  the  Primuline  acts  merely  as  a  substantive  dye,  and  gives  a 
yellow  color  which  possesses  no  fastness  and  is  unimportant.*  The  second  solution  is 
termed  the  "  diazotizing  "  bath.     The  action  of  the  sodium  nitrite  on  the  sulphuric  acid 

*  The  final  intensity  of  the  color  obtained  with  Primuline  will  depend  entirely  upon 
the  amount  of  dyestuff  fixed  on  the  fiber  in  the  first  bath;  hence  in  order  to  obtain 
uniform  shades  on  successive  lots  of  dyed  goods,  it  is  necessary  to  always  use  definite 
amounts  of  dyestuff.  With  6  per  cent  of  Primuline  in  the  starting  bath  a  full  shade  of 
Primuline  Red  will  be  obtained;  for  a  standing  bath  about  3  per  cent  of  Primuline  will  be 
required,  but  no  further  addition  of  salt  or  soda  need  be  made.  The  primrose  yellow 
shade  of  Primuline  dyed  direct  is  fast  to  alkali,  but  is  turned  orange  by  acid,  and  is  also 
xugitive  to  light. 


336 


DE\^LOPED  DYES  ON  COTTON  AND  SILK 


is  to  liberate  nitrous  acid  and  form  sodium  suljjhate;  the  nitrous  acid  acts  on  the  dye- 
stuff  in  such  a  manner  that  the  amino  groups  (NH2)  present  are  changed  into  what  are 
known  as  "  diazo  "  groups,  N  :  N.  This  diazo  group  combines  with  the  sulphuric  acid 
present  in  the  bath  and  forms  primuline-diazo-sulphate.  The  diazo  body  is  very 
unstable,  hence  the  bath  must  be  employed  cold,  and  the  cotton  must  be  passed  from 
this  bath  as  soon  as  possible  into  the  third  bath,  for  if  the  diazotized  material  is  allowed 
to  stand  for  any  length  of  time,  esi^ecially  if  exposed  to  strong  light,  the  diazo  body  will 
decompose  and  the  eventual  color  will  be  spoiled.  The  diazotizing  bath  should  smell 
distinctly  of  nitrous  acid,  and  if  such  is  not  the  case,  more  sodium  nitrite  and  acid  should 
be  added.  Care  should  be  taken  that  this  bath  does  not  become  heated  by  leak}'  steam- 
pipes,  etc.  Sometimes,  in  fact,  ice  is  added  to  this  bath  for  the  purpose  of  keeping 
the  temperature  down  (hence  these  colors  are  sometimes  spoken  of  as  "  ice  colors  "); 
but  if  the  bath  is  kept  at  the  ordinary  temperature  of  water  (about  60  to  70°  F.)  no 
artificial  cooling  is  necessary.  The  third  bath  is  termed  the  "  developing  "  bath,  and 
the  beta-naphthol  (or  other  like  body)  is  spoken  of  as  the  "  developer."  Its  function 
is  to  combine  with  the  unstable  diazo  body  to  give  the  new  and  permanent  coloring 


Fig.  176.— Yarn  Washer.     (Dehaitre.) 


matter.  This  bath  should  also  be  cold,  otherwise  the  diazo  body  on  first  entering  the 
bath  will  be  decomposed  before  it  has  had  a  chance  to  become  fixed  by  the  developer. 
Beta-naphthol  is  not  very  soluble  in  water  (especially  cold  water),  hence,  before  adding 
it  to  the  bath  it  is  advisable  to  dissolve  it  in  a  little  hot  water  together  with  its  weight 
of  soda  ash,  or  caustic  soda,  and  add  this  solution  to  the  developing  bath. 

Exp.  124.  Showing  the  Action  of  Heat  on  the  Diazo  Body. — Dye  a  skein  of  cotton 
yarn  as  before  with  6  per  cent  of  Primulinc;  rinse  and  diazotize  in  a  bath  containing  5 
per  cent  of  sodium  nitrite  and  6  per  cent  of  sulphuric  acid;  work  for  ten  minutes  at  a 
temperature  of  180°  F.,  then  rinse,  and  pass  into  the  developing  bath  prepared  as  above 
described;  work  cold  for  ten  minutes,  then  wash  and  dry.  Compare  the  color  obtained 
on  the  skein  with  that  on  the  one  in  the  previous  experiment.  Dye  another  skein  of 
cotton  3'arn  with  6  per  cent  of  Primuline  as  before,  and  diazotize  cold  as  in  the  previous 
e.xperiment.  -  Then  wash  the  skein  in  hot  water  for  ten  minutes,  and  afterwards  develop 
as  already  described  in  the  beta-naphthol  bath  cold  for  ten  minutes.  Notice  the  influ- 
ence of  the  hot  washing  on  the  eventual  color.     Dye  another  skein  with  6  per  cent  of 


EXPERIMENTAL  STUDIES  337 

Primuline  as  before;  diazotize  cold,  and  expose  to  the  air  for  several  hours;  then  develop 
as  usual  in  the  beta-naphthol  bath  cold  for  ten  minutes.  Notice  the  influence  of  the  long 
exposure  on  the  color. 

Exp.  125.  Developed  Black  on  Cotton. — Although  there  are  several  black  dyes  among 
the  substantive  colors,  yet  they  do  not  yield  very  satisfactory  colors  either  as  regards 
depth  of  tone  or  fastness  to  bleeding  when  dyed  directly .  Some  of  these  may  be  diazo- 
tized  and  developed,  however,  and  so  produce  black  colors  of  great  beauty  and  fastness. 
Dye  a  skein  of  cotton  yarn  in  a  bath  containing  6  per  cent  of  Diamine  Black  BH,*  20 
per  cent  of  common  salt,  and  1  per  cent  of  soda  ash;  enter  at  140°  F.,  gradually  raise  to 
the  boil,  and  dye  at  that  temperature  for  one-half  hour;  rinse,  and  diazotize  as  usual, 
and  then  develop  with  2  per  cent  of  phenylene-diamine  salt  in  same  manner  as  employed 
for  beta-naphthol;  wash  well  and  dry.  Phenylene-diamine  salt  is  best  dissolved  previously 
to  its  addition  to  the  bath  with  a  little  soda  ash.  Test  the  black  thus  obtained  for  fastness 
to  washing  and  cross-d3'eing.  Also  preserve  a  sample  of  the  color  before  diazotization 
and  compare  it  in  tone  of  color  with  the  developed  dyeing;  also  test  the  fastness  of  the 
direct  dyeing  to  washing  and  cross-dyeing,  and  compare  these  results  with  those  of  the 
developed  dyeing. 

Exp.  126.  Developed  Brown  on  Cotton. — Dye  a  test  skein  of  cotton  in  the  usual 
manner  with  3  per  cent  of  Diamine  Cutch,  20  per  cent  of  glaubersalt,  and  1  per  cent  of 
soda  ash.  Rinse,  diazotize,  and  develop  for  fifteen  minutes  in  a  bath  containing  4  grams 
of  soda  ash  per  liter  of  water  at  120°  F.  The  direct  color  obtained  with  this  dye  has  no 
value,  but  the  diazotized  color  developed  in  this  manner  with  soda  ash  gives  a  fine 
cutch  brown  shade  very  fast  to  washing  and  acids,  of  moderate  fastness  to  light  and 
fairly  fast  even  to  chlorine.  This  dye  is  a  derivative  of  naphthylene-diamine  coupled 
with  alpha-naphthylamine.  The  treatment  with  soda  ash  converts  the  alpha-naphthy- 
lamine  into  alpha-naphthol,  and  thus  forms  a  new  dyestuff. 

Exp.  127.  Developed  Blue  on  Cotton. — Dye  a  test  skein  of  cotton  in  the  usual  manner 
with  3  per  cent  of  Diaminogene  Blue  BB,  20  per  cent  of  glaubersalt  and  1  per  cent  of 
soda  ash.  Diazotize  and  develop  with  beta-naphthol.  The  blue  so  obtained  is  quite 
fast  to  washing  and  acids.  Dark  navy  blue  shades  may  be  obtained  by  using  Diamine 
Azo  Blue  R,  diazotizing  and  developing  with  Naphthylamine  Ether  N. 

Exp.  128.  Shading  of  Developed  Dyeings  with  Other  Substantive  Dyfes. — As  a 
number  of  the  substantive  dyes  are  not  appreciably  changed  on  being  subjected  to  the 
diazotizing  and  developing  processes,  they  may  be  employed  for  the  purpose  of  shading 
off  the  usual  developed  colors.  Dye  a  skein  of  cotton  yarn  in  the  usual  manner  with  1 
per  cent  of  Zambesi  Pure  Blue  4B  and  1  per  cent  of  Dianil  Yellow  3G.  Diazotize  and 
develop  as  usual  with  beta-naphthol.  As  the  yellow  remains  unaffected  by  the  process  a 
green  color  will  be  the  result.  By  using  suitable  combinations  in  this  manner  a  large 
number  of  varied  shades  may  be  obtained  among  the  developed  dyes. 

Exp.  129.  After-treatment  of  a  Developed  Dye  with  Bluestone. — This  process  is  for 
the  purpose  of  making  the  colors  faster  to  light.  As  already  stated,  the  fastness  of  the 
developed  colors  to  light  is,  as  a  rule,  no  greater  than  that  of  the  original  dyeing.  All 
of  the  developed  colors,  however,  are  not  susceptible  to  this  treatment,  either  because 
their  fastness  is  in  no  wise  enhanced  or  because  their  shade  is  destroyed  by  the  action  of 

*This  dye  (Schultz  333)  is  the  principal  one  employed  for  the  production  of  developed 
blacks.  It  is  known  under  a  wide  variety  of  names,  depending  on  the  maker,  as  Dianil 
Black  ES,  Naphthamine  Black  CE,  Renolamine  Black  BH,  Azidine  Black  BH,  Direct 
Black  HB,  Diazo  Black  BH,  Diazine  Black  H,  Oxamine  Black  BHN,  etc.  It  gives  a 
very  fine  deep  shade  of  black  fast  to  washing  and  acids.  When  developed  with  beta- 
naphthol  it  gives  a  bluish  black,  while  with  Naphthylamine  Ether  N  a  navy  blue  shade  is 
obtained. 


338  DEVELOPED  DYES  ON  COTTON  AND  SILK 

the  metallic  salt.  In  some  cases,  however,  and  especially  with  a  number  of  the  blue 
dyes,  the  after-treatment  has  the  effect  of  greatly  increasing  the  fastness  without 
materially  injuring  the  shade.  Generally  the  process  is  carried  out  in  the  same  manner 
as  with  the  substantive  dyes,  using  a  second  bath  containing  a  solution  of  bluestone 
together  with  a  small  amount  of  acetic  acid.  In  a  few  instances,  however,  the  blue- 
stone  may  be  added  directly  to  the  diazotizing  bath,  and  the  diazotization  and  develoj> 
ment  carried  out  as  usual:  (a)  Dye  a  test  skein  of  cotton  in  the  usual  manner  with  2 
per  cent  of  Benzo  Azurine  G;  rinse,  diazotize  and  develop  with  beta-naphthol.  Rinse 
and  treat  for  twenty  minutes  in  a  boiling  bath  containing  2  per  cent  of  bluestone  and 
1  per  cent  of  acetic  acid,  (h)  Dye  two  test  skeins  of  cotton  in  the  usual  manner  with 
6  per  cent  of  Zambesi  Black  BR;  rinse  and  diazotize  the  one  with  the  addition  of  5 
per  cent  of  bluestone  to  the  bath,  and  the  other  without  the  addition  of  the  bluestone. 
Develop  both  skeins  with  meta-toluylene-diamine.  Compare  the  two  skeins  thus  dyed 
for  color  and  fastness  to  light  and  washing.  When  the  latter  method  of  after-treatment 
is  used  the  fastness  to  washing  is  not  increased  in  the  same  degree  as  when  the  after- 
treatment  takes  place  in  a  separate  bath.  Both  methods,  however,  appear  to  give  equal 
increase  in  the  fastness  to  light. 

Exp.  130.  Dyeing  by  the  Coupling  Process. — In  this  process  of  dyeing  the  dyestuff 
as  first  applied  to  the  fiber  is  not  diazotized  but  acts  in  the  role  of  a  developer  towards  a 
diazotized  base  with  which  the  dyed  material  is  subsequently  treated.  The  base 
employed  for  coupling  with  the  dyestuff  is  paranitraniline;  a  few  other  bases  of  like 
nature  may  also  be  used,  but  they  are  of  minor  importance.  The  general  process  in 
this  method  of  dyeing  is  to  apply  the  substantive  color  in  the  usual  manner,  rinse,  and 
then  work  for  half  an  hour  in  a  cold  solution  of  the  diazotized  base.  There  are  a  number 
of  substantive  dyes  suitable  for  the  coupling  process,  yielding  mostly  black,  blue,  brown, 
and  yellow  shades.  The  colors  obtained  are  characterized  by  the  same  fastness  to  wash- 
ing and  acids  as  those  produced  by  the  usual  diazotizing  and  developing  process. 
Dye  a  skein  of  cotton  in  the  usual  manner  with  2  per  cent  of  Benzo  Nitrol  Brown  G. 
Rinse  and  treat  with  45  cc.  of  diazotized  paranitraniline  solution,  h  per  cent  of  soda  ash 
and  J  per  cent  of  sodium  acetate.  Work  cold  for  one-half  hour,  then  rinse  and  dry. 
The  diazotized  paranitraniline  solution  is  prepared  as  follows:  20  grams  paranitraniline 
are  dissolved  in  200  cc.  of  boiling  distilled  water;  stir  well  and  add  50  cc.  of  hydrochloric 
acid;  stir,  and  after  complete  solution  add  425  cc.  of  cold  water.  This  will  cause  the 
precipitation  of  paranitraniline  hydrochloride  in  the  form  of  a  yellow  paste.  When 
the  paste  is  quite  cold  add  15  grams  of  sodium  nitrite  dissolved  in  70  cc.  of  cold  water. 
Stir  well  and  in  about  twenty  minutes  a  clear  solution  should  result.  This  is  diluted 
with  cold  water  to  2500  cc.  Keep  this  diazo  solution  in  an  earthenware  or  wooden  vessel 
well  protected  from  light  and  heat,  under  which  conditions  it  may  be  preserv^ed  for  some 
days  without  material  decomposition.  The  alkali  and  sodium  acetate  are  added  to  the 
coupling  bath  for  the  purpose  of  neutralizing  the  acid  present.  The  brown  color 
obtained  in  this  manner  is  very  fast  to  washing  and  even  fulling;  it  will  also  stand 
cross-dyeing,  though  the  fastness  to  light  is  not  particularly  good.  The  couphng  process, 
as  a  rule,  greatly  intensifies  the  shade.  In  the  dyeing  of  coupled  blacks  there  is  no  advan- 
tage to  be  gained  over  the  blacks  produced  by  the  usual  method  of  diazotizing,  and  as 
the  latter  process  is  more  readilj-  carried  out  it  is  to  be  preferred. 

Exp.  131.  Dyeing  Primuline  on  Silk. — Some  of  the  developed  dyes  are  very  suitable 
for  the  dyeing  of  fast  colors  on  silk.  Dye  a  skein  of  silk  in  a  bath  containing  10  per  cent 
of  glaubersalt  and  10  per  cent  of  Primuline;  enter  at  140°  F.,  and  gradually  bring  to  the 
boil  and  dye  at  that  temperature  for  one-half  hour;  rinse,  and  diazotize  and  develop 
with  beta-naphthol  as  already  described  in  the  foregoing  experiments.  This  should 
give  a  good  heavy  red  which  is  fast  to  washing  and  water. 


EXPERIMENTAL  STUDIES  339 

Exp.  132.  Dyeing  a  Developed  Black  on  Silk.— Dye  a  skein  of  silk  yarn  in  a  bath 
containing  10  per  cent  of  glaubersalt  and  10  per  cent  of  Zambesi  Black  D  *  in  the  usual 
manner;  diazotize  and  develop  with  3  per  cent  of  toluylene-diamine.  Wash  well  and 
dry.     Test  this  color  for  fastness  to  washing  and  water. 

*  A  product  known  as  Nerogene  D  is  also  recommended  as  a  developer  for  this  dye. 
This  developer  should  first  be  dissolved  in  water  acidulated  with  hydrochloric  acid,  and, 
after  adding  to  the  bath,  should  be  neutralized  with  soda  ash. 


CHAPTER   XYL 

APPLICATION  OF  MORDANT  DYES 

1.  The  Mordant  Dyes. — As  already  explained  in  studying  the  general 
properties  of  dyestuffs,  the  mordant  dj^es  refer  to  those  colors  which 
require  the  aid  of  a  metallic  mordant  in  order  to  furnish  a  satisfactory  dye- 
ing on  the  fiber.  In  former  years  the  only  distinction  between  mordant 
dyes  and  those  which  could  be  dyed  directly  was  to  call  the  former  "  adjec- 
tive "  dyes  and  the  latter  "  substantive  "  dyes.  Hummel  drew  the  dis- 
tinction by  calling  the  direct  dyeing  colors  "  monogenetic,"  and  the  mor- 
dant colors  "  polygene  tic  " ;  but  these  rather  cumbersome  names  have 
practically^  passed  out  of  the  parlance  of  tinctorial  chemistry.  In  the  early 
development  of  the  coal-tar  dyes,  the  class  of  mordant  colors  practically 
included  only  the  true  alizarines  (derivatives  of  anthracene)  and  most  of  the 
natural  wood  dj^es.  At  the  present  time,  however,  the  mordant  dj'es  are 
to  be  found  in  a  rather  wide  variety  of  gi'oups,  and  the  name  includes 
many  dyes  other  than  those  of  the  true  alizarines.  The  latter  dyes  will  not 
dye  wool  at  all  without  a  mordant,  whereas  there  are  many  mordant  dyes 
now  which  though  they  do  not  give  a  satisfactorily  fast  color  without  the 
aid  of  a  mordant,  nevertheless  will  dye  wool  without  a  mordant.* 

*  A^'hittaker  { Dyeing  with  Coal-Tar  Dyestuffs)  gives  the  following  classification  of 
mordant  dyes : 

Class.  Example. 

Anthracene  dyes  Alizarine 

Monoazo  dyes  Mordant  Yellow  O 

Disazo  dyes  Diamond  Black  F 

Oxazine  dyes  Gallocyanine 

Triphen3'lmethane  dyes  Chrome  \'iolet 

Nitroso  dj^es  Gambine 

Oxj'^quinone  dyes  Alizarine  Black 

Xanthene  dyes  Coerulein 

It  has  been  the  habit  of  the  dj'e  makers  to  call  most  any  color  which  may  be  applied 
on  a  mordant  an  "  alizarine  "  dye,  whether  derived  from  anthracene  or  not.  Of  late 
years,  however,  there  has  been  a  tendency  to  call  such  colors  "  chrome  "  dyes  rather 
than  "  alizarine,"  and  this  is  by  far  a  more  satisfactory  nomenclature.  Alizarine  Yellow 
and  Anthracene  Yellow,  for  instance,  bear  no  chemical  relation  to  alizarine  or  anthra- 
cene. 

340 


MORDANTING  OF  WOOL  341 

The  mordant  dyes  as  a  class  are  particularly  applied  to  wool,  and  give 
the  fastest  colors  to  light  and  washing.  In  trade  they  are  to  be  met 
with  as  both  pastes  and  powders — the  paste  being  used  in  case  the  dye 
is  rather  insoluble  in  water,  and  if  dried  to  a  powder  would  be  difficult 
for  the  dyer  to  use.  This  is  particularly  true  in  the  case  of  alizarines. 
The  powder  dyes  of  the  alizarines  are  usually  in  the  form  of  the  bisulphite 
compounds  which  are  much  more  soluble  in  water.  On  heating  in  the  dye- 
bath  the  bisulphite  compound  dissociates  and  the  insoluble  alizarine  dye 
is  precipitated. 

2.  The  Mordanting  of  Wool. — In  the  dyeing  of  woolen  goods  where 
the  colors  obtained  are  desired  to  be  very  fast,  it  is  nearly  always  neces- 
sary'' to  first  mordant  the  material;  that  is  to  say,  the  wool  must  be  treated 
with  solutions  of  certain  metallic  salts  previous  to  the  dyeing  operation  in 


Fig.  177.— Open  Width  Washer.     (Zittauer.) 

order  to  change  the  chemical  properties  of  the  fiber  in  such  a  manner 
that  on  subsequently  dyeing  a  color-lake  or  combination  with  the  dye- 
stuff  may  be  obtained  which  is  permanent  in  its  nature.  * 

Wool  is  especially  susceptible  to  the  action  of  solutions  of  various 
metallic  salts,  particularly  those  whose  aqueous  solutions  are  more  or  less 
readily  dissociated  with  the  formation  of  insoluble  metallic  hydrates  or 
oxides.  When  boiled  in  a  solution  of  such  a  salt  the  substance  of  the  wool 
fiber  apparently  brings  about  a  dissociation  of  the  metallic  compound  in 
such  a  manner  that  the  hydrate  of  the  metal  is  absorbed  and  firmly  com- 
bined with  the  wool  itself.     Just  exactly  what  takes  place  in  this  fixation 

*  The  term  "  mordant  "  is  derived  from  the  Latin  word  mordere,  to  bite.  According 
to  Hummel  this  term  was  introduced  into  the  dyer's  vocabulary  because  the  early 
French  dyers  considered  that  the  utility  of  these  metallic  salts  used  as  mordants  con- 
sisted in  their  corrosive  action,  the  general  opinion  being  that  they  made  the  textile 
fibers  rough,  and  thus  opened  the  pores  and  rendered  the  fibers  more  suitable  for  the 
entrance  and  penetration  of  the  coloring  matters. 


342  APPLICATION  OF  MORDANT  DYES 

of  the  metallic  compound  by  the  wool  fiber  is  still  a  matter  of  considerable 
discussion,  but  whatever  may  be  the  reason  and  cause  of  the  reaction, 
the  effect  is  well  understood  and  the  process  is  very  largely  employed  in 
dyeing. 

A  dissociation  of  the  mordanting  salts  no  doubt  takes  place,  induced 
and  augmented  both  by  the  dilution  and  the  heating  of  the  solution  and 
the  addition  of  the  various  assisting  agents;  and  furthermore  this  disso- 
ciation is  partly  brought  about  by  the  presence  of  the  fiber  itself  in  the 
boiling  solution. 

While  in  some  cases  a  difficultly  soluble  basic  salt  of  the  metallic 
mordant  may  be  absorbed  by  the  fiber,  in  most  cases  of  mordanting  (on 
wool  at  least)  the  material  which  is  precipitated  in  the  fiber  (or  combined 
in  some  physico-chemical  form  with  the  substance  of  the  fiber)  is  a  metallic 
hydrate  or  oxide.  Most  of  the  metals  which  act  best  as  mordants  for 
wool  are  those  which  rather  easily  form  basic  salts,  resulting  eventually 
in  the  removal  of  the  acid  constituent  of  the  salt,  and  thus  forming  the 
hydrate.  In  the  case  of  mordant  salts  capable  of  forming  basic  com- 
pounds, it  must  be  borne  in  mind  that  there  are  usually  several  steps  pos- 
sible in  the  gradation  of  the  l:)asic  salts  from  the  neutral  salt  to  the  hydrate. 
Taking  aluminium  sulphate  as  an  example  of  this  type  of  salt,  we  have,  for 
instance : 

AI2  (804)3  =  aluminium  sulphate. 

Al2(OH)2  (804)2=  first  basic  salt. 

Al2(OH)4(804)   =  second  basic  salt. 

A12(0H)g  =  aluminium  hydrate. 

The  progressive  formation  of  these  basic  salts  may  be  considered  as  a 
reaction  of  the  salt  with  water  and  the  withdrawal  or  elimination  of  acid, 
as  follows: 

Al2(804)3  +2H  •  OH  =  AI2  (0H)2  (804)2 +H2SO4 

aluminium  sulphate  water  1st  basic  salt  sulphuric  acid 

Al2(OH)2(S04)2+2H-OH  =  Al2(OH)4(804)  +H28O4 

1st  basic  salt  water  2d  basic  salt  sulphuric  acid 

Al2(OH)4(804)  +2H-OH  =  Al2(OH)6  +H2SO4 

2d  basic  salt  water       aluminium  hydrate  sulphuric  acid 

There  is  perhaps  more  or  less  of  a  chemical  reaction  between  the 
wool  and  the  mordanting  salt,  and  this  question  has  been  gone  into  with 
quite  some  detail  by  Liechti  and  Schwitzer  (see  Jour.  Soc.  Dyers  & 
Col.,  1886,  p.  161).  It  is  well  known  that  wool  is  capable  of  combining  with 
relatively  small  amounts  of  sulphuric  acid  when  boiled  in  a  dilute  solution 
of  this  acid,  and  the  acid  so  combined  is  not  removed  by  subsequent  extrac- 
tion with  boiling  water.     Viewed  in  this  relation  the  wool  may  be  said  to 


CHEMISTRY  OF   MORDANTING 


343 


possess  a  basic  character;  but  it  also  possesses  an  acid  character  in  that  it 
can  combine  with  bases.  In  appljdng  these  principles  to  the  action  of  a 
boiling  dilute  solution  of  aluminium  sulphate  on  wool  we  have  the  follow- 
ing as  a  suggested  explanation  of  what  takes  place:  in  a  boiling  dilute  solu- 
tion of  aluminium  sulphate,  in  the  first  place,  a  certain  amount  of  disso- 
ciation of  the  salt  occurs,  so  that  there  exists  already  in  the  solution  some 
free  acid  and  some  of  the  basic  salt.  The  wool  combines  with  this  free 
acid,  on  the  one  hand,  and  with  the  basic  salt  (or  with  the  hydrate  if  the 
dissociation  has  gone  far  enough)  on  the  other  hand.  The  alumina  which 
is  thus  taken  up  by  the  fiber  is  converted  into  an  insoluble  form.  Under 
certain  conditions,  no  doubt,  the  basic  salts  themselves  are  absorbed  by 
the  fiber  as  such;    and  these  apparently  undergo  further  decomposition 


Fig.  178. — Machine  for  Boiling,  Mordanting  or  Dyeing  Cloth  in  Open  Width. 

(Zittauer.) 

when  washed  with  water,  as  acid  is  removed  and  the  compound  becomes 
more  basic. 

Under  these  circumstances  it  would  perhaps  be  thought  that  the  basic 
salts  would  be  eminently  adapted  to  use  as  mordants;  but  it  seems  that 
in  the  case  of  the  aluminium  compounds  at  least,  the  basic  salts  too  readily 
dissociate  with  the  formation  of  fine  precipitates,  and  this  precipitation 
takes  place  in  the  mordanting  bath  before  the  wool  fiber  has  thoroughly 
absorbed  the  salt,  with  the  result  that  there  is  a  considerable  amount  of 
precipitated  mordant  attached  to  the  outer  layers  and  interstices  of  the 
fiber  as  a  superficial  deposit  which  is  rather  easily  removed  by  washing  or 
rubbing.  On  this  account  it  will  be  seen  that  it  is  not  desirable  to  employ 
a  salt  for  mordanting  which  dissociates  too  readily,  and,  in  fact,  in  prac- 
tice, it  is  usually  found  to  be  necessary  to  employ  some  agent  which  will 
retard  this  dissociation  so  that  the  substance  of  the  fiber  may  first  become 


344  APPLICATION  OF  MORDANT  DYES 

thoroughly  impregnated  with  the  salt  before  any  insoluble  compound  is 
formed. 

The  principal  metals,  the  salts  of  which  are  employed  for  the  mordant- 
ing of  wool  are  chromium,  aluminium,  copper,  and  iron.  The  first  two  are 
the  most  extensively  used  and  the  latter  two  are  of  onlyminor  importance  in 
this  connection.  Tin  salts  are  also  sometimes  employed  in  conjunction  with 
certain  dyes,  such  as  Cochineal.  The  chief  mordant,  however,  by  far,  is 
sodium  (or  potassium)  bichromate,  more  commonly  known  in  the  dyehouse 
as  "  chrome."  This  is  the  mordant  used  for  dyeing  practically  all  of  the 
alizarine,  mordant,  and  acid-mrrdant  or  after-chromed  dyes;  it  is  also 
the  principal  mordant  used  in  conjunction  with  the  natural  dyewoods. 

3.  Mordanting  with  Chrome. — At  the  present  time  the  salt  used  for 
this  method  of  mordanting  is  sodium  bichromate,  Na2Cr207.  Formerly 
potassium  bichromate  was  used  almost  entirely;  but  during  the  recent  war 
potassium  salts  were  very  scarce,  and  even  before  the  war  sodium  bichro- 
mate was  coming  into  vogue  as  a  mordant,  as  the  sodium  salt  was  cheaper 
than  the  potassium  salt.  In  former  times  the  potassium  salt  was  pre- 
ferred owing  to  the  fact  that  it  crystallized  nicely  and  could  thus  be  pre- 
pared very  pure  and  free  from  iron  (which  is  very  essential  in  its  use  as  a 
mordant  for  most  colors),  whereas  the  sodium  salt  was  difficult  to  obtain  in 
a  crystalline  condition,  and  furthermore  it  deliquesced  on  exposure  to  the 
air  and  became  pasty  and  hard  to  handle.  Modern  and  improved  methods 
of  manufacture,  however,  developed  a  crystalline  form  of  sodium  bichro- 
mate in  a  highly  purified  state  and  it  rapidly  displaced  the  potassium  salt. 

When  wool  is  boiled  in  a  solution  of  sodium  bichromate  alone  the  salt  is 
only  slightly  dissociated.  There  is,  however,  a  small  amount  of  chromium 
salt  fixed  in  the  fiber,  the  bichromate  apparently  being  reduced  to  a  certain 
degree  by  the  substance  of  the  wool  fiber  itself,  with  the  result  that  a  small 
proportion  of  chromium  hydrate  is  formed  and  taken  up  by  the  fiber.  To 
obtain  a  proper  degree  of  mordanting,  however,  it  is  necessary  to  add  some 
assisting  agent  to  the  solution  of  chrome.  These  assisting  agents  may  be  of 
various  kinds;  acids  such  as  sulphuric,  hydrochloric,  etc.,  may  be  used, 
also  various  organic  substances  such  as  cream  of  tartar,  lactic  acid,  etc. 
When  sulphuric  acid,  for  example,  is  added  to  a  solution  of  sodium  bichro- 
mate, a  corresponding  amount  of  chromic  acid  is  liberated;  this  is  readily 
taken  up  by  the  wool  fiber,  mostly  in  the  form  of  the  acid  chromium  oxide, 
though  a  small  amount  of  reduced  chromumi  oxide  is  also  present  (due 
to  the  reducing  action  of  the  organic  substance  of  the  fiber.  This  forms 
what  might  })e  called  an  oxidizing  mordant,  and  is  useful  in  cases  where  not 
only  the  mordanting  action  of  the  salt  is  needed  but  where  an  oxidizing 
effect  is  also  desired,  as  in  the  case  of  dyeing  wool  with  Logwood  extract. 

Usually,  however,  an  assistant  is  employed  which  exerts  a  reducing 
action  on  the  sodium  bichromate,  so  that  the  mordant  as  eventually 


MORDANTING  WITH  CHROME  345 

obtained  on  the  fiber  consists  of  the  chromium  oxide  rather  than  the 
chromic  acid  oxide.  In  this  connection  it  may  be  well  to  call  attention  to 
the  fact  that  chromium  is  a  metal  which  is  capable  of  forming  two  oxides, 
the  one  Cr203,  is  known  as  chromium  oxide  and  forms  salts  with  acids,  so 
that  the  metal  acts  as  a  base.  On  the  other  hand,  chromium  also  forms  the 
oxide  CrOa,  known  as  the  oxide  of  chromic  acid  because  this  oxide  forms 
salts  with  bases  (such  as  sodium  and  potassium)  and,  therefore,  the  metal 
acts  as  an  acid.  Sodium  bichromate  is  a  derivative  of  the  acid  oxide,  and 
both  chromic  acid  and  its  salts  are  yellow  in  color  (at  least  when  in  solu- 
tion). Chrome  alum  or  chromium  sulphate,  for  instance,  are  salts  ,of 
chromium  oxide,  the  base,  and  both  the  salts  and  the  base  are  green  in 
color.  Generally  speaking,  when  wool  is  mordanted  with  chrome  it  is  the 
green  basic  chromium  compound  that  is  desired  as  the  mordant  on  the 
fiber,  so  it  will  be  seen  that  it  is  necessary  to  reduce  the  acid  chrome  to  the 
basic  chromium  compound.  It  is  spoken  of  as  a  reducing  action  because 
it  is  converting  a  compound  derived  from  a  higher  oxide  (CrOs)  to  one 
derived  from  a  lower  oxide  (Cr203).  The  reduction  of  salts  of  chromic 
acid  to  those  of  chromium  oxide  takes  place  rather  readily  in  the  presence 
of  many  organic  substances,  the  latter  themselves  being  oxidized.  Cer- 
tain inorganic  reducing  agents  may  be  emploj^ed  also,  such  as  sodium 
bisulphite  (in  the  Amend  mordanting  process)  .*  Chrome  alum  or  chromium 
sulphate  may  also  be  used  directly,  but  these  do  not  seem  to  give  as  satis- 
factory a  mordanting  as  when  chrome  is  employed.  The  chief  idea  in 
mordanting  is  to  obtain  a  maximum  amount  of  chromium  oxide  (Cr203) 
fixed  in  the  fiber  for  a  minimum  amount  of  the  salt  used  in  the  process; 
also  the  absorption  of  the  mordant  must  be  uniform  and  it  must  penetrate 
well  throughout  the  mass  of  the  fiber  substance  in  order  that  the  colors 
subsequently  dyed  may  be  satisfactory. 

Practical  experience  seems  to  indicate  that  the  most  satisfactory 
assistant  for  use  in  mordanting  wool  with  chrome  is  cream  of  tartar. 
Owing  to  the  rather  high  cost  of  this  material,  however,  many  other  mate- 
rials have  been  used.  Some  of  these  are  oxalic  acid,  lactic  acid,  lactolire 
(sodium  lactate),  lignorosin  (a  substance  obtained  from  the  waste  sulphite 
liquors  in  the  preparation  of  paper  pulp) ,  and  many  others.  Even  sodium 
bisulphate  has  been  used  as  a  tartar  substitute,  but  in  this  case  the  effect 
would  be  the  same  as  using  a  corresponding  amount  of  sulphuric  acid,  and 
only  an  oxidizing  mordant  would  be  obtained  unless  some  reducing  medium 
was  also  employed  in  connection  with  the  bisulphate. 

*  Amend's  process  of  mordanting  is  as  follows:  first  mordant  the  wool  for  ten  min- 
utes with  1  per  cent  chromic  acid;  then  add  3  per  cent  sulphuric  acid  and  work  for  one- 
half  hour  cold;  add  8  to  10  per  cent  sodium  bisulphite  (52°  Tw.)  and  work  cold  for 
three-quarters  of  an  hour;  run  off  the  liquor  and  treat  in  a  fresh  bath  containing  5  per 
cent  soda  ash,  warming  to  130°  F.  for  one-half  hour  then  rinse  well.  This  method  is 
obsolete  on  account  of  its  complexity. 


346 


APPLICATION  OF  MORDANT  DYES 


The  selection  of  the  assisting  agent  will  depend  somewhat  on  the  nature 
of  the  dyeing  and  the  dj'estuff  to  be  used.*  In  the  dyeing  of  dark  blue, 
blacks,  and  other  heavy  shades  with  the  alizarines,  it  is  found  that  lactic 
acid  is  quite  satisfactory,  while  with  light  shades  and  bright  tones  the 
proper  effect  is  only  obtained  with  tartar;  although  this  latter  assistant  is 
in  general  the  highest  in  cost  of  all  those  employed. 

In  the  practical  application  of  the  mordanting  operation  it  is  customary 
to  boil  the  woolen  material  (which  may  be  either  in  the  form  of  yarn  or 
woven  cloth)  for  one  and  one-half  to  two  hours  in  the  mordant  bath 
which  contains  the  necessary  quantity  of  chrome  and  the  reducmg  agent 


Fig.  179. — Open  Width  Crabbing  and  Dyeing  Machine.     (Zittauer.) 


which  may  have  been  selected.  The  color  of  the  mordant  liquor  at  first  is 
golden  yellow,  but  it  gradually  changes  to  a  greenish  tone,  and  the  wool 
itself  also  acquires  a  greenish  color.  The  best  results  in  subsequent 
dyeing  are  said  to  be  obtained  if  the  goods  after  boiling  are  allowed  to 
remain  in  the  warm  bath  overnight,  and  this  rule  is  good  for  all  mordants 
except  that  of  tin.  After  coming  from  the  mordant  bath  the  goods  should 
be  well  washed,  and  they  are  then  ready  for  the  dyeing  operation. 

*  The  exact  method  of  chroming  to  be  adopted  can  be  determined  only  from  a 
knowledge  of  the  particular  dyestuff  to  be  used.  For  example,  Brilliant  Alizarine  Blue 
R  will  give  the  best  result  when  dyed  on  a  mordant  of  chrome  and  oxalic  acid;  Gallo- 
cyanine  gives  colors  much  faster  to  rubbing  on  a  mordant  of  chrome  and  tartar  than  on  a 
mordant  of  chrome  and  sulphuric,  oxalic,  or  formic  acids.  On  the  other  hand,  Aliz- 
arine Brown  M  must  be  dyed  on  a  mordant  of  chrome  and  acid,  as  the  shades  on  chrome 
and  tartar  are  not  fast  to  fulling. 


ASSISTANTS  USED  IN  MORDANTING  347 

In  mordanting  wool  with  chrome  the  mordanting  bath  is  not  exhausted 
and  may  be  used  again  for  fresh  lots  of  wool,  adding  about  2  per  cent  of 
chrome  and  3  per  cent  of  tartar  each  time.*  After  mordanting  the  wool 
should  be  well  washed  in  order  to  remove  the  excess  of  mordanting  liquor 
from  the  fiber,  which  coming  in  contact  with  the  dye  liquor  would  cause  a 
loss  of  coloring  matter  by  precipitation  and  also  form  a  loosely  adherent 
surface  color-lake  on  the  fiber  which  would  eventually  rub  off  badly  and 
cause  the  color  to  smut  or  crock.  It  has  been  demonstrated  that  about 
3  per  cent  of  chrome  is  the  proper  amount  of  mordant  to  employ  for  full 
shades  of  alizarine  colors;  for  lighter  shades  less  mordant  may  be  used. 
If  larger  quantities  than  3  per  cent  are  employed,  the  color  is  liable  to  be 
injured  and  will  not  be  as  heavy  or  as  bright  as  when  only  3  per  cent  is  used. 
The  use  of  too  much  chrome  also  has  the  effect  of  oxidizing  the  wool  fiber 
itself,  causing  it  to  become  harsh,  and  with  some  dyes  to  take  up  less  col- 
oring matter.  In  place  of  using  tartar  as  the  assistant  in  the  mordanting 
process,  there  may  be  employed  such  substances  as  those  mentioned 
above,  and  even  sulphuric  or  hydrochloric  acids  may  also  be  used,  and 
sodium  bisulphate  (which  is  sold  as  "  tartar  substitute  ")  is  frequently 
employed  where  cheapness  is  more  desirable  than  quality,  f  It  is  the  general 
opinion,  however,  that  tartar  furnishes  the  best  all-round  results.  Lactic 
acid  employed  in  connection  with  sulphuric  acid  is  a  very  good  assistant 
where  heavy  shades,  such  as  blues,  browns,  etc.,  are  to  be  dyed;  it  causes  a 
complete  reduction  and  exhaustion  of  the  mordanting  bath  and  only 
requires  the  use  of  about  2  per  cent  of  chrome  in  place  of  the  usual  3  per 
cent;  it  causes  the  mordanted  wool  to  have  a  very  decided  greenish  color, 
however,  and  on  this  account  does  not  give  as  good  results  as  tartar  in 
certain  shades.  The  use  of  formic  acid  as  a  chrome  assistant  is  becoming 
of  some  importance. 

4.  Mordanting  with  Other  Metallic  Salts. — In  mordanting  with  alum, 
the  mordant  employed  is  usually  potash  alum  rather  than  soda  alum,  as 
the  former  is  more  liable  to  be  free  from  impurities,  and  more  especially 
free  from  traces  of  iron,  which  would  exert  a  dulling  effect  in  the  subse- 
quent dyeing.  Of  recent  years  aluminium  sulphate  has  been  prepared 
commercially  in  a  high  degree  of  purity,  and  this  salt  is  now  being  exten- 

*  The  chrome  and  tartar  should  be  dissolved  and  added  separately  to  the  bath. 
t  When  substitutes  for  tartar  are  employed,  the  following  relative  proportions  may 
be  used: 

Sulphuric  acid 1  Ho  2  per  cent 

Oxalic  acid 1  Ho  2  per  cent 

Lactoline 1  Ho  2  per  cent 

Formic  acid 2    to  4  per  cent 

Lactic  acid 5  per  cent 

Sulphuric  acid 1  per  cent 


348 


APPLICATION  OF  MORDANT  DYES 


sively  used  for  mordant  purposes,  as  its  content  of  active  mordanting 
material  is  much  higher  than  is  the  case  with  alum,  as  the  latter  contains 
a  large  proportion  of  water  of  crystallization,  and  also  contains  a  consid- 
erable amount  of  inert  potassium  sulphate.  In  using  either  alum  or  alumi- 
nium sulphate  the  customary  and  the  best  assistant  to  employ  is  tartar. 
In  this  case,  however,  the  tartar  does  not  act  as  a  reducing  agent  on  the 
mordanting  salt,  but  serves  as  a  means  of  bringing  about  a  more  ready 
dissociation  of  the  salt  so  that  more  of  the  aluminium  hydrate  may  be 
taken  up  by  the  fiber.     It  is  usual  to  boil  the  wool  in  the  mordant  bath  for 


Fig.  180. — Machine  for  Mordanting  Cotton  Yarn.     (Timmer.) 


one  and  one-half  to  two  hours  in  a  manner  similar  to  that  of  mordanting 
with  chrome.  Apparently  if  the  mordanting  takes  place  without  the 
addition  of  tartar  to  the  bath,  the  aluminium  compound  taken  up  by  the 
fiber  (either  in  the  form  of  a  hydrate  or  a  basic  sulphate)  is  not  in  a  satis- 
factory condition  to  form  a  good  color-lake  with  the  dj^estuff .  Oxalic  acid 
or  lactic  acid  may  also  be  emploj^ed  in  place  of  tartar  and  at  a  more 
reasonable  cost,  but  the  results  in  dyeing  do  not,  as  a  rule,  appear  to  be 
as  good.  The  influence  of  the  tartar  in  the  mordanting  with  aluminium 
compounds  is  perhaps  more  in  the  way  of  affecting  the  physical  condition 
of  the  absorbed  aluminium  hydrate  or  oxide  rather  than  chemically 
influencing  the  reaction,  and  it  is  well  known  in  the  preparation  of  color- 
lakes  (irrespective  of  the  fiber)  that  the  physical  condition  of  the  base  on 


METHODS  OF  MORDANTING  349 

which  the  color  is  precipitated  has  much  to  do  with  the  satisfactory 
nature  of  the  finished  color-lake. 

Mordanting  wool  with  iron  or  tin  compounds  is  seldom  done  in  general 
practice.  For  the  production  of  an  iron  mordant  ferrous  sulphate  (cop- 
peras) is  generally  employed,  the  wool  being  boiled  in  the  mordanting  bath 
with  the  addition  of  an  equal  amount  of  oxalic  acid.  If  tartar  is  used  in 
this  case  there  will  be  precipitated  in  the  wool  a  basic  sulphate  of  iron  and 
the  fiber  will  exhibit  a  rusty-brown  appearance;  whereas  by  the  use  of 
oxalic  acid  no  precipitation  takes  place,  and  the  wool  acquires  a  nice  creamy 
color. 

For  mordanting  with  tin  it  is  customary  to  employ  stannous  chloride 
or  tin  crystals  with  the  addition  of  tartar,  and  boiling  the  wool  as  usual 
in  the  mordant  bath  for  one  and  one-half  to  two  hours.  It  is  not  advis- 
able to  allow  the  wool  to  steep  in  the  mordant  bath,  as  the  fiber  is  liable 
to  become  harsh  and  tendered. 

5.  Description  of  Mordanting  Methods. — The  following  is  a  brief  sum- 
mary and  description  of  the  principal  methods  employed  in  mordanting 
wool  in  practice. 

(a)  Chrome  Mordant. — In  this  case  chrome  alone  is  used  without  any 
assistant,  and  this  is  perhaps  the  method  of  mordanting  most  commonly 
employed  by  dyers.  The  wool  is  simply  boiled  for  one  to  two  hours  in  a 
bath  containing  2  to  4  per  cent  of  chrome.  A  standing  bath  may  be 
maintained,  being  freshened  up  each  time  by  the  addition  of  about  three- 
fourths  of  the  original  amount  of  chrome.* 

(b)  Chrome  and  Tartar  Mordant. — Use  3  per  cent  (on  the  weight 
of  the  wool)  of  chrome  as  sodium  bichromate.  This  should  be  well  dis- 
solved in  the  mordant  bath,  which  should  be  at  about  160°  F.  Enter  the 
wool,  which  should  be  well  scoured  and  washed,  and  bring  to  the  boil 
for  one-half  hour.  Then  add  3  per  cent  of  tartar  dissolved  in  hot  water, 
stir  up  well  and  boil  for  one  to  one  and  one-half  hours  longer.  Where  hard 
water  is  used  it  is  best  to  add  a  small  amount  of  acetic  acid.  In  the  case 
of  light  shades  being  dyed  the  quantity  of  chrome  and  tartar  may  be 
correspondingly  diminished.  By  allowing  the  goods  after  boiling  to  steep 
for  some  time  in  the  warm  mordant  bath  the  intensity  of  the  mordanting 
may  be  somewhat  increased. 

(c)  Chrome  and  Formic  Acid. — This  acid  is  being  more  and  more  used 
as  a  chrome  assistant,  as  it  gives  very  good  results,  and  practically  ex- 
hausts the  bath,  and  consequently  less  chrome  is  required.  Prepare  the 
bath  with  1  to  2  per  cent  of  chrome  and  1  to  2  per  cent  of  formic  acid 

*  It  is  claimed  by  dyers,  in  fact,  that  old  mordanting  baths  of  chrome  give  better 
results  in  dyeing  than  when  fresh  baths  are  used ;  this  is  perhaps  due  to  the  partial  reduc- 
tion of  the  chrome  and  the  presence  of  accumulated  colloidal  substances  which  may  aid 
in  the  mordanting. 


350 


APPLICATION  OF  MORDANT  DYES 


(80  per  cent).  The  disadvantage  of  this  method  is  that  the  reduction  of 
the  chrome  takes  place  too  rapidly  and  uneven  mordanting  is  liable  to 
result  which  will  show  up  in  uneven  dyeings.  It  is  best,  therefore,  to  start 
the  bath  at  140°  F.  and  graduallj'  bring  up  to  the  boil,  and  then  boil  for 
about  one  and  one-half  hours. 

(d)  Chrome  and  Sulphuric  Acid. — This  method  is  employed  when  an 
oxidizing  mordant  is  desired,  especially  when  dyeing  Logwood.  The  mor- 
dant obtained  on  the  wool  is  of  a  yellow  color,  and  probably  consists  of  a 
chromate  of  chromium  which  is  capable  of  exerting  a  rather  strong  oxidiz- 
ing action  on  the  dye.  Other  chrome  mordants  give  a  greenish  color  to 
the  mordanted  wool,  as  the  mordant  on  the  fiber  consists  of  chromium 
hydrate  or  oxide  and  retains  no  oxidizing  power.  Prepare  the  bath  with 
3  per  cent  of  chrome  and  1  per  cent  of  sulphuric  acid  and  boil  the  wool 


Fig.  181. — Yarn  Mordanting  Machine.     (Dehaitre.) 

for  one  to  two  hours.  After  treating  with  this  mordant  the  wool  should  not 
be  exposed  long  to  light,  as  this  will  cause  reduction  of  the  chrome  to 
the  green  chromium  oxide,  and  may  give  rise  to  streaky  colors  in  dyeing. 

(e)  Chrome  and  Lactic  Acid  Mordant. — This  process  is  carried  out  in 
practically  the  same  manner  as  the  preceding,  only  in  this  case  2|  per  cent 
of  chrome  and  5  per  cent  of  lactic  acid  are  used.  The  lactic  acid  which  is 
commercially  available  is  usually  of  50  per  cent  strength,  and  comes  in  the 
form  of  a  liquid.  The  amount  referred  to  in  this  process  is  based  on  the 
commercial  variety. 

(f)  Another  Chrome  and  Lactic  Acid  Mordant. — The  mordant  bath  is 
made  up  with  the  required  quantity  of  water,  heated  to  160°  F.,  and 
then  the  following  mordant  materials  are  added  in  their  respective  order : 
2^  per  cent  of  chrome,  Ij  per  cent  of  sulphuric  acid  (66°  Be.),  and  3  per 
cent  of  lactic  acid ;  stir  up  the  bath  well,  enter  the  wool  and  work  for  one- 
half  hour  at  160°  F.,  bring  up  to  the  boil  within  half  an  hour  and  finally 


i 


METHODS  OF   MORDANTING  351 

boil  for  one  hour.  Under  these  conditions  the  bath  becomes  almost  com- 
pletely exhausted,  and,  therefore,  may  be  considered  as  somewhat  of  an 
improvement  over  the  preceding  process,  and  fm*thermore  less  lactic  acid 
is  required. 

(g)  Chrome  and  Oxalic  Acid  Mordant. — Prepare  the  mordant  bath 
with  3  per  cent  of  chrome  and  3  per  cent  of  oxalic  acid.  Carry  out  the 
treatment  as  in  process  (a).  By  the  further  addition  of  ^  to  1  per  cent  of 
sulphuric  acid  it  is  possible  to  obtain  a  better  exhaustion  of  the  bath. 
This  method  of  mordanting  is  somewhat  cheaper  than  the  chrome  and 
tartar  method,  and  in  certain  dyeings  gives  brighter  shades  than  the  latter. 

(h)  Chromium  Fluoride  Mordant. — In  this  case  the  mordant  bath  is 
prepared  with  4  per  cent  of  chromium  fluoride  and  1  per  cent  of  oxalic 
acid,  and  the  wool  is  treated  at  the  boil  for  one  hour. 

(i)  Alum  Mordant. — The  mordant  bath  is  made  up  with  5  per  cent 
of  iron-free  alum  (or  3  per  cent  of  pure  aluminium  sulphate)  and  5  per  cent 
of  tartar  (or  2 J  per  cent  of  oxalic  acid) .  The  two  salts  should  first  be  well 
dissolved  in  warm  water  and  then  added  to  the  bath,  which  is  heated  to  a 
temperature  of  about  160°  F,  The  wool  is  then  entered,  the  bath  is  brought 
up  to  the  boil  within  half  an  hour,  and  the  boihng  is  continued  for  an  hour 
longer. 

(j)  Iron  Mordant. — ^The  bath  is  prepared  in  the  following  manner: 
dissolve  in  the  warm  bath  5  per  cent  of  oxalic  acid;  then  dissolve  in  some 
very  soft  cold  water  5  per  cent  of  ferrous  sulphate  (copperas).  Add  this 
latter  solution  to  the  oxalic  acid  bath  with  constant  stirring,  and  when  the 
bath  has  become  clear  and  colorless,  introduce  the  wool,  and  boil  for  one 
and  one-half  hours.  After  mordanting  the  wool  should  be  almost  white 
or  only  show  a  creamy  color,  and  in  no  case  should  be  brown, 

(k)  Tin  Mordant. — In  the  preparation  of  this  bath  use  the  following 
ingredients:  4  per  cent  stannous  chloride  and  5  per  cent  of  tartar;  treat 
the  wool  for  one  hour  at  190°  F.,  taking  care  not  to  bring  the  bath  to  the 
boil.  After  one  hour  remove  from  the  bath  and  wash  very  well,  and  under 
no  circumstances  leave  the  wool  lying  in  the  bath. 

6.  Single-bath  Methods  of  Mordanting. — In  former  days  the  mor- 
dants were  nearly  always  applied  in  a  separate  bath  from  that  of  the  dyeing 
operation ;  or,  at  least,  the  mordant  was  applied  first,  and  if  the  bath  was 
completely  exhausted,  the  same  bath  could  then  be  employed  as  the  dye- 
bath.  This  was  especially  true  in  cases  of  dyeing  where  the  natural 
dye  woods  were  employed  and  where  the  old-line  alizarines  were  used.  The 
use  of  two  baths  was  almost  essential  to  obtain  a  satisfactory  dyeing.  In 
later  years,  however,  a  number  of  the  coal-tar  dyes  were  found  to  be  of 
such  a  nature  that  the  mordant  and  the  dyestuff  could  be  applied  in  one 
bath  by  first  dyeing  the  wool  with  the  coloring  matter  in  an  ordinary  acid 
bath  (using  generally  acetic  acid,  though  sometimes  sulphuric  acid  was  also 


352 


APPLICATION  OF  MORDANT  DYES 


added  later  to  obtain  as  complete  exliaustion  as  possible)  and  then  adding 
the  mordant  (which  was  nearly  always  chrome)  and  boiling  the  material 
for  about  one-half  hour  longer.  This  one-bath,  or  after-chroming,  method 
was  of  course  only  applicable  to  dyestuffs  which  were  capable  of  being  taken 
up  by  the  wool  in  a  neutral  or  acid  bath.  In  fact,  these  dyes  (which  were 
generally  certain  sulphonated  alizarine  dyes  or  certain  azo  acid  dyes) 
really  dyed  the  wool  like  an  acid  color,  but  the  dyeing  so  obtained  was  not 
particularly  fast.  By  after-mordanting,  however,  a  true  mordant  color- 
lake  was  produced  which  had  very  satisfactory  fastness. 

In  more  recent  years  it  was  also  discovered  that  certain  of  these  acid 
mordant  dyes  could  be  used  in  a  single  bath  simultaneously  with  the  mor- 
dant if  certain  precautions  were  observed  in  the  process.     In  this  case  the 


Fig.  182. — Jigger  for  Oiling,  Mordanting  and  Dyeing  Cotton  Cloth.     (Dehaitre.) 


dyestuff  solution  is  added  to  the  bath  together  with  the  chrome,  also  using 
some  ammonium  sulphate  or  acetate  and  keeping  the  bath  well  under  the 
boil  for  some  time.  This  process  was  known  as  the  "  meta-chrome," 
"  chromate,"  or  "  mono-chrome  "  method,  and  was  very  largely  used  on 
account  of  the  great  saving  in  handling  and  time  as  well  the  use  of  less 
machinery  and  materials.  In  this  process  the  dyeing  and  the  mordanting 
may  be  said  to  take  place  simultaneously,  and  the  mordant  is  prevented 
from  precipitating  the  dyestuff  as  a  color-lake  in  the  bath  by  the  presence 
of  the  ammonium  salt.  The  dye  and  the  mordant  are  taken  up  by  the 
fiber  simultaneously,  but  the  color-lake  or  insoluble  dye-mordant  com- 
pound is  only  produced  when  the  bath  is  finally  brought  to  the  boil  and 
the  ammonium  salts  are  dissociated  and  driven  off. 

7.  Dyeing  with  Mordant  Colors. — In  dyeing  wool  with  the  mordant 
colors  it  is  particularly  important  that  the  material  be  thoroughly  scoured 


PREPARATION  OFDYEBATH  353 

free  from  greasy  substances,  and  that  the  soapy  residues  be  very  completely 
removed  by  rinsing.  If  this  is  not  done  sticky  insoluble  metallic  com- 
pounds will  be  formed  with  the  mordant  employed  and  these  will  enter 
into  the  formation  of  the  color-lakes  eventually  dyed  with  the  result  that 
the  color  may  appear  streaky  or  spotty  and  exhibit  the  bad  defect  of 
rubbing.  Wool  is  very  largely  dyed  with  the  mordant  colors  in  the  loose 
stock  for  the  production  of  yarns  entering  into  fabrics  which  are  after- 
wards more  or  less  heavily  fulled  (or  felted),  so  that  these  dyes  are  more 
used  for  woolen  goods  than  for  worsteds  (which  require  no  fulling) .  It  is 
essential,  therefore,  that  the  mordanting  and  dyeing  operations  should 
be  so  conducted  as  to  injure  the  fiber  to  the  least  extent,  otherwise  great 
waste  will  occur  in  the  carding  and  spinning  operations.  Also  precautions 
must  be  had  not  to  make  the  fiber  harsh  or  brittle  in  the  mordanting. 

As  in  dyeing  with  mordant  colors  it  is  usually  necessary  to  boil  the 
material  in  the  dyebath  rather  vigorously  and  for  a  long  period,  it  is  best 
to  use  suitable  dyeing  machines  that  require  a  minimum  mechanical 
treatment  of  the  fibers;  it  is  preferable  to  circulate  the  liquors  through  the 
fiber,  while  maintaining  the  latter  at  rest  in  a  fixed  position. 

Calcium  acetate  is  frequently  added  to  the  dyebath  for  the  purpose  of 
brightening  the  color,  and  it  is  supposed  that  a  triple  color-lake  is  formed 
between  the  chromium,  the  calcium,  and  the  alizarine.  Where  the  water 
employed  for  the  dyebath  is  sufficiently  hard  (that  is,  contains  sufficient 
lime  salts  in  solution)  the  addition  of  acetic  acid  in  requisite  amounts  will 
form  the  neeessary  calcium  acetate,  hence  none  of  this  salt  need  be  added 
under  such  conditions.  For  water  of  5  to  10°  of  hardness  (one  degree  of 
hardness  represents  1  part  of  lime  in  100,000  parts  of  water)  2  parts 
acetic  acid  (of  9°  Be.)  should  be  added  for  each  1000  parts  of  water  in  the 
dyebath;  and  for  water  of  10  to  15°  hardness  3  parts  of  acetic  acid  should 
be  added.*  The  best  and  most  practical  way,  perhaps,  is  to  add  acetic 
acid  to  the  dyebath  until  a  test-paper  of  blue  litmus  is  distinctly  reddened. 
Acetic  acid  is  furthermore  added  to  the  dyebath  for  the  purpose  of  more 
thoroughly  exhausting  the  coloring  matter,  but  the  addition  of  the  acid  in 
this  case  should  not  be  made  until  near  the  end  of  the  dyeing  operation,  in 
order  to  prevent  unevenness. 

When  dyeing  piece-goods,  hat  felts,  or  such  material  that  is  difficult  to 
penetrate,  it  is  advisable  not  to  use  acetic  acid  at  the  beginning  of  the 
dyeing  operation,  but  to  add  about  3  gallons  of  ammonium  acetate  solu- 
tion per  1000  gallons  of  dye  liquor.  After  boiling  for  an  hour  the  acetic 
acid  may  be  added  to  further  the  exhaustion  of  the  dyebath. 

The  alizarines,  as  a  rule,  exhaust  quite  well  and  many  of  them  will  not 
require  the  addition  of  any  acid,  especially  when  light  shades  are  dyed. 

*  From  1  to  3  gallons  of  acetic  acid  (9°  Tw.)  will  be  required  per  1000  gallons  of  dye 
liquor. 


354 


APPLICATION  OF  MORDANT  DYES 


The  initial  temperature  of  the  alizarine  dyebath  should  be  quite  low  (100° 
F.  or  even  lower),  and  the  elevation  of  the  temperature  to  the  boil  should  be 
gradual  in  order  to  have  the  dyeing  even  and  well  penetrated.*  The  color- 
lake  does  not  develop  fully  until  after  boiling  for  some  time,  hence  it 
requires  a  longer  time,  as  a  rule,  to  dye  alizarines  than  it  does  acid  colors  on 
wool. 

When  dark  colors  are  dyed  with  the  alizarines  the  fastness  to  fulling 
may  be  materially  increased  by  the  addition  of  about  |  per  cent  of  chrome 
after  dyeing,  and  continuing  the  boiling  for  one-half  hour  longer. 

8.  Top-chrome  Method. — In  this  process  of  dyeing  mordant  colors  the 
dyestuff  is  first  applied  to  the  fiber  and  then  the  mordant  is  added  either 
in  the  same  bath  as  the  dyestuff  or  in  a  separate  bath.     The  method  of 


Fui.  183. — Jiggers  for  Mordanting  and  Dyeing.     (Zittauer.) 


simply  adding  the  mordant  to  the  same  l)ath  is  coming  more  and  more  into 
vogue  as  this  cuts  down  the  handling  of  the  goods  and  decreases  the  expense. 
In  using  this  process,  of  course,  it  is  necessary  to  employ  dyestuffs  that  are 
taken  up  by  the  wool  from  an  acid  bath  with  good  exhaustion  so  that  when 
the  chrome  mordant  is  added  there  is  little  or  no  dye  left  in  the  bath,  as 
otherwise  a  lake  would  be  precipitated  by  the  chrome  combining  with  the 
excess  of  dyestuff.  While  this  method  has  advantages  of  simplicity  and 
cost  there  are  difficulties  in  matching  to  shade  and  also  the  range  of  dye- 
stuffs  that  are  applicable  is  somewhat  limited.  The  true  alizarine  dyes 
cannot  be  employed  by  this  method,  as  a  rule,  as  these  will  only  be  taken 

*  When  the  sokible  powdered  alizarines  (the  bisulphite  compounds)  are  used  the 
temperature  of  the  dyebath  should  not  be  raised  above  150°  F.  until  practically  all  of 
the  color  has  been  absorbed,  as  at  higher  temi)eratures  the  bisulphite  compound  of  the 
dye  splits  up  and  allows  the  insoluble  dyestuff  to  be  precipitated  in  the  liquor.  This 
causes  loss  of  dyestuff  and  also  gives  colors  which  will  rub  badly. 


TOP-CHROME  METHOD  355 

up  by  the  fiber  when  a  mordant  is  already  present.  It  is  also  more  diffi- 
cult to  obtain  level  dyeing  with  the  top-chrome  method,  especially  on  yarns 
and  piece-goods.  The  method,  however,  is  well  adapted  to  the  dyeing  of 
loose  wool  and  slubbing  where  perfect  level  dyeing  is  not  required,  as  any 
lack  of  uniformity  is  corrected  by  the  mixing  of  the  fibers  in  drawing  and 
spinning.  The  method  is  also  largely  used  for  the  dyeing  of  blacks  and 
blues  and  heavy  shades  of  brown,  where  the  acid-chrome  dyes  are  used. 
In  the  case  of  loose  wool  and  slubbing  the  material  is  left  in  a  better  con- 
dition for  spinning  than  when  the  pre-mordanting  method  is  used,  and  as 
regards  fastness  it  may  be  said  that  in  many  cases  this  is  even  better  than 
by  the  older  process,  as  the  after-mordanting  tends  more  thoroughly  to  fix 
the  dyestuff  and  does  not  leave  any  excess  of  unfixed  dye  to  rub  or  wash  off. 

In  applying  this  process  the  dyestuff  is  first  well  boiled  up  with  a  small 
amount  of  water  in  the  dyevat,*  then  the  bath  is  made  up  with  cold  water 
and  1  to  5  per  cent  of  acetic  acid;  the  goods  are  entered  and  the  tempera- 
ture of  the  bath  is  gradually  raised  to  the  boil  and  maintained  at  that  tem- 
perature for  one  hour.  In  case  the  bath  is  not  completely  exhausted 
about  I  to  1  per  cent  of  sulphuric  acid  is  added  and  the  boiling  is  con- 
tinued until  the  liquor  is  clear.  Then  from  ^  to  2  per  cent  (depending  on 
the  amount  of  dyestuff  used)  of  chrome  is  added,  and  the  boiling  continued 
for  one-half  hour,  f  After  dyeing  the  wool  should  be  washed  off  immediately 
to  prevent  change  of  color  due  to  the  prolonged  action  of  the  chrome 
liquor. 

In  dyeing  piece-goods  or  yarns  by  this  process  it  is  not  advisable  to  add 
all  of  the  acid  at  once,  but  to  add  it  in  portions  until  the  bath  is  exhausted.  J 
Where  the  goods  contain  white  cotton  effect-threads  it  is  necessary  to  use 

*  To  obtain  the  best  results  with  some  of  the  after-chromed  colors  it  is  recommended 
to  correct  the  water  used  in  the  dyebath  by  the  addition  of  ammonium  oxalate.  For  100 
gallons  of  dye  liquor  the  following  amounts  of  this  salt  will  be  necessary: 

For  soft  water  (3  to  7°  hardness) 2    ozs. 

Moderately  hard  water  (7  to  10°) 5    ozs. 

Very  hard  water  (10  to  14°) 6    ozs. 

t  It  is  very  important  that  the  chrome  should  not  be  added  until  the  dyebath  is 
completely  exhausted  of  color,  as  otherwise  a  brownish  shade  will  nearly  always  result 
(m  the  dyeing  of  blacks).  The  tone  of  the  chrome  blacks  may  be  somewhat  regulated 
by  the  amounts  of  sulphuric  acid  and  chrome  used,  smaller  amounts  giving  bluish  tones 
and  larger  amounts  jet  shades.  In  dyeing  potting  chrome  blacks  it  is  best  to  use  2  to  3 
per  cent  of  sulphuric  acid  and  2  to  3  per  cent  of  chrome. 

t  In  cases  of  some  dyes  satisfactory  evenness  of  color  can  only  be  obtained  (espe- 
cially when  dyeing  piece-goods)  by  first  boiling  the  material  in  the  dyebath  with  addition 
of  acetic  acid  alone,  and  then  adding  the  dyestuff  solution.  When  dyeing  with  Chrome 
Blue  it  is  recommended  to  add  lactic  acid  (about  4  per  cent)  together  with  the  chrome, 
as  this  gives  increased  fastness  to  fulling.  With  some  dyes,  such  as  Palatine  Chrome 
Black  SR,  acetic  acid  only  can  be  used  in  dyeing. 


356  APPLICATION  OF  MORDANT  DYES 

more  sulphuric  acid  in  exhausting  the  bath  in  order  to  prevent  bleeding 
into  the  cotton. 

One  of  the  principal  uses  of  the  top-chrome  method  is  in  the  applica- 
tion of  the  so-called  "  chrome  blacks  "  to  wool.  Very  large  quantities  of 
these  blacks  are  used  in  the  dyeing  of  wool  for  the  production  of  shades 
that  are  especially  fast  to  washing,  light  and  fulling,  and  in  many  cases  to 
potting.  *  These  blacks  are  of  the  general  type  of  Diamond  Black,  of  which 
there  are  a  number  of  different  brands  on  the  market;  they  are  also  known 
as  Chrome  Black,  Anthracene  Chrome  Black,  Erio  Chrome  Black,  etc. 
Diamond  Black  F  is  a  very  good  example  of  this  class  of  colors,  and  it  has 
been  very  extensively  employed  on  wool  to  take  the  place  of  Logwood,  as  it 
is  very  fast  to  light  and  washing,  as  well  as  fulling.  It  is  not  fast  to  potting, 
however,  and  until  rather  recently  the  only  blacks  that  were  fast  in  this 
respect  were  Logwood  Black  and  Alizarine  Black.  Diamond  Black  PV  (the 
sufRx  "  P  "  meaning  fast  to  potting),  however,  will  stand  the  potting  test, 
and  on  this  account  is  a  very  important  dyestuff.  The  PV  brand  is  also 
much  more  soluble  than  the  others  and  requires  more  sulphuric  acid  and 
chrome  in  the  dyeing.  It  is  very  largely  used  for  the  dyeing  of  carbonized 
rags,  as  it  gives  a  well-penetrated  color.  The  chrome  blacks  do  not 
give  satisfactory  colors  when  dyed  by  the  pre-chrome  method,  nor  are 
the  results  very  good  with  the  meta-chrome  process. 

9.  Mono-chrome  or  Meta-chrome  Method. — In  this  process  of  dye- 
ing not  only  is  but  one  bath  employed,  but  the  dyestuff  and  the  chrome 
mordant  are  added  together,  so  that  the  mordanting  and  the  dyeing  take 
place  simultaneously.  Several  years  ago  this  process  was  used  with  the 
aid  of  a  special  "  meta-chrome  "  mordant  which  consisted  of  a  mixture 
of  potassium  chromate  and  ammonium  sulphate.  At  the  present  time 
the  dyer  usually  makes  up  his  own  meta-chrome  mordant.  This  process 
is  capable  of  being  used  with  a  large  number  of  the  mordant  dyes,  as  many 
of  these  are  not  precipitated  by  a  neutral  chromate.  On  the  other  hand, 
others  like  Gallocyanine  and  the  true  alizarines  cannot  be  used  in  this 
way,  as  even  the  neutral  chromate  will  cause  precipitation  of  the 
color-lake.  The  theory  of  the  meta-chrome  process  is  that  when  the  dye- 
bath  is  made  up  comparatively  cold  with  the  mixture  of  the  dyestuff  with 
chrome  and  an  ammonium  salt,  there  is  no  formation  of  the  color-lake; 
when  the  bath  is  heated,  however,  the  ammonium  salt  (which  is  no  doubt 

.  *  Potting  is  a  process  employed  for  giving  a  certain  character  of  finish  to  woolen 
cloth.  Briefly  described  it  consists  of  wrapping  the  goods  around  a  roller  and  immersing 
in  water  for  about  twenty-four  hours,  then  gigging.  These  operations  are  repeated 
several  times  until  the  desired  results  arc  obtained.  It  is  necessary  that  the  dyestuff 
employed  shall  not  bleed  into  adjacent  whites  or  colors.  The  potting  blacks  are  also 
serviceable  for  heavy  fulling  of  goods  having  mercerized  cotton-effect  threads,  as  the 
mercerized  cotton  will  become  more  or  less  stained  by  any  other  blacks. 


META-CHROME   METHOD 


357 


dissociated  in  the  bath)  is  decomposed  and  free  ammonia  is  driven  off, 
leaving  acid  in  the  bath.  Thus  the  conditions  become  such  as  to  cause  a 
precipitation  of  the  color-lake;  but  at  this  stage  the  dyestuff  has  been 
practically  all  absorbed  by  the  fiber,  so  that  the  formation  of  the  color- 
lake  takes  place  only  within  the  fiber.  This  process  has  come  into  large  use 
for  the  dyeing  of  all  manner  of  chrome  shades  on  wool  in  any  form  of  man- 
ufacture from  the  loose  stock  to  the  finished  cloth.  It  is  more  especially 
adapted  perhaps  to  the  dyeing  of  slubbing  and  yarns.  The  dyes,  however, 
must  be  properly  selected  with  the  limitations  of  the  method  in  view. 
Dyes  for  this  purpose  are  called  by  various  names,  such  as  Meta-chrome, 
Mono-chrome,  Chromate  Colors,  Auto-chrome,  etc.  This  process  has  a 
distinct  advantage  over  the  other  methods  of  applying  mordant  dyes  in 


Fig.  184. — Horizontal  Drying  Cans.     (Zittauer.) 


that  it  requires  only  a  single  bath,  and  as  the  shade  develops  gradually  it  is 
much  easier  for  the  dyer  to  match  his  colors  than  with  the  top-chrome  proc- 
ess where  the  exact  color  is  not  known  until  after  the  dye  has  all  been 
absorbed  and  the  chrome  is  added. 

The  meta-chrome  method  may  be  carried  out  as  follows:  First  add 
the  color  solution  to  the  bath  and  then  a  solution  containing  the  required 
amount  of  chrome  and  ammonium  sulphate  made  alkaline  with  ammonia. 
In  dyeing  yarns  enter  the  goods  at  140°  F.,  slowly  bring  up  to  the  boil  and 
dye  for  one  hour.  Loose  wool  or  slubbing  may  be  started  at  higher  tem- 
peratures. Ammonium  acetate  may  be  used  in  place  of  the  sulphate,  but 
it  is  doubtful  if  it  gives  as  good  results,  while  at  the  same  time  it  is  more 
expensive.  Or  the  chrome  may  be  used  alone  with  ammonia,  and  acetic 
acid  is  added  toward  the  end  of  the  dyeing  to  make  the  bath  acid.     Formic 


358  APPLICATION  OF  MORDANT  DYES 

acid  may  also  be  used  in  tlic  same  manner.*  The  amount  of  chrome 
taken  is  usually  half  the  weight  of  the  color  used,  though  this  may  vary 
somewhat  according  to  the  dye.  For  each  part  of  chrome  use  2|  parts  of 
ammonium  sulphate  (or  if  acids  are  employed  use  2|  parts  acetic  acid,  1 
part  of  formic  acid,  1  part  of  sulphuric  acid,  or  4  parts  of  niter  cake). 
Where  small  quantities  of  dyes  are  used  the  amount  of  chrome  taken 
should  not  be  less  than  1  per  cent. 

The  dyes  which  can  be  used  with  the  meta-chrome  process  include 
browns,  reds,  greens,  and  yellows.  There  are  as  yet  no  dark  blue  or  black 
dyes  which  are  suitable  for  this  process.  There  are  also  some  other  dj'cs 
than  the  mordant  colors  which  may  be  used  in  the  bath  for  shading  and 
which  will  stand  the  action  of  the  chrome.  Such  dyes,  for  instance,  are 
Sulphon  Cyanine,  Indocyaninc,  and  Patent  Blue. 

10.  Dyeing  on  Various  Mordants. — Where  very  bright  colors  are  desired 
as  with  reds,  blues,  and  yellows,  chrome  cannot  be  used  as  the  mordant, 
but  alum  or  stannous  chloride  may  be  employed.  Alum  is  used  to  quite 
an  extent  for  certain  shades,  but  as  the  colors  obtained  on  a  tin  mordant 
are  not  as  fast  and  as  the  tin  mordant  makes  the  wool  harsh  and  brittle, 
it  is  very  little  used  in  practice.  In  order  to  obtain  as  bright  and  clear 
colors  as  possible  with  the  alizarine  dyes,  it  is  necessary  that  the  water  and 
the  chemicals  employed  both  for  mordanting  and  dyeing  should  be  free 
from  any  trace  of  iron,  as  the  presence  of  this  metal  causes  a  saddening  of 
the  color. 

Other  metallic  mordants  than  chrome  may  also  be  employed  in  the 
same  manner  as  the  top-chroming  method.  Chromium  fluoride,  alum, 
copperas,  and  bluestone  may  be  employed,  and  either  the  single-bath  or 
two-bath  method  may  be  used,  the  first,  howev'cr,  always  being  preferable 
wherever  possible.  After-mordanting  with  chromium  fluoride  is  chiefly 
employed  for  the  dyeing  of  medium  to  dark  blue  colors  on  piece-goods  with 
the  use  of  the  Anthracene  Blues.  The  dyebath  is  prepared  with  20  per 
cent  of  glaubersalt,  4  per  cent  of  oxalic  acid  and  the  necessary  dyestuff. 
The  dyeing  is  first  run  cold  for  thirty  minutes,  then  brought  to  the  boil 
for  about  one  hour  The  solution  of  chromium  fluoride  (2  to  4  per  cent)  is 
then  added,  and  the  boiling  continued  for  about  thirty  minutes. 

After-mordanting  with  alum  is  occasionally  carried  out  in  the  dyeing  of 

*  Another  one-bath  dyeing  process  somewhat  resembHng  the  meta-chrome  process 
is  one  using  a  mordant  of  chrome  and  formic  acid  in  the  following  manner:  The  bath 
is  first  prepared  with  I5  per  cent  of  chrome  and  2  per  cent  of  formic  acid  (80  per  cent); 
run  the  goods  for  I2  hours  at  1G0°  F.,  then  add  the  well-dissolved  dyestuff  and  continue 
the  dyeing  for  one  hour;  finally  add  2  per  cent  more  of  formic  acid  and  gradually  bring 
to  the  boil.  This  method  depends  on  the  fact  that  the  use  of  formic  acid  completely 
exhausts  the  chrome  before  the  dye  is  added  and  therefore  no  precipitation  of  dye  takes 
place  in  the  bath.  This  process,  however,  has  not  proved  very  popular  and  no  doubt 
the  results  are  not  as  satisfactory  as  by  the  other  method. 


DYEING  ON  VARIOUS   MORDANTS 


359 


Ijright  reds.  The  acid-chrome  or  milHng  reds  are  used  and  the  dyeing  is 
done  as  above  described,  then  a  sohition  of  10  per  cent  of  alum  in  hot 
water  is  added,  and  the  dj^eing  continued  at  the  boil  for  one-half  hour. 
The  oxalic  acid  is  added  in  these  cases  of  after-mordanting  in  order  to  cor- 
rect the  hardness  of  the  water,  and  where  this  is  considerable  the  amount  of 
oxalic  acid  must  be  correspondingly  increased.  The  presence  of  copper 
surfaces  should  be  avoided  in  the  dyebath,  either  wooden  or  tinned  copper 
vessels  being  used.  The  Alizarine  Reds  and  Oranges  may  be  dyed  in  this 
manner. 

The  after-mordanting  with  copperas  (ferrous  sulphate)  is  principally 
employed  in  the  case  of  dyemg  black  where  Logwood  is  used  in  connection 


Fig.  185. — Dryer  and  Foulard. 

with  a  coal-tar  mordant  dyestuff.  Bluestone  is  usually  employed  in  con- 
junction with  the  iron  salt.  The  following  is  an  example  of  this  process: 
Dye  with  2^  per  cent  of  oxalic  acid,  3  per  cent  of  Palatine  Black  4B  and 
10  per  cent  of  Logwood  extract;  after  boiling  for  one  hour  add  8  per  cent 
of  copperas  and  2  per  cent  of  bluestone,  and  continue  boiling  for  one  hour. 
Quite  a  variety  of  dyes  may  be  used  in  this  manner  for  the  shading  of 
Logwood  Black,  such  as  Fast  Blue,  Alkali  Violet,  Acid  Violet,  and  Fast 
Green  SF. 

An  after-mordanting  with  bluestone  is  sometimes  given  for  the  purpose 
of  increasing  the  fastness  to  light  of  certain  dyes.  The  dyeing  is  done  in 
the  usual  manner  and  then  the  bluestone  is  added  to  the  bath  and  the 
boiling  is  continued  for  one-half  to  one  hour. 


360 


APPLICATION  OF  MORDANT  DYES 


11.  Experimental.     Exp.  133.  General  Method  of  Dyeing  Mordant  Colors. — The 

most  generally  used  mordant  for  wool  is  chrome  or  sodium  bichromate.  It  is  applied 
to  the  fiber  in  the  following  manner:  Prepare  a  bath  containing  3  per  cent  of  chrome 
and  4  per  cent  of  tartar;  enter  a  test  skein  of  woolen  yarn  at  140°  F.,  gradually  raise  to 
the  boil,  and  continue  at  that  temperature  for  one-half  hour;  wash  well,  and  then  dye  in  a 
fresh  bath  containing  2  per  cent  Alizarine  Blue  NG  and  4  per  cent  of  calcium  acetate; 
enter  at  100°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half 
hour;  then  add  2  per  cent  of  acetic  acid  and  boil  for  fifteen  miimtes  longer;  wash  well 
and  dry.  Sodium  (or  potassium)  bichromate,  is  a  salt  of  chromic  acid  (CrO.^),  while  the 
mordant  which  is  eventually  produced  on  the  fiber  is  chromium  oxide  (Cr203) ;  hence  in 
the  process  of  mordanting  the  chrome  must  undergo  reduction.  This  is  brought  about 
partly  by  the  wool  itself,  but  chiefly  by  the  aid  of  the  tartar.     The  latter  is  potassium 


Fig.  186. — Dryer  for  Mordanted  Yarn. 

acid  tartrate,  or  potassium  bitartratc,  and  is  a  reducing  agent.  When  mordanting  it  will 
be  noticed  that  the  wool  is  first  yellow  in  color;  this  is  probably  due  to  the  formation  of 
chromium  chromate  in  the  fiber.  If  this  compound  is  exposed  to  the  action  of  strong 
light  it  will  suffer  a  rapid  reduction  to  chromium  oxide,  which  is  green  in  color;  hence  it 
is  best  not  to  expose  the  mordanted  wool  unevenly  to  light  for  any  length  of  time  before 
dyeing. 

Exp.  134.  Effect  of  Iron  Salts  in  the  Bath. — Alizarine  colors  are  much  affected  by 
the  presence  of  iron  salts  in  either  the  mordant  or  the  dyebath,  the  color  being  con- 
siderably dulled  through  the  formation  of  an  iron  color-lake  with  the  dyestuff.  To 
show  this  influence  in  the  mordant  bath,  mordant  a  skein  of  woolen  yarn  in  a  bath 
containing  3  per  cent  of  chrome,  4  per  cent  of  tartar,  and  a  few  drops  of  a  solution  of 
copperas.  After  mordanting  dye  as  usual  with  2  per  cent  of  Alizarine  Blue  NG;  wash 
and  dry  and  compare  the  color  thus  obtained  with  that  produced  with  the  same  mordant 
and  dyestuff  without  the  addition  of  the  iron  salt.  Mordant  a  second  skein  of  woolen 
yarn  in  the  usual  manner  with  3  per  cent  of  chrome  and  4  per  cent  of  tartar,  and  dye  as 


EXPERIMENTAL   STUDIES 


361 


before  with  2  per  cent  of  Alizarine  Blue  NG,  but  add  to  the  dyebath  a  few  drops  of  a 
solution  of  copperas.     Notice  the  effect  of  this  on  the  appearance  of  the  color. 

Exp.  135.  Comparison  of  Different  Mordants  on  Wool. — Mordant  a  skein  of  woolen 
yarn  in  a  bath  containing  3  per  cent  of  chrome  and  4  per  cent  of  tartar;  enter  at  140°  F., 
gradually  bring  to  the  boil,  and  continue  at  that  temperature  for  one-half  hour;  wash 
well  and  dye  in  a  fresh  bath  containing  2  per  cent  of  Alizarine  Red  SW;  enter  at  100°  F., 
gradually  bring  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour,  then  wash 
well  and  dry. 

Mordant  a  second  skein  of  woolen  yarn  in  a  similar  manner,  but  instead  of  chrome 
use  as  the  mordant:  10  per  cent  of  alum,  3  per  cent  of  tartar  and  2  per  cent  of  oxalic 
acid.  Wash  well,  and  dye  with  2  per  cent  of  Alizarine  Red  SW,  adding  to  the  dyebath  2 
per  cent  of  calcium  acetate,  1  per  cent  of  soap,  and  |  per  cent  of  tannic  acid,  each  of  these 
latter  ingredients  being  dissolved  separately  in  water.  This  mordant  is  principally 
used  for  red,  orange,  and  maroon  colors.  The  presence  of  copper  surfaces  in  the  dye- 
bath should  be  avoided  as  this  will  dull  the  colors.  The  harmful  influence  of  the  copper, 
however,  may  be  avoided  by  the  addition  of  3  ozs.  of  ammonium  sulphocyanide  per  100 
gallons  of  dye  liquor. 

Mordant  a  third  skein,  using  8  per  cent  of  copperas  as  the  mordant  with  8  per  cent  of 
oxalic  acid;  wash  well  and  dye  with  2  per  cent  of  Alizarine  Red  SW. 

Mordant  a  fourth  .skein  with  5  per  cent  of  bluestone  and  4  per  cent  of  tartar;  wash 
well  and  dye  with  2  per  cent  of  Alizarine  Red  SW. 

Mordant  a  fifth  skein  with  4  per  cent  of  stannous  chloride  and  2  per  cent  of  o.xalic 
acid;  wash  well  and  dj^e  with  2  per  cent  of  Alizarine  Red  SW. 

Compare  the  several  colors  obtained  on  the  different  mordants  with  the  same  dye- 
stuff,  and  also  preserve  samples  of  the  original  mordanted  yarn  before  dyeing  in  each 
case,  so  as  to  be  able  to  compare  the  colors  given  by  the  mordants  alone.  Make  a  record 
of  the  results  as  follows : 


Mordant. 

Color  of  mordanted  skein. 

Color  of  dyed  skein. 

Chromium 

Aluminium 

Iron 

Copper 

Tin 

Exp.  136.  After-mordanting  with  Chrome. — This  method  may  be  used  with  quite  a 
number  of  the  mordant  colors,  and  is  becoming  a  favorite  process,  as  only  one  bath  is 
required.  Dye  a  skein  of  woolen  yarn  in  a  bath  containing  2  per  cent  of  Anthracene 
Yellow  C,  2  per  cent  of  sulphuric  acid,  and  20  per  cent  of  glaubersalt;  enter  at  120°  F., 
gradually  bring  to  the  boil,  and  continue  at  that  temperature  for  one-half  hour;  then  lift 
the  skein  and  add  3  per  cent  of  chrome,  and  continue  the  boihng  for  fifteen  minutes; 
wash  and  dry.  Preserve  a  sample  of  the  color  before  chroming  and  compare  it  with  the 
chromed  color.  Many  of  the  mordant  dyes  are  now  prepared  in  such  a  manner  that 
they  have  slight  acid  properties  and  are  capable  of  being  absorbed  by  the  wool  fiber 
from  acid  baths;  these  dyes  are  chiefly  in  the  powder  form,  and  some  are  compounds  of 
the  alizarine  dyes  with  sodium  bisulphite;  they  are  also  much  more  soluble  in  water 
than  the  ordinarv  alizarines. 


362 


APPLICATION  OF  MORDANT  DYES 


Dye  a  skein  of  woolen  j-arn  in  a  bath  containing  4  per  cent  of  acetic  acid,  2  per  cent 
of  Acid  Alizarine  Green  R,  and  20  per  cent  of  glaubcrsalt.  Dye  in  the  same  manner  as 
before  and  then  add  3  per  cent  of  chrome  as  above;  wash  well  and  dry. 

Dye  a  third  skein  in  a  bath  containing  2  per  cent  of  sulphuric  acid,  4  per  cent  of  Dia- 
mond Black  F  and  20  per  cent  of  glaubcrsalt;  dye  as  before  and  after-chrome  with  2 
per  cent  of  chrome  and  1  per  cent  of  sulphuric  acid;  wash  well  and  dry. 


Fig.  187. — Padder,  Steamer  and  Washer  for  Mordanting  Cotton  and  Dyeing  Pieces. 

(Zittauer.) 


Dye  a  fourth  skein  with  2  per  cent  of  Diamond  Flavine  in  the  same  manner  and  after- 
chrome;  wash  and  dry.  In  each  case  preserve  a  sample  of  the  skem  before  chroming  in 
order  to  observe  anj'  change  in  the  color  due  to  the  chroming. 

Test  these  colors  as  to  their  fastness  to  washing  and  acids. 

Make  a  record  of  the  results  in  the  following  manner: 


Effect  of 
chroming. 

Washing  test. 

Dyestuff. 

Color. 

White 
wool. 

White 
cotton. 

Acid 
test. 

Anthracene  Yellow  C 

Acid  Alizarine  Green  R 

Diamond  Black  F 

Diamond  Flavine 

Exp.  137.  One-bath  Process. — The  one-bath  after-chroming  process  may  be  illus- 
trated as  follows: 

(a)  Dyeing  with  an  Acid-chrome  Color. — First  dye  in  a  bath  containing  3  per  cent 
of  Alizarine  Yellow  G  and  4  per  cent  of  acetic  acid;  after  dyeing  at  the  boil  for  one  hour, 
lift  the  goods  and  add  2  per  cent  of  chrome  and  1  per  cent  of  sulphuric  acid  previously 
dissolved  in  some  warm  water.     Re-enter  the  goods  and  boil  for  one-half  hour  longer. 


EXPERIMENTAL  STUDIES 


363 


This  is  an  example  of  an  azo  dyestuff  which  reacts  with  wool  as  an  ordinarj^  acid  dye, 
but  which  is  also  capable  of  forming  a  faster  color-lake  with  the  chrome  mordant. 

(6)  Dyeing  with  a  Chrome  Black  or  Chromotrop  Dye. — First  dye  in  a  bath  with  6 
per  cent  of  Chromotrop  2B,  20  per  cent  of  gUiuborsalt,  and  4  per  cent  of  sulphuric  acid; 
then  lift  the  goods  and  add  3  per  cent  of  chrome  and  boil  for  one-half  hour  longer.  This 
kind  of  a  dye  gives  an  acid  dyeing  which  is  of  a  purplish  red  color,  but  when  the  chrome 
mordant  is  applied  the  color  changes  to  a  full  black.  In  this  case  the  color-lake  with  the 
chrome  is  of  an  entirely  ditTerent  color  from  that  of  the  acid  dyestutY  itself. 

Exp.  138.  Various  One-bath  Methods. — The  one-bath  mordantmg  and  dyeing 
operation  may  Ije  understood  In-  a  consideration  of  the  following  e.xamples: 

(a)  Use  of  Meta-chrome  Dye. — Prepare  the  dyebath  by  first  adding  2  per  cent  of 
chrome  and  5  per  cent  of  anunonium  acetate,  and  then  add  2  per  cent  of  Meta-chrome 


Fig.  188. — Apparatus  for  Steaming  and  Fixing  Mordanted  Cotton. 


Brown;   enter  the  wool  at  1-10°  F.,  gradually  raise  to  the  boil  and  maintain  at  that  tem- 
perature for  three-quarters  of  an  hour. 

(6)  Use  of  Tin  Mordant  and  Cochineal  in  One  Bath. — Cochineal  was  formerly  very 
largely  used  for  the  production  of  scarlets  on  woolen  goods,  and  even  at  the  present  time 
it  still  is  used  for  this  purpose  to  a  considerable  degree.  For  the  production  of  this  color 
a  tin  mordant  is  employed  in  the  following  manner:  Prepare  the  dyebath  with  10  per 
cent  of  ground  Cochineal,  6  per  cent  of  o.xalic  acid  and  6  per  cent  of  stannous  chloride; 
boil  up  the  bath  for  about  ten  minutes,  then  add  sufficient  cold  water  to  bring  the  tem- 
perature down  to  about  150°  F.  The  wool  is  then  entered,  the  temperature  is  grad- 
ually brought  up  to  the  boil  and  the  dyeing  continued  for  one  hour.  Bj^  this  single- 
bath  process  a  scarlet  of  a  brighter  and  yellower  shade  is  obtained  than  with  the  two- 
bath  process  where  the  mordant  is  first  applied  and  the  dyeing  takes  place  in  a  fresh  bath. 


364 


APPLICATION  OF  MORDANT  DYES 


(c)  Dyeing  Logwood  in  One  Bath. — This  method  of  dyeing  is  sometimes  practiced 
for  the  production  of  dark  blue  or  black  on  cheap  shoddy  goods.  The  dyebath  is  pre- 
pared with  6  per  cent  of  Logwood  extract,  2  per  cent  of  oxalic  acid,  2  per  cent  of  tartar, 
4  per  cent  of  copperas  (ferrous  sulphate)  and  4  per  cent  of  bluestone  (copper  sulphate). 
Bring  the  bath  up  to  the  boil,  enter  the  goods  and  continue  dyeing  for  one  hour. 

Exp.  139.  Saddening  Method  of  Dyeing. — In  former  days  when  dyewoods  were  used 
to  a  much  greater  extent  than  they  are  now,  there  was  a  modification  of  the  ordinary 
process  of  mordanting  known  as  the  "  saddening  "  method.  In  this  process  the  goods 
were  first  mordanted  and  then  dyed  as  usual,  and  then  mordanted  again  with  another 
metalHo  .salt  chiefly  for  the  purpose  of  "  .saddening  "  or  dulling  the  shade,  and  also  for 
the  purpose  of  making  it  faster.     The  latter  eiTect  was 'probably  due  to  the  second 


Fig.  189. — Steaming  and  Ageing  Machine.     (Dchaitre.) 


mordant  fixing  some  of  the  excess  of  dyestuff  taken  up  by  the  fiber  and  which  was  not 
properly  combined  in  the  form  of  a  color-lake  with  the  metallic  salt  usetl  as  the  first 
mordant.  Sometimes  the  second  mordant  was  applietl  in  the  dyebath  after  the  dyeing 
was  completed,  though  more  generally  a  third  fresh  bath  was  used.  An  illustration 
of  this  method  of  dyeing  is  as  follows: 

(a)  Dyeing  a  Brown  with  Alizarine  or  Madder. — Mordant  in  the  usual  manner 
with  3  per  cent  of  chrome  and  4  per  cent  of  tartar,  and  then  dye  in  a  fresh  bath  with  20 
per  cent  of  ground  madder  root  and  2  per  cent  of  calcium  acetate.  Then  mordant  again 
in  a  third  fresh  bath  using  2  per  cent  of  copperas  and  4  per  cent  of  oxalic  acid.  In  many 
old  dyeing  recipes  there  will  often  be  found  a  direction  to  "  wash  in  the  river  "  after 
dyeing.  This  was  no  doubt  for  the  purpose  of  saddening  the  color  by  utilizing  the  iron 
and  lime  present  in  the  river  water  to  act  as  a  seeondury  mordant. 

(b)  Dyeing  an  Olive  Brown  with  Sandal  Wood.— Prepare  the  dyebath  with  50 
per  cent  of  Sandal-wood,  2  per  cent  of  Fustic  extract  and  1  per  cent  of  oxalic  acid;  boil 
the  wool  in  this  bath  for  one  and  one-half  hours,  then  add  2  per  cent  of  bluestone  and 


MORDANT  DYES  ON  SILK  AND  COTTON  365 

boil  for  fifteen  minutes  longer,  and  next  add  3  per  cent  of  copperas  and  continue  boil- 
ing for  another  fifteen  minutes.  A  slight  addition  of  soda  will  also  improve  the  appear- 
ance of  the  color  and  further  darken  the  shade. 

12.  Use  of  Mordant  Dyes  on  Silk. — The  mordant  colors  are  not  very 
extensively  used  for  the  dj^eing  of  silk  owing  to  the  fact  that  when  the 
silk  is  subjected  to  the  mordanting  operations,  especially  with  chrome,  it 
suffers  considerably  in  its  good  qualities,  and  particularly  in  its  luster. 
Furthermore,  dyeings  on  silk  are  usually  not  required  to  have  any  great 
fastness  to  washing  and  light,  but  it  is  sought  to  obtain  as  bright  and 
clear  a  color  as  possible  at  the  same  time  retaining  the  luster  and  softness 
of  the  fiber.  There  are  of  course  occasions  where  it  is  desirable  to  dye 
colors  on  silk  which  shall  have  pre-eminent  fastness  to  light  and  sometimes 
to  washing,  and  in  such  cases  it  may  be  necessary  to  employ  the  mordant 
dyes. 

As  chrome  cannot  be  used  with  advantage  on  silk  as  with  wool,  on 
account  of  its  tendency  to  destroy  the  luster  and  injure  the  fiber,  the 
mordanting  is  usually  done  with  chromium  chloride.  The  silk  is  steeped 
overnight  in  a  cold  bath  of  chromium  chloride  of  2°  Tw.,  or  chrome  alum 
of  9°  Tw.  may  be  used.  Squeeze  out  the  excess  of  liquor  and  wash  well, 
then  fix  for  half  an  hour  in  a  cold  bath  of  sodium  silicate  of  1°  Tw.,  and 
finally  rinse  very  thoroughly.*  A  basic  chromium  salt  is  thus  obtained  as 
a  mordant  on  the  fiber  without  particular  injury  to  the  latter.  Dye  in 
a  boiled-off  liquor  bath  broken  with  acetic  acid,  entering  the  goods  cold 
and  gradually  raising  to  the  boil  for  one  hour,  then  wash  and  brighten  in  a 
weak  bath  of  acetic  acid. 

13.  Mordant  Dyes  on  Cotton. — As  already  pointed  out,  cotton  has  very 
little  afhnitj^  for  metallic  bases.  Unlike  wool,  for  instance,  when  boiled 
in  a  solution  of  chrome  or  alum  and  tartar,  there  is  very  little  of  the  metallic 
hydrate  taken  up  by  and  fixed  in  the  fiber.  Owing  to  this  fact  the  general 
class  of  mordant  dyes  has  but  little  application  to  cotton.  Practically 
the  only  mordant  dj^e  used  in  cotton  dyeing  is  Alizarine  Red,  which  gives 
the  well-known  Turkey  Red.  In  cotton  printing,  however,  where  the 
application  of  metallic  mordants  is  more  readily  made,  a  number  of  the 
mordant  dyes  are  used.f 

*  In  the  dyeing  of  silk  noils,  where  the  preservation  of  the  luster  is  not  particularly 
important  the  mordant  dyes  may  be  used  in  the  same  manner  as  with  wool,  employ- 
ing either  the  top-chrome  or  the  meta-chrome  methods. 

t  In  America  there  is  practically  no  dyeing  of  Turkey  Red  on  cotton  yarns,  but  a 
large  quantity  of  gray  yarn  is  sent  to  England  where  it  is  dyed  Turkey  Red  and  returned 
here  for  weaving  purposes.  The  explanation  of  this  condition  probably  lies  in  the  fact 
that  such  dj'eing  is  a  highly  specialized  branch  and  is  practiced  even  in  England  and 
other  countries  in  only  very  limited  localities;  also  the  process  is  cumbersome  and 
requires  much  hand  labor  and  therefore  is  not  well  adapted  to  American  conditions. 
Alizarine  dyes,  however,  are  used  very  largely  in  calico-printing.     Turkey  Red  has 


366  APPLICATION  OF  MORDANT  D'i^S 

Owing  to  the  difficulty  of  properly  mordanting  cotton  directly  with 
metallic  salts,  rather  roundabout  and  complicated  methods  have  to  be 
adopted.  About  the  sole  mordant  emploj'cd  is  alumina,  and  in  order 
to  have  this  fixed  in  the  fiber,  it  is  necessarj"  to  treat  the  cotton  first  with 
tannin  (which  it  readily  absorbs  from  solution)  or  a  fattj-  acid  in  some 
suitable  form  such  as  Turkey-red  oil  (which  may  be  readily  padded  into 
the  fiber).  The  cotton  thus  prepared  when  treated  with  basic  aluminium 
salts  will  have  aluminium  tannate,  or,  which  is  far  preferable,  the  aluminium 
salt  of  the  fatty  acid  precipitated  within  the  fiber.  Padding  with  the  oil 
preparation  allows  of  considerable  metallic  base  being  fixed,  and  this 
permits,  therefore,  of  a  full  heavy  shade  of  red  being  dyed  with  alizarine.* 

In  the  mordanting  of  cotton  an  operation  kno\\Ti  as  "ageing"  is  intro- 
duced which  is  not  used  in  mordanting  wool.  Usually  both  the  oil  and  the 
alum  treatment  requires  an  ageing.  The  mordant  material  is  first  absorbed 
by  the  cotton  chiefly  by  mere  capillarity,  and  the  object  of  the  ageing  is  to 
bring  about  a  thorough  and  even  decomposition  of  the  mordant  compound 
within  the  fiber  so  that  the  insoluble  mordant  is  fixed.  The  ageing  is  usu- 
ally carried  out  by  hanging  the  material  in  suitable  warm  moist  rooms  for 
several  days.  In  former  days  a  dunging  operation  was  often  used,  whereby 
the  goods  were  soaked  in  a  decoction  of  cow's  dung  for  the  purpose  of 
decomposing  the  metallic  salt  and  fixing  the  insoluble  mordant  base. 

Turkey  Red  is  the  name  applied  to  the  color  obtained  on  cotton  by 
using  madder  or  alizarine  on  a  mordant  of  aluminium  and  oil.  This  color 
was  formerly  of  very  great  importance,  and  is  still  very  largely'  used,  though 
in  many  instances  it  is  replaced  by  reds  obtained  with  Primuline  or  with 
Paranitraniline.  Though  madder  was  used  in  former  years  for  this  class 
of  dyeing,  at  present  the  artificial  alizarine  is  altogether  employed. 

Turkey-red  dyeing  is  a  rather  complicated  process,  although  the 
various  operations  may  vary  considerably  with  the  exact  character  of  the 
color  desired. 

14.  Experimental.  Exp.  140.  Old  Process  for  Turkey  Red. — Take  a  skein  of  well- 
bleached  yarn  which  has  first  been  boiled  out  in  caustic  soda  and  mordant  in  a  bath  con- 
taining acetate  of  aluminium  at  9°  Tw.     It  is  worked  in  this  bath  until  the  yam  is  thor- 

largely  been  replaced  on  both  yarn  and  piece-goods  by  Para  Red  (paranitraniline  diazo- 
tized  and  coupled  with  beta-naphthol),  though  this  latter  color  is  far  inferior  to  Turkey- 
Red  in  fastness.     It  is,  however,  much  cheaper  and  easier  to  apply. 

*  In  olden  times  the  process  of  Turkey-red  dyeing  required  as  much  as  four  months' 
time  for  completion ;  newer  processes,  however,  have  cut  this  time  down  to  about  three 
days,  though  with  some  sacrifice  to  fastness.  The  Turkey-red  dye  is  not  a  simple  lake 
of  aluminium  and  alizarine,  but  a  rather  complex  lake  containing  aluminium,  calcium, 
and  alizarine,  together,  no  doubt,  with  a  fattj'  acid.  In  the  old  methods  of  dj-eing 
Turkey  Red  a  rancid  olive  oil  was  used,  whereas  at  present  the  oil  employed  is  a  sul- 
phated  castor  oil  (commonly  known  as  Turkey-red  oil). 


EXPERIMENTAL  STUDIES 


367 


oughly  and  evenly  impregnated 
with  the  mordant;  then  wring  out, 
and  dry  at  a  temperature  of  120°  F. 
for  twenty-four  hours. 

Next  work  in  a  solution  contain- 
ing 10  parts  of  Turkey-red  oil  to  90 
parts  water.  The  cotton  must  be 
thoroughly  and  evenly  impregnated 
with  this  solution.  Wring  out  and 
dry  at  a  temperature  of  1G0°  F.  for 
twelve  hours. 

Next  mordant  again  in  the  bath 
of  aluminium  acetate  as  described 
above;  squeeze  and  dry  as  before. 

Next  work  in  a  bath  containing 
0.5  part  chalk  to  100  parts  water,  at 
100°  F.  for  one-half  hour.  Then 
wash  well  with  clean  water. 

Next  d}'c  in  a  bath  containing 
15  per  cent  Alizarine  paste  and  4 
per  cent  calcium  acetate;  enter  at 
70°  F.,  and  gradually  raise  to  the 
boil. 

Next  oil  the  cotton  again  as  de- 
scribed above. 

Next  steam  for  one  hour  at  one 
atmosphere  pressure,  and  wash  well. 

Finally  boil  for  one  hour  in  a 
bath  containing  5  parts  soap  to  1000 
parts  water. 

The  old  or  emulsion  process  for 
dyeing  Turkey  Red  on  cotton  is 
summarized  as  follows  by  Whit  taker 
in  an  adaptation  from  Felsen's 
"  TurJcisch  Rot  und  Seine  Concur- 
renten: " 

First  Operation — Boiling. — The 
yarns  are  never  bleached  by  chem- 
icing  (or  treatment  with  chloride 
of  lime  solution),  but  simply  freed 
from  the  naturally  adhering  fatty 
and  resinous  substances  by  "  bowk- 
ing  " — i.e.,  boiling  under  pressure 
with  alkaUne  liquors.  The  general 
method  is  to  boil  the  yarn  for  four 
to  five  hours,  under  a  pressure  of  30 
lbs.,  in  a  solution  of  caustic  soda 
lye  of  1°  Tw.  Some  use  silicate  or 
carbonate  of  soda  or  work  in  low- 
pressure  kiers;  in  these  cases  the 
boiling  has  to  be  continued  for  six 
to  eight  hours.     When  the  yarn  has 


368  APPLICATION  OF  MORDANT  DYES 

been  thoroughly  cleaned  in  this  way  it  is  washed  well  with  water,  hydro-extracted,  and 
dried  in  a  stove  at  120  to  140°  F.  (50  to  60"  C). 

Second  Operation — First  Green  Liquor. — The  yarn  is  passed  into  the  so-called  first 
green  liquor,  which  is  prepared  b}^  mixing  rancid  olive  oil  with  sodium  carbonate  and 
sheep  or  cow  dung.  The  most  suitable  olive  oil  is  that  which  forms  the  most  perfect 
and  permanent  emulsion  with  the  smallest  quantity  of  sodium  carbonate.  For  100  lbs. 
of  yarn  the  bath  is  made  up  with  15  lbs.  of  emulsive  oil,  I2  to  2  lbs.  of  dung,  20  gallons  of 
water,  and  so  much  of  a  concentrated  solution  of  sodium  carbonate  as  will  bring  the  liquor 
to  a  specific  gravity  of  2°  Tw.  In  this  bath  the  yarn  is  thoroughh'  saturated  with  the 
emulsive  Hquor,  at  a  temperature  of  about  100°  F.  (40°  C),  for  half  a  minute,  and  then 
wrung  out  evenly.  This  process,  usually  called  tramping,  is  done  by  "  tramping 
machines,"  which  steep  the  single  hanks  into  the  liquors  and  often  also  wring  out  the 
hanks  without  much  hand  labor.  After  being  well  prepared  the  hanks  are  thrown  out 
into  heaps  for  the  night ;  on  the  following  morning  thej'  are  ex-posed  to  the  open  air  until 
thej-  feel  dry;  and  finally,  they  are  placed  in  ''  stoves  "  heated  to  140°  F.  (60°  C.)  for 
twelve  hours  (sto\-ing).  In  some  works  which  produce  the  verj'  best  kinds  of  Turkey 
Red,  as  regards  fastness  to  alkalies  and  to  chlorine,  the  yams  are  exposed  in  the  open 
air  for  three  or  more  days,  and  then  they  need  not  be  placed  in  the  stoves;  while  at 
present  they  are  frequently  brought  straight  into  the  stoves  after  having  been  pUed  up 
overnight.  In  this  last  case  the  steam  given  off  in  large  quantities  during  the  drj'ing 
must  be  allowed  to  escape,  as  its  retention  causes  the  fibers  to  be  tendered.  During 
the  prolonged  ex-posure  of  the  j-arns  in  the  open  air,  the  fiber  is  bleached  by  the  sun, 
especially  in  the  sunny  Eastern  countries;  the  slightly  greater  brilliancy  of  the  Turkey 
Reds  which  have  been  produced  in  the  East  is  attributable  to  this  action. 

Third  and  Fourth  Operations — Second  and  Third  Green  Liquors. — These  consist  of  a 
second  and  third  repetition  of  the  second  operation,  the  object  being  to  increase  the 
amount  of  oil  in  the  fiber.  The  baths  are  prepared  exactly  as  for  the  first  green  hquor, 
and  the  goods  are  steeped,  ex-posed  to  the  air,  and  stoved  as  before;  but  it  is  not  neces- 
sarj'  to  pile  them  up  to  lie  in  heaps  overnight. 

Some  of  the  alkali  which  is  used  in  preparing  the  bath  is  liberated  by  the  chemical 
transformation  of  the  oil  in  the  fiber  and  dissolves,  during  the  second  and  third  treat- 
ment, in  the  green  liquor,  which  is  absorbed  bj-  the  yarn.  The  excess  of  this  liquor,  which 
is  pressed  out  by  the  wringing  of  the  hanks,  if  allowed  to  flow  back  into  the  tramping 
tank,  would  change  the  specific  gravity  of  the  bath,  and  as  it  is  of  importance  that  all  the 
liquors  should  be  maintained  regularly  of  the  same  specific  gravity,  only  the  liquor  which 
is  expressed  during  the  steeping  in  the  first  oil  bath  is  allowed  to  run  back  into  the  tramp- 
ing tank;  that  from  the  second  and  third  oil  baths  is  collected  separately  and  used  only 
after  being  reduced  to  its  original  specific  gravity'  by  dilution  with  water. 

About  30  per  cent  of  oil  of  the  weight  of  the  yarn  is  used,  but  onlj'  a  part  of  this  is 
permanently  fLxed  in  the  fiber. 

Fijth,  Sixth,  Seventh  and  Eighth  Operations — First,  Second,  Third,  and  Fourth  White 
Liquor  Baths. — The  yarn  has  been  impregnated  with  oil,  and  the  latter  transformed  into 
such  a  state  by  the  hanging  and  stoving  operations  that  it  is  not  readily  stripped  by 
weak  alkaUne  liquors.  A  part  of  the  absorbed  oil,  however,  has  not  become  insoluble 
or  adheres  superficialh'  to  the  fiber.  This  oU  is  removed  by  repeated  treatments  with 
alkah  in  order  to  avoid  the  formation  of  the  "  surface  "  color,  which  is  always  dis- 
posed to  rub  and  smear  off. 

The  goods  are  tramped  for  this  purpose  four  times  in  solution  of  sodium  carbonate 
(2°  Tw.),  wrung  out,  hung  up  in  the  open  air,  and  "  stoved  "  as  in  the  previous  opera- 
tions; a  different  bath  is  used  each  time.  The  oil  which  is  stripped  from  the  fiber  forms 
an  emulsion  and  imparts  a  white  color  to  the  bath,  hence  the  name  white  baths.  The 
old  white  baths  may  be  used  for  the  preparation  of  fresh  green  liquors. 


EXPERIMENTAL  STUDIES  369 

Ninth  Operation — Steeping. — The  yarn  is  steeped  for  a  further  purification  in  water 
at  130°  F.  (55°  C),  for  twenty-four  hours,  washed  well  and  stoved  at  140°  F.  (G0°  C). 
If  it  still  contains  much  unmodified  oil,  a  solution  of  sodium  carbonate  at  ^°  Tw.  is  used, 
the  yarn  is  steeped  two  hours  in  tepid  water,  washed  and  dried. 

Tenth  Operation — Sumacing  or  Galling. — An  infusion  is  prepared  of  12  lbs.  of  best 
leaf  sumac  for  every  100  lbs.  of  yarn,  and  the  cold  solution  is  filtered  and  diluted  to  1-2° 
Tw.  The  yarn,  while  still  warm  from  the  stoving  operation,  is  steeped  for  six  hours  in 
the  solution  at  120°  F.  (50°  C),  and  then  hydro-extracted.  It  thus  takes  up  a  certain 
amount  of  tannic  acid. 

Eleventh  Operation — Aluming  or  Mordanting. — Cake  alum  is  dissolved  in  warm  water, 
and,  when  nearly  cold,  a  cold  solution  of  one-fourth  its  weight  of  soda  crystals  is  added. 
Fifteen  to  20  per  cent  of  red  liquor,  16°  Tw.,  and  0.5  to  0.7  per  cent  tin  crystals  (of  the 
weight  of  the  alum)  are  often  added  to  the  liquor,  but  these  additions  are  not  essential. 
The  addition  of  stannous  chloride  is  made  to  prevent  ferric  oxide  from  entering  into  the 
color-lake  and  to  introduce  tin  in  some  form  into  the  color,  to  make  the  shade  more 
fiery.  In  this  solution,  which  is  brought  to  a  specific  gravity  of  8°  Tw.  and  kept  at  a 
temperature  of  100  to  120°  F.  (40  to  50°  C),  the  yarn  is  steeped  for  twenty-four  hours, 
then  thoroughly  washed  and  hydro-extracted.  By  this  operation  aluminium  salts 
are  formed,  with  the  previously  fixed  o.xyfatty  acids  and  tannic  acids. 

The  yarn,  which  is  at  last  ready  for  dyeing,  should  now  possess  a  deep  yellowish 
tinge. 

Twelfth  Operation — Dyeiyig. — The  goods  are  best  dyed  in  wooden  vats  with  closed 
steam  coils  of  tinned  copper.  Iron  vessels  must  be  covered  from  time  to  time  with  a 
coating  of  insoluble  iron  tannate,  by  boiling  out  with  a  weak  decoction  of  sumac;  if 
this  is  not  done  the  red  shade  will  be  rendered  dull  by  iron  compounds. 

The  water  used  for  dyeing  should  indicate  2  to  3°  of  hardness  (Clark's  scale);  if  it 
contains  little  or  no  lime,  a  suitable  amount  of  ground  chalk  (about  ^  per  cent  of  the 
weight  of  the  20  per  cent  Alizarme  paste  employed)  must  be  added.  Very  hard  water, 
or  water  which  contains  iron,  cannot  be  used  in  Turkey-red  dyeing. 

The  dyebath  is  prepared  with  8  to  10  per  cent  of  Alizarine  (20  per  cent),  1  per  cent  of 
tannic  acid  (or  3  to  5  per  cent  of  good  sumac),  and  about  30  per  cent  of  ox-blood  (of  the 
weight  of  the  cotton).  The  yarn  is  entered  into  the  cold  dyebath,  the  temperature  grad- 
ually raised  to  boiling  during  one  hour;  and  maintained  so  for  thirty  to  sixty  mmutes 
longer.     After  dyeing,  rinsing  in  water  is  advisable. 

The  goods  now  possess  a  dull  red  color,  which  is  transformed  by  the  "  clearing  " 
processes  into  the  brilliant  Turkey-red  shade. 

Thirteenth  Operation — First  Clearing. — The  yarn  is  boiled  for  four  hours  in  open 
pans  or  under  a  pressure  of  3  to  4  lbs.  with  about  3  per  cent  of  palm-oil  soap,  dissolved 
in  a  sufficient  quantity  of  water. 

Fourteenth  Operation — Second  Clearing. — The  yarn  is  boiled  for  one  to  two  hours  at 
3  to  4  lbs.  pressure  with  a  solution  of  2^  per  cent,  of  palm-oil  soap  and  0.15  per  cent  of 
tin  crystals  (on  the  weight  of  the  cotton),  and  afterwards  thoroughly  washed  in  water. 
The  excess  of  water  is  removed  bj'  mechanical  means  (hydraulic  press  or  hydro-extractor) 
and  then  the  goods  are  dried  in  an  open-air  shed.  This  closes  the  long  chain  of  opera- 
tions. 

Exp.  141.  Short  Process  for  Turkey  Red. — Use  a  skein  of  well-bleached  and  boiled- 
out  cotton. 

(1)  Sumac  in  a  bath  containing  5  parts  sumac  in  100  parts  water;  immerse  for  twelve 
hours;    squeeze. 

(2)  Mordant  in  aluminium  acetate  at  9°  Tw.,  working  until  the  cotton  is  thoroughly 
and  evenly  impregnated,  squeeze,  and  dry  for  twenty-four  hours  at  120°  F. 


370 


APPLICATION  OF  MORDANT  DYES 


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EXPERIMENTAL  STUDIES 


371 


(3)  Chalk  in  a  bath  containing  0.5  part  chalk  in  100  parts  water  at  100°  F.  for  one- 
half  hour;  wash  well. 

(4)  Dye  with  15  per  cent  Alizarine  paste  and  4  per  cent  calcium  acetate;  entering 
at  70°  F.  and  gradually  bring  to  the  boil;  continue  at  this  temperature  for  one  hour. 

(5)  Brighten  by  boiling  for  one  hour  in  a  bath  of  5  parts  soap  to  1000  parts  water. 
This  process  is  cheaper  than  the  foregoing,  but  does  not  give  as  bright  shades. 

The  new  process  for  dyeing  Turkey  Red  may  be  summarized  as  follows  (adaptation 
by  Whittaker  from  Felsen's  "  Turkish  Rot  und  Seine  Concurrenten  "): 

Sulphated  Oil  or  Turkey-red  Oil  Process  for  Yarn  and  Piece-goods. — This  process 
also  yields  beautiful  red  shades,  which  are,  however,  not  quite  as  fast  as  those  obtained 
by  the  preceding  process. 

Turkey-red  oil  prepared  from  castor  oil  is  most  generally  used;  sulphated  oil  can  be 
employed,  but  has  not  proved  so  good,  as  it  does  not  oxidize  and  polymerize  as  readily. 


Fig.  192. — Tentering  and  Drying  Machine.     ^Heathcote.) 


Very  good  results  are  obtained  with  a  carefully  made  castor-oil  soap — i.e.,  sodium 
ricinoleate,  but  this  is  not  used  on  the  large  scale. 

First  Operation — Boiling. — This  is  done  exactly  in  the  same  way  as  in  the  preceding 
processes.  Bleaching  has  to  be  resorted  to  in  the  case  of  light  shades  (especially  pinks) 
to  obtain  bright  tints,  but  the  action  of  the  chlorine  has  to  be  restricted  as  far  as  pos- 
sible to  the  destruction  of  the  natural  coloring  matters  of  the  cotton  fiber,  while  the 
formation  of  oxycellulose  must  be  prevented;  for  this  reason,  hypochlorite  of  soda  is 
preferable  to  bleaching  powder  or  better  stiU  is  bleaching  with  potassium  permanganate. 

Second  Operation — Oil  preparing. — The  washed  goods  are  hydro-extracted,  but  not 
dried,  and  then  worked  in  a  bath  containing  10  to  20  lbs.  of  neutralized  Turkey-red  oil 
(50  per  cent)  for  every  10  gallons  of  water.  When  thoroughly  saturated  with  the  Uquor 
they  are  evenly  wrung  out. 

Third  Operation — Staving. — The  oiled  goods  are  dried  at  temperatures  ranging  from 
100  to  140°  F.  (40  to  60°  C).  For  the  production  of  a  bright  and  intense  red,  the 
operations  of  oiling  and  drying  and  subsequent  aluming  are  repeated  once  or  twice. 


372  APPLICATION  OF  MORDANT  DYES 

Frequcnth'  the  oiled  goods  are  steamed  under  a  pressure  of  8  lbs.  for  sixty  to  ninety 
minutes,  but  this  is  not  essential. 

The  compounds  constituting  the  Turkey-red  oil  are  decomposed  by  the  operations  of 
oiling,  drj'ing,  and  steaming,  ammonium  or  sodium  sulphate  and  various  organic  acids 
being  formed.  The  latter  are  similar  to  the  corresponding  substances  deposited  in  the 
fiber  in  the  older  processes,  and  consist  of  products  of  the  oxidation  and  polymerization 
of  ricinoleic  acid,  etc. 

Fourth  Operation — Aluming. — The  goods  are  worked  for  five  or  six  hours  in  a  warm 
bath  100°  F.  (40°  C.)  of  red  liquor  10°  Tw.  or  of  basic  aluminium  sulphate  10°  Tw.,  well 
wrung  out  and  dried  at  100  to  120°  F.  (40  to  50°  C.) 

Fifth  Operation — Chalking. — This  resembles  the  treatments  in  the  other  Turkey-red 
processes,  by  which  the  material  is  worked  in  a  weak  alkaline  bath  for  the  purpose  of 
purifying  it  from  an  excess  of  oil;  in  this  process,  however,  the  purification  takes  place 
after  the  aluming,  so  that  not  only  is  there  a  removal  of  oil,  but  also  a  more  complete 
precipitation  of  the  alumina  which  has  been  absorbed  by  the  fiber  during  the  aluming. 
A  chalk  bath  is  generally  employed  for  this  purpose  (chalking).  Brighter  colors  are 
said  to  be  produced  when  phosphate  of  soda  or  ammonium  carbonate  are  emploj'ed  as 
fixing  agents.  Arsenate  of  soda  gives  still  brighter  colors  than  the  phosphate.  The 
cotton  is  worked  for  thirty  minutes  at  90  to  100°  F.  (30  to  40°  C.)  in  a  bath  containing 
5  lb.  of  ground  chalk  per  10  gallons  of  water,  then  thoroughly  washed  and  dyed  without 
drying. 

Sixth  Operation — Dyeing. — Moderately  hard  water,  free  from  iron,  exactly  as  in  the 
emulsion  process,  is  required.  For  very  deep  shades  about  15  per  cent  of  Alizarine 
(yellow  shade)  is  necessary ;  a  fine  pink  is  obtained  by  this  process  with  1  or  2  per  cent  of 
Alizarine  V.  The  whole  quantity  of  the  dyestuff  is  added  to  the  dyebath,  and  the  goods 
are  introduced  at  a  temperature  not  exceeding  25°  C.  and  turned  for  twenty  minutes; 
in  about  half  an  hour  the  bath  is  heated  to  140  to  160°  F.  (60  to  70°  C),  and  main- 
tained at  this  temperature  for  one  hour.  After  dyeing,  the  goods  are  wrung  out  and 
dried  with  or  without  previous  washing. 

Seventh  Operation — Second  Oil  Preparing. — The  material  is  impregnated  once  more 
with  a  solution  of  neutralized  Turkey-red  oil  (5  to  10  lbs.  per  10  gallons)  and  dried. 
The  second  oiling  may  be  dispensed  with  or  take  place  after  the  mordanting.  In  the 
latter  case  a  fresh  treatment  in  a  weak  solution  of  basic  aluminium  sulphate  or  red  liquor 
follows  for  the  purpose  of  fixing  the  oil. 

Eighth  Operation— Steaming.— The  goods  are  steamed  for  one  hour  at  15  lbs.  pressure 
or  two  hours  without  pressure  to  develop  the  color.  According  to  a  more  recent  process, 
neither  oiling  nor  steaming  follows  the  dyeing;  the  dj^ed  goods  are  simply  heated  for 
some  hours  in  water  under  considerable  pressure.  It  is  said  that  the  beauty  increases 
up  to  a  pressure  of  about  65  lbs.  When  the  goods  come  from  the  dyebath,  they  possess 
an  orange  tinge,  and  a  part  of  the  dyestuff  can  be  stripped  by  rinsing  in  water,  since  it  is 
not  intimately  combined  with  the  mordants.  The  complex  lake  is  formed  by  steaming 
only,  and  the  material  then  receives  a  dull  red  color  which  is  brightened  by  the  clearing 
baths. 

Ninth  and  Tenth  Operations — First  and  Second  Clearings. — These  operations  may  be 
executed  as  in  the  older  processes;  but  less  severe  treatments  are  sufficient.  A  fine 
brilliant  red  is  produced  by  once  or  twice  boiling  under  4  to  8  lbs.  pressure  for  thirty  to 
sixty  minutes  in  ]  per  cent  soap  solutions  (without  any  further  additions).  The  soaped 
goods  are  well  washed  in  water  and  dried  at  a  moderate  temperature. 

The  process  can  be  simplified  by  raising  the  temperature  of  the  dj'ebath  to  the  boiling 
point.  In  this  case  the  oiling  after  dyeing  is  to  be  omitted,  and  the  steaming  may  be 
dispensed  with.  But  the  shade  is  never  so  bright  or  fast  as  that  of  the  colors  which  have 
been  produced  ut  a  lower  temperature  with  subsequent  steaming. 


PRINCIPAL   MORDANT  DYES 


373 


16.   List   of   the   Principal    Mordant    Dyes 
(a)  Applicable  to  Previously  Mordanted  Wool 


Acid  Anthracene  Browns 
Acid  Chrome  Black 
Acid  Chrome  Brown 
Ahzarine 
Alizarine  Blacks 
Alizarine  Blue  (all  brands) 
Alizarine  Blue  Black  Wand 

SW 
Alizarine  Bhie  S  (all  brands) 
Alizarine  Bordeaux 
Alizarine  Brown  (all  brands) 
Alizarine  Chrome  Black  W 
Alizarine      Cyanine      (all 

brands) 
Alizarine  Cyanine  Black 
Alizarine  Dark  Blues 
Alizarine  Fast  Blacks 
Alizarine  Gray  G  and  R 
Alizarine  Greens 
Alizarine   Indigo   SW    and 

SMW 
Alizarine  Maroon 
Alizarine  Orange 
Alizarine  Purpurine 
Alizarine  Reds  (pastes  and 

powders) 
Alizarine  Sapphire 
Alizarine  Viridine  FF  and 

DG 
Alizarine  Yellows 
Alizarme  Yellow  N  powder 
Anthracene  Blue 
Anthracene      Brown     (all 

brands) 


Anthracene  Dark  Blue  W 
Anthracene  Red 
Anthracene  Yellow 
Anthracjd  Fast  Red 
Anthracyl  Blue  G  and  R 
Anthraquinone  Blue 
Anthraquinone  Green 
Anthraquinone  Violet 
Azo  Chromine  G 
Blue  PRC 

Brilliant  Ahzarine  Blues 
Brilliant  Alizarine  Cyanine 
Carbazol  Yellow 
Cclestine  Blue  B 
Chromazurine  S 
Chrome  Blue 
Chrome  Brown 
Chrome  Fast  Yellow 
Chrome  Patent  Green 
Chrome  Violet 
Chrome  Yellows 
Chromocyanine  B  and  V 
Cloth  Brown 
Cloth  Orange 
Cloth  Red  B,  G 
Cloth  Scarlet 
Coeruleine 

Coeruleine  S  in  paste 
Coreine  2P,  AB,  and  AR 
Cyananthrol 
Delphine  Blue 
Diamond  Blacks 
Diamond  Brown  paste 
Diamond  FlavLne  G 


Diamond  Orange 

Diamond  Yellow 

Dioxine 

Domingo  Chrome  Red 

Domingo  Chrome  Yellow 

Fast  Brown 

Fast  Mordant  Yellow 

Fast  Printing  Yellow  3G 

Gallamine  Blue 

Gallanil  Indigo  PS 

Gallanil  Violet 

Gallocyanine 

Galleine 

Galloflavine 

Gallozinc  A 

Gambine  G  and  R 

Indochromine 

Meta-chrome  Brown 

Milling  Brown 

Milling  Orange 

Milling  Red 

Milling  Yellow 

Mordant  Yellows 

Phenocyanine  B  and  VS 

Prune 

Resoflavine 

Rufigallol 

Sulphamine 

Sulphamine  Brown  A  and  E 

Salicine  Red 

Salicine  Yellows 

Wool  Red 

Wool  Yellow 


(b)   Suitable  for  After-mordanting 


Acid  Alizarine  Black 
Acid  Alizarine  Blue  BB,  GR 
Acid  Alizarine  Brown  B 
Acid  Alizarine  Gray 
Acid  Alizarine  Green 
Acid  Alizarine  Grenat 
Acid  Alizarine  Yellow 
Acid  Anthracene  Brown  R, 

T,  and  W 
Acid  Chrome  Black  B  and 

C 


Arid  Chrome  Brown 
Alizarine  Black,  powder 
Alizarine  Blues,  powder 
Alizarine  Blue  SAP,   SAE, 

SKY 
Alizarine  Cyanine  Green 
Alizarine  Greens 
Alizarine  Sapphire 
Alizarol  Black 
Alizarol  Brown 
Alizarol  Orange 


Alizarol  Yellow 
Alphanol  Blue 
Anthracene  Acid  Blacks 
Anthracene  Acid  Blue 
Anthracene  Acid  Brown  (all 

brands) 
Anthracene  Blue  Black 
Anthracene  Chromate  Brown 
Anthracene  Chromate  Green 
Anthracene  Chrome  Black 
Anthracene  Chrome  Blue 


374 


APPLICATION  OF  MORDANT  DYES 


Anthracene  Chrome  Browns 
Anthracene  Red 
Anthracene  Yellows 
Buffalo  Chrome  Black 
Chromate  Blacks 
Chrome  Black  B  and  T 
Chrome  Blue 
Chrome  Fast  Blacks 
Chrome  Fast  Reds 
Chrome  Fast  Yellows 
Chrome  Green 
Chrome  Patent  Black 
Chrome  Yellows 
Cloth  Red  B,  G 
Cypress  Blue 


Cypress  Green  Mono-chrome  Brown 

Diadem  Chrome  Black  Mono-chrome  Gray 

Diadem  Chrome  Blue  Black  Mono-chrome  Orange 
Diadem  Chrome  Green  Mono-chrome  Yellow 

Diadem  Chrome  Red  Palatine  Chrome  Black  (Pal 

Diamond  Black  (all  brands)     atine  Chrome  Black  and 


Diamond  Browns 
Diamond  Flavine  G 
Diamond  Green  B 
Domingo  Chrome  Black 
Domingo  Violet  Black 
Emin  Red 

Meta-chrome  Bordeaux 
Meta-chrome  Orange 
Meta-chrome  Yellows 


Palatine  Chrome  Blue  re- 
quire the  addition  of  a 
small  quantity  (1  per 
cent)  of  sulphuric  acid  to 
the   dj'ebath) 

Palatine  Chrome  Blue 

Palatine  Chrome  Brown  W 

Serichrome  Blue 

Serichrome  Green 


(c)  Suitable  for  Dyeing  in  an  Acid  Bath  without  After-chroming 


Alizarine  Cyanine  Green 
Alizarine  Heliotrope 
Alizarine  Irisol 


Alizarine  Pure  Blue 
Alizarine  Sapphire 
Diamond  Brown  3R 


Fast  Green  G 
Milling  Green  S 
Naphthol  Green  B 


Acid  Alizarine  Black  R 
Azo  Fuchsine  B  and  G 
Azo  Rubine 


(d)  Chrome  Developed  Dyestuffs 

Carmoisine  B  Chromotrop  (all  brands) 

Chrome  Brown  BO  and  RO  Florida  Red 
Chromogen  I 


(e)  Dyes  for  Shading.  Not  Affected  by  Chrome 


Acid  Chrome  Black  B,  G 
Acid  Violet  4B 
Acid  Yellow  AT 
Alkali  Fast  Green  6B 
Anthracene  Red 
Anthracite  Black 
Azo  Crimson  3 
Azo  Fuchsine  6B 


Bordeaux  extra 
Brilliant  Milling  Blue 
Brilliant  Milling  Green 
Diamine  Fast  Red  F 
Fast  Acid  Violet  lOB 
Fast  Greens 
Fast  Light  Yellows 
Formj'l  Blue 


Formyl  'N'iolets 
Indocyanines 
Rhodamine  B,  G 
Soluble  Blues 
Sulphon  Cyanines 
Tartrazine 
Wool  Red  B 


CHAPTER  XVII 

SULPHUR  DYES 

1.  Nature  of  the  Sulphur  Dyes. — These  colors  belong  to  the  general 
group  of  substantive  cotton  dyes  and  are  of  rather  recent  introduction. 
They  are  so  called  because  they  consist  of  sulphur  compounds,*  and  are 
dyed,  as  a  rule,  with  the  addition  of  sodium  sulphide  to  the  bath.  The 
first  of  these  dyes  was  discovered  in  1867  by  two  French  chemists,  f  and 
was  known  as  Cachou  de  Laval ;  it  was  prepared  by  fusing  wood  shavings 
and  sawdust  with  sodium  sulphide  or  sulphur.  As  it  had  but  httle  tinc- 
torial power  it  was  not  a  success  as  a  dyestuff.J  During  recent  years,  how- 
ever, a  large  number  of  these  dyes  have  appeared  in  almost  all  colors  with 
the  exception  of  red,  and  even  a  so-called  sulphur  red  dye  has  been  brought 
out,  but  it  is  far  from  being  a  pure  red  color.  §  We  have  Sulphur  Blacks, 
Browns,  Blues,  Yellows,  and  Greens.     The  sulphur  colors  are  especially 

*  The  chemical  nature  of  the  sulphur  dyes  is  still  more  or  less  undetermined,  but  it  is 
probable  that  they  consist  of  a  mixture  of  complicated  organic  derivatives,  in  which 
sulphur  appears  to  be  a  constituent  part. 

t  Croissant  and  Bretonniere. 

J  The  discovery  of  the  sulphur  dyes  must  be  credited  to  the  French.  Some  years 
after  the  introduction  of  Cachou  de  Laval  another  French  chemist  named  Vidal  dis- 
covered that  black  sulphur  dyes  could  be  produced  by  fusing  various  aromatic  amines 
with  sodium  sulphide  and  sulphur.  This  soon  led  other  investigators  into  the  field, 
and  between  the  years  1890  and  1910  a  large  number  of  sulphur  dyes  had  been  prepared. 
In  the  United  States  the  sulphur  dyes  were  among  the  first  to  be  developed  after  the 
outbreak  of  the  Great  War,  and  at  the  present  time  practically  a  full  line  of  the  important 
sulphur  dyes  are  made  in  this  country,  and  the  methods  of  manufacture  have  been 
so  improved  that  these  dyes  are  now  available  in  a  purer  and  more  concentrated  form 
than  they  were  when  formerly  imported  from  Germany.  Though  Sulphur  Blacks  may 
be  made  from  quite  a  number  of  different  materials,  by  far  the  most  important  black 
is  the  one  made  from  dinitro-phenol,  which  in  turn  is  made  by  nitrating  chlorbenzol. 

§  Thio-indigo  Red  is  sometimes  referred  to  as  a  red  sulphur  dye,  but  this  is  incorrect, 
for  this  dye  cannot  be  considered  as  belonging  to  the  class  of  sulphur  dyes;  it  is  a  vat 
dye  and  belongs  to  the  same  group  as  Indigo.  In  its  method  of  manufacture  it  also 
differs  radically  from  the  true  sulphur  dyes.  On  the  other  hand,  Hydron  Blue,  though 
usually  classed  with  the  vat  dyes  and  dyed  after  the  manner  of  Indigo,  is  properly 
speaking  a  sulphur  dye,  being  made  according  to  the  general  methods  for  this  group, 
and  also  from  the  fact  that  it  may  be  used  as  a  sulphur  dye  in  a  bath  with  sodium 
sulphide. 

375 


376 


SULPHUR  DYES 


remarkable  for  their  fastness  to  washing  and  even  fulling,  as  well  as  to 
acids  in  cross-dyeing.     They  also  furnish  deep,  heavy  shades  on  cotton. 

2.  Dissolving  the  Sulphur  Dyes. — Some  of  the  sulphur  dyes  are  directly 
soluble  in  water,  but  these  as  a  rule  are  not  the  pure  dyestuffs,  but  contain 
sufficient  residual  sodium  sulphide  left  from  the  process  of  manufacture  to 
carry  the  dj'^e  into  solution.  As  most  of  the  sulphur  dyes,  however,  at  the 
present  time  are  purified  in  manufacture  by  precipitation  of  the  solution  of 
the  crude  dye  with  sulphuric  acid  practically  all  of  the  sodium  sulphide  is 
eliminated  from  the  dycstuff.*  By  this  means  much  more  concentrated 
dyes  may  be  obtained,  and  furthermore  the  clj^es  will  keep  much  better, 
as  they  are  not  so  deliquescent  as  when  sodium  sulphide  is  present/^  Whether 

the  sodium  sulphide  acts  as  a 
reducing  agent  and  reduces  the 
dyestuff  to  a  soluble  leuco-dcriv- 
ative,  or  whether  it  acts  merely 
as  a  solvent  on  the  dyestuff,  or 
still  further,  whether  it  combines 
with  the  dyestuff  to  form  a  sol- 
uble compound,  are  all  questions 
which  have  not  yet  been  satis- 
factorily answered.  Xhere  arc 
points  which  may  be  brought 
forward  in  favor  of  each  one  of 
these  propositions.  Sodium  sul- 
phide, we  know,  is  a  rather 
strong  reducing  agent,  and  ap- 
parently the  coloring  matter 
may  be  precipitated  from  solu- 
tion in  many  cases  by  simple  oxidation  with  air.  ■  In  the  case  of 
certain  blue  sulphur  dyes,  for  instance,  there  seems  to  be  fittle  or  no 
question  as  to  the  formation  of  a  reduced  leuco-body,  for  the  color  of  the 
dissolved  dye  is  not  the  same  color  as  the  dyestuff — instead  of  being  blue  it 
is  yellow  or  greenish,  somewhat  resembling  the  appearance  of  reduced 
indigo  in  an  indigo  vat.  Furthermore,  many  of  the  sulphur  dyes  may  be 
brought  into  solution  with  sodium  sulphite  f  or  sodium  hydrosulphite, 
in  which  case  there  is  scarcely  any  doubt  as  to  the  formation  of  a  reduced 

*  The  yellow  sulphur  dyes  are  the  most  insoluble  of  this  class  of  colors  and  hence  care 
should  be  taken  in  dissolving  thorn,  or  the  true  value  of  the  dyestuff  will  be  lost  in  dyeing. 
Only  concentrated  sodium  sulphide  should  be  used  with  the  Sulphur  Yellows,  and  the 
best  method  for  dissolving  these  dyes  is  to  first  stir  them  up  into  a  paste  with  their  own 
weight  of  caustic  soda,  and  then  to  add  the  sulphide  and  hot  water. 

t  According  to  a  patent  of  the  Berlin  Aniline  Works  the  dyestuff  is  brought  into  solu- 
tion by  the  use  of  neutral  sodium  sulphite  in  the  presence  of  caustic  soda  and  glucose. 
This  solution  is  not  recommended  for  use  in  dyeing,  but  for  printing. 


Fig. 


193. — Dyeing  on  Bent  Sticks  for 
Sulphur  Dyes. 


DISSOLVING  SULPHUR  DYES 


377 


soluble  leuco-derivative.     In  the  case  of  the  black  and  brown  dyes,  how- 
ever, this  reduction  to  a  leuco-compound  is  not  so  apparent. 

On  the  other  hand,  in  the  case  of  Sulphur  Black,  for  instance,  the  color 
is  taken  up  by  the  fiber  from  solution  in  practically  the  same  manner  as  a 
substantive  dye,  and  there  seems  to  be  little  or  no  oxidation  required 
for  the  development  of  the  color,  and  the  dyestuff  appears  to  act  in  this 
case  as  if  it  were  simply  dissolved  as  such  in  the  sodium  sulphide.  The 
third  possibility  of  the  dyestuff  combining  with  the  sodium  sulphide  receives 
some  measure  of  support  in  that  the  dye  is  precipitated  from  solution  by 
the  addition  of  acid;  but  this  feature  may  also  be  explained  by  the  acid 
neutralizing  the  alkali  in  which  the  dye  is  dissolved,  without  any  special 
necessity,  of  the  dye  forming  a  compound  with  the  sodium  sulphide  or  not. 


Fig.  194. — Large  Size  Squeezer  for  Skein  Yarns. 


The  exact  chemistry  of  this  entire  matter  is  yet  to  be  worked  out,  as 
nothuig  very  definite  has  been  determined. 

The  sulphur  dyes  are  best  dissolved  in  iron  or  wooden  vessels  by  pour- 
ing over  them  hot  water  containing  a  part  of  the  sodium  sulphide  required 
for  the  dyeing.  The  dyebaths  should  be  of  wood,  and  all  the  metallic 
pipes  and  fittings  should  be  of  iron  or  lead,  copper  and  brass  being  avoided 
as  much  as  possible,  as  these  have  a  bad  effect  on  the  dyes.1( 

3.  Method  of  Dyeing. — The  sulphur  colors  are  mostly  dyed  in  a  bath 
containing  sodium  sulphide,  soda  ash,  common  salt,  and  many  of  them 
may  be  after-treated  with  chrome  or  bluestone  with  considerable  improve- 

*  It  should  also  be  noted  that  the  dyed  goods  before  being  rinsed  free  from  the  dye 
liquor  should  not  come  in  contact  with  copper  or  brass;  after  washing,  however,  contact 
with  these  metals  has  no  effect  on  the  color. 


378  SULPHUR  DYES 

ment  as  to  their  fastness.  The  sodium  sulphide  is  for  the  purpose  of 
dissolving  and  in  some  cases  of  reducing  the  dyestuff  (in  the  case  of  certain 
blue  dyes) ;  the  soda  ash  is  for  the  purpose  of  correcting  the  hardness  of  the 
\vater  and  making  the  bath  alkaline,*  as  the  dyes  appear  to  work  better 
in  an  alkaline  bath;  the  salt  is  added  as  with  ordinary  substantive  dyes, 
for  the  purpose  of  obtaining  a  better  exhaustion  of  the  dyebath.  In  some 
cases  the  dyestuff  itself  contains  sufficient  sodium  sulphide  to  dissolve  it 
in  the  bath,  and  consequently  none  need  be  addeds/.  The  sulphur  dyes  are 
evidently  not  as  yet  distinct  chemical  bodies;  that  is  to  say,  the  proper 
tinctorial  principle  in  many  cases  has  not  been  isolated  from  contaminating 
by-products  in  their  manufacture,  and  consequently  it  often  takes  a  rela- 
tively large  amount  of  dyestuff  to  obtain  a  full  shade;  from  10  to  15  per 
cent,  as  a  rule,  in  the  case  of  colors;  though  in  the  case  of  blacks,  the  color 
is  now  generally  purified  and  concentrated  so  that  a  full  shade  is  obtained 
with  4|  to  6  per  cent  (standing  bath)  of  dyestuff.  In  this  respect,  however, 
these  dj-es  are  constantly  being  improved,  as  better  methods  of  manufac- 
ture are  devised.  At  first,  sulphur  dyes  were  sold  usually  in  the  form  of 
irregular  lumps  which  rapidly  deteriorated  on  exposure  to  air  and  damp- 
ness t  with  liberation  of  sulphuretted  hydrogen;  but  in  this  respect  there 
has  been  much  improvement  of  late  by  selling  the  dyes  in  dry  powder  form. 
The  sulphur  dyes  exhaust  badly  and  require  a  large  amount  of  salt  in  the 
bath  where  heavy  shades  are  to  be  dyed.J  On  this  account  the  dyebath 
should  be  used  as  "  short  "  as  possible.  The  quantity  of  liquor  will  nat- 
urally vary  with  the  character  of  the  machine  in  which  the  dyeing 
operation  is  carried  out,  but  in  general  it  may  be  stated  that  when  dyeing 
loose  cotton  or  yarn  in  an  ordinary  dye-vessel  the  proportion  of  liquor 
should  be  from  1  :  20  to  1  :  30,  while  in  dj-eing  cops  and  tubes  in  special 
forms  of  dj^eing  apparatus  the  proportion  of  the  cotton  to  the  dye  liquor 

*  In  some  cases,  soda  ash  may  be  substituted  in  part  or  entirely  with  caustic  soda. 
In  the  dyeing;  of  Sulphur  Black  the  addition  of  a  small  amount  of  caustic  soda  is  recom- 
mended (one-tenth  of  the  weight  of  the  dyestuff)  in  order  to  prevent  the  development  of 
sulphuretted  hydrogen  gas,  the  odor  of  which  is  very  disagreeable  and  poisonous.  This 
addition  of  caustic  soda  is  usually  made  in  dissolving  the  dyestuff.  Care  should  be  had 
not  to  add  too  much  caustic  soda,  as  otherwise  the  dyeings  will  show  a  brownish  tone. 

t  On  account  of  the  hygroscopic  nature  of  the  sulphur  dyes,  they  should  always  be 
stored  in  a  dry  place  and  protected  as  far  as  possible  from  moisture. 

J  An  interesting  method  for  the  dyeing  of  Sulphur  Black  has  been  suggested  by  the 
Badische  Co.  A  cold  fermentation  vat  somewhat  after  the  manner  of  Indigo  is  em- 
ployed. The  vat  is  filled  with  60  gallons  of  cold  water  and  then  set  with  8  lbs.  of  wheat  or 
potato  flour,  6  lbs.  of  bran,  2  lbs.  of  syrup  or  honey,  and  2  lbs.  of  soda  ash.  From  5  to  7 
lbs.  of  Sulphur  Black  are  added  per  100  gallons  of  dye  liquor.  The  following  additions 
must  be  made  to  the  vat  from  time  to  time:  3  lbs.  of  dyestuff,  5  lb.  flour,  ^  lb.  of  bran, 
and  §  lb.  of  sjTup.  After  three  to  four  days  the  vat  will  be  perfectly  clear,  of  a  greenish 
color  and  ready  to  use.  The  vat  liquor  should  always  produce  a  red  color  with  phe- 
nolphthalein  paper,  and  the  dyebath  should  be  used  as  short  as  possible. 


TENDERING   EFFECT  ON   COTTON 


379 


may  be  from  1  :  5  to  1  :  10.  In  dyeing  cloth  in  jiggers  the  proportion  of 
liquor  will  also  be  quite  low  (about  1:5.)  In  the  use  of  short  baths, 
however,  care  must  always  be  exercised  not  to  have  the  liquor  so  highly 
concentrated  as  to  throw  the  dye  and  the  various  salts  out  of  solution. 
In  order  to  avoid  the  dilution  of  the  dyebath  during  the  dyeing  and  the 
heating  up  of  successive  baths  it  is  advisable  to  use  closed  steam  pipes 
instead  of  live  steam  for  purposes  of  heating. 

v€)ne  of  the  drawbacks  to  the  use  of  the  sulphur  dyes  has  been  their 
recognized  liability  to  cause  a  tendering  of  the  fiber,  which  is  slow  in  devel- 
opment and  often  does  not  become  evident  until  some  months  after  the 
goods  have  been  dyed.     Recent  researches  on  this  subject  have  shown  that 


Fig.  195. — Steam  Vat  for  Developing  Sulphur  Colors  on  Skein  Yarn. 


the  tendering  is  caused  by  the  development  of  free  sulphuric  acid  in 
the  goods,  and  furthermore  that  this  acid  is  not  derived  from  sodium  sul- 
phide left  in  the  fiber,  but  is  formed  by  the  oxidation  of  the  color-molecule 
itself.*  In  order  to  prevent  this  tendering  action  it  has  been  suggested 
to  treat  the  dyed  goods  with  tannic  acid  (1  per  cent)  and  lime  water,  thus 
forming  tannate  of  lime  in  the  fiber,  f  This  is  insoluble  in  water  and  pos- 
sesses the  ability  to  neutralize  the  free  sulphuric  acid  as  fast  as  formed. 
Actual  tests  have  shown  that  this  treatment  is  very  efficacious. 

Tendering  in  the  case  of  goods  dyed  with  Sulphur  Black  may  arise  in 
union  goods  where  the  warp  is  dyed  with  Sulphur  Black  and  the  cloth  is 
subjected  to  a  "  stoving  "  operation  for  the  purpose  of  bleaching  the  wool 

*  See  Pilling,  Jo^ir.  Dyers  and  Col,  1906,  p.  5-1;  Vlies,  ibid.,  1910,  p.  79. 
t  See  Holden,  Jour.  Soc.  Dyers  and  Col.,  1910,  p.  76. 


380  SULPHUR  DYES 

or  of  brightening  the  color  dyed  on  the  wool.  For  such  goods  suitable 
direct  cotton  colors  should  be  used  in  place  of  sulphur  dyes.  /03tton 
goods  d\'ed  with  Sulphur  Black  may  also  show  tendering  if  after-treated 
with  bluestone.  Such  an  after-treatment  is  sometimes  practiced  in  order 
to  improve  the  shade  of  the  black.  After-treatment  with  chrome,  on  the 
other  hand,  reduces  the  danger  of  tendering  in  Sulphur  Blacks.  "To  test  a 
dyeing  of  Sulphur  Black  for  liability  to  tender,  heat  the  sample  in  an  oven 
for  one  hour  at  280°  F.  (140°  C.)  then  expose  to  the  atmosphere  until  the 
cotton  regains  its  natural  moisture.  Carry  out  a  blank  test  on  undyed 
cotton  and  then  compare  the  samples  for  strength.  The  tendering  of 
cotton  dyed  with  Sulphur  Black  is  due  to  the  formation  of  sulphuric  acid  in 
the  fiber,  but  this  acid  is  not  derived  from  the  free  sulphur  which  may  have 
become  attached  to  the  fiber,  as  is  very  generally  supposed.  Ziinker  has 
shown  that  the  sulphuric  acid  is  derived  from  the  sulphur  combined  con- 
stitutionally in  the  dye.  All  of  the  sulphur  existing  as  a  component  part 
of  the  dye,  however,  is  not  convertible  into  acid,  but  only  a  relatively 
small  proportion.  The  presence  of  any  heavy  metals  (such  as  iron)  in  the 
dye  will  cause  the  formation  of  acid  very  quickly. 

The  sodium  sulphide  in  the  bath  should  be  sufficient  thoroughly  to  dis- 
solve all  the  dyestuff  so  that  the  bath  is  clear;  if  the  bath  is  turbid,  more 
sodium  sulphide  should  be  added.  Usually  the  amount  of  sodium  sulphide 
required  is  equal  to  that  of  the  dyestuff,  though  in  cases  of  highly  concen- 
trated dyes  and  blacks,  this  quantity  may  need  to  be  considerably  increased. 
Insufficient  sodium  sulphide  will  leave  undissolved  dyestuff  in  the  bath, 
and  cotton  dyed  under  such  conditions  will  be  coated  with  a  loosely  adhe- 
rent layer  of  dyestuff,  which  will  subsequently  wash  off  or  crock,  while 
the  color  will  usually  show  uneven  streaks  or  bronziness.* 

VProbably  the  chief  defect  which  arises  in  the  dyeing  of  Sulphur  Blacks 
on  cotton  is  the  bronzing  of  the  color.  The  bronziness  may  be  removed 
in  most  cases  by  treating  the  dyed  goods  in  a  bath  containing  an  emulsion 
of  oil.  Olive  oil  with  soda  and  some  soap  may  be  used  for  this  purpose, 
or  the  following  has  also  been  recommended:  melt  100  lbs.  of  palm-oil  in 

*  Bronziness  in  the  dyeing  of  Sulphur  Black  may  be  due  to  several  causes:  (1) 
The  use  of  too  much  salt  in  the  bath;  this  may  readily  be  corrected  by  properly  diluting 
the  bath  with  water.  (2)  The  use  of  too  much  dyestuff  causing  an  overloading  of  the 
fiber  with  color.  (3)  The  use  of  too  little  sodium  sulphide,  thus  allowing  the  dye  to 
come  out  of  solution  too  readily.  A  few  drops  of  the  dyebath  placed  on  filter  paper 
should  show  no  undissolved  sediment.  (4)  Undue  exposure  of  the  material  to  the  air 
during  dyeing,  or  by  allowing  the  dyed  goods  to  lie  or  hang  some  time  before  being 
rinsed.  (5)  Incomplete  rinsing  after  dyeing;  if  the  rinsing  is  complete  the  last  wash 
waters  should  flow  off  clear.  If  bronziness  develops  on  the  dyed  cotton  from  whatever 
cause,  it  may  be  removed  by  passing  the  goods  through  a  weak  warm  bath  of  sodium 
sulphide,  which  has  the  effect  of  dissolving  off  the  outer  layer  of  unfixed  dyestuff  which 
causes  the  bronziness.  This  sodium  sulphide  wash  should  be  very  dilute,  as  otherwise 
so  much  color  may  be  removed  that  the  black  will  dry  up  thin  and  slaty. 


DENSITY  OF   DYEBATH  381 

an  iron  pan,  add  12  lbs.  of  caustic  soda  (90°  Tw.),  stir  the  mixture  and  allow 
to  stand  overnight;  10  per  cent  of  this  emulsion  is  used  on  the  cotton  in  a 
bath  at  140°  F.  Not  only  will  the  bronziness  be  removed  but  the  handle  of 
the  cotton  will  also  be  made  much  softer.  In  order  to  test  the  condition  of 
the  bath  some  of  the  liquor  should  be  dropped  on  a  piece  of  white  blotting 
paper,  when  if  a  perceptible  precipitation  is  shown,  more  sodium  sulphide 
should  be  added  until  the  bath  is  brought  to  the  proper  condition.  If 
sodium  sulphide  crystals  are  employed  instead  of  the  fused  sodium  sul- 
phide, just  about  twice  the  quantity  must  be  used,  as  the  crystals  contain 
a  large  amount  of  water  of  crystallization.  The  amount  of  sodium  sul- 
phide to  be  added  to  the  bath  will  also  vary  with  the  character  of  apparatus 
employed  in  dyeing.  In  open  dye-vessels,  such  as  vats  and  jiggers,  per- 
mitting free  access  of  air,  it  will  be  necessary  to  use  about  twice  as  much 
sodium  sulphide  as  dyestuff,  whereas  in  dyeing  machines  of  the  closed  type 
where  there  is  little  or  no  access  of  air,  the  amount  of  sodium  sulphide 
may  be  reduced  to  a  weight  equal  to  that  of  the  dyestuff  used. 

iJnnecessarj^  boiling  of  the  dyebath  should  be  avoided,  as  this  causes 
the  oxidation  of  the  sulphide  to  too  great  an  extent;  if  there  is  too  much 
sodium  sulphide  present,  on  the  other  hand,  the  cotton  will  not  take  up 
the  color  well  and  the  dyeings  will  appear  thin.  In  place  of  using  common 
salt,  glaubersalt  may  be  used  with  like  effect.  In  order  to  control  the 
amounts  of  salts  which  are  present  in  standing  kettles,  it  is  best  to  use 
hydrometer  tests;  for  blacks  the  cold  dj-e  liquor  should  stand  at  8  to  10° 
Tw.  at  60°  F.,  but  for  blues  and  other  colors  it  should  not  exceed  4  to  5° 
Tw.  It  should  be  borne  in  mind  that  10  parts  of  common  salt  are  equiva- 
lent to  12  parts  of  calcined  glaubersalt  or  to  24  parts  of  the  crystallized 
glaubersalt.*/ 

As  the  dyebaths  with  sulphur  colors  exhaust  but  poorly  they  are  usually 
preserved  as  standing  kettles,  when  only  about  two-thirds  of  the  original 
amount  of  dye  need  be  added  to  the  second  bath  to  produce  the  same 

*  The  amount  of  salts  added  should  really  be  based  on  the  volume  of  dye  liquor 
rather  than  upon  the  weight  of  the  cotton  being  dyed.  The  following  table  shows  the 
relative  amounts: 


Proportion  of  Liquor. 

Pounds  per  100  Gallons  of  Liquor. 

Glaubersalt  (crystallized) 

Common  Salt. 

1  :  5 
1  :  10  to  1  :  15 
1  :  20  to  1  :  30 

20-25 

20-50 

100-120 

8-10 

8-20 

40-50 

When  the  dyeing  is  carried  out  in  a  mechanical  apparatus  in  which  the  material  is  closely 
packed  and  a  concentrated  dye  liquor  is  used,  it  is  best  to  employ  glaubersalt  rather 
than  common  salt,  as  the  former  is  more  soluble. 


382  SULPHUR  DYES 

shade.  The  amount  of  dyestuff  to  be  added  usually  has  to  be  adjusted  till 
the  third  or  fourth  bath,  when  it  becomes  constant.*  A  proportional 
amount  of  sodium  sulphide  has  to  be  added  with  the  dyestuff.  As  a  rule, 
the  sulphur  dyebaths  do  not  deteriorate  to  any  extent  on  standing.  The 
sodium  sulphide  contained  in  the  liquor  is  gradually  oxidized  to  sodium 
sulphate  (glaubersalt)  on  prolonged  exposure  to  the  air,  and  the  coloring 
matter  in  consequence  becomes  precipitated;!  but  this  may  easily  be 
remedied  and  the  bath  brought  back  to  its  useful  condition  again  by 
boiling  up  and  adding  a  fresh  amount  of  sodium  sulphide,  t 

When  dyebaths  of  Sulphur  Black  remain  used  for  some  length  of  time, 
the  sodium  sulphide  will  become  more  or  less  completely  oxidized  by  the 
air;  and  consequently  on  bringing  the  l>ath  into  use  again  it  will  be  neces- 
sar>'  to  use  considerably  more  sodium  sulphide  than  would  at  first  be  indi- 
cated. Under  such  circumstances  the  liquor  of  the  bath  should  always  be 
tested  with  a  piece  of  filter  paper  to  see  if  the  dj'estuff  is  in  proper  solution. § 

The  length  of  time  a  standing  bath  may  be  used  with  Sulphur  Black 

*  The  quantity  of  dyestuff  to  be  added  to  the  second  bath  for  the  production  of  a 
certain  depth  of  color  is  about  one-half  to  two-thirds  that  originalh'  taken  for  the  first 
bath.  The  quantity  of  sodium  sulphide  to  be  added,  however,  is  not  necessarily  in  the 
same  proportion,  as  this  is  not  taken  up  by  the  fiber  from  the  dyebath  in  the  same  ratio 
as  the  dyestuff,  but  to  a  less  degree.  On  the  other  hand,  more  or  less  of  the  sodium  sul- 
phide is  oxidized  in  the  bath  to  sodium  sulphate.  Therefore  the  proper  amount  of 
sodium  sulphide  to  be  added  must  be  governed  by  the  amount  required  to  bring  the 
dyestuff  in  the  bath  to  a  condition  of  good  solution.  The  amount  of  salt  and  soda 
taken  up  from  the  bath  by  the  fiber  is  also  much  less  than  that  of  the  dyestuff,  therefore 
the  quantities  of  these  to  be  added  are  relatively  small,  and  are  to  be  governed  by  the 
density  of  the  bath,  as  already  pointed  out. 

t  Frequently  when  dj'eing  Sulphur  Blacks  a  white  scum  of  finely  divided  sulphur 
will  collect  on  the  surface  of  the  dyebath  and  become  attached  to  the  cotton,  leaving  a 
white  mark.     This  defect  may  be  remedied  by  adding  sodium  sulphite  to  the  dyebath. 

t  Almost  perfect  exhaustion  may  be  obtained  in  dyeing  with  sulphur  dyes  by  adding 
5  per  cent  of  ammonium  sulphate  to  the  bath  towards  the  end  of  the  dyeing  and  boiling 
fifteen  minutes  longer  (see  Whittaker,  Dyer  and  Calico  Printer,  1916,  p.  50).  This 
action  may  be  illustrated  by  the  following  test:  Prepare  two  dj-ebaths  (a)  18  per  cent 
Sulphur  Black,  18  per  cent  sodium  sulphide,  5  per  cent  soda  ash  and  60  per  cent  salt; 
(fc)  12  per  cent  Sulphur  Black,  12  per  cent  sodium  sulphide,  .5  per  cent  soda  ash  and  60 
per  cent  salt.  Enter  the  yarn  into  the  boiling  dyebath,  work  one-half  hour,  then  add 
5  per  cent  ammonium  sulphate  to  bath  (b)  and  continue  boiling  for  fifteen  minutes.  It 
will  be  found  that  both  dyeings  will  have  about  equal  depth  of  shade,  showing  that  the 
second  bath  is  completely  exhausted.  The  explanation  of  this  action  is  that  the  ammo- 
nium sulphate  is  decomposed  with  gradual  liberation  of  acid  that  throws  out  the  dye- 
stuff  on  the  fiber. 

§  In  the  dyeing  of  cotton  piece-goods  with  Sulphur  Black  in  the  jigger  it  is  not  recom- 
mended to  add  salt  to  the  bath,  as  this  is  liable  to  redden  the  shade  and  there  is  also  a 
tendency  of  the  selvedge  to  come  up  bronzy.  In  dyeing  cotton  pieces  with  a  worsted 
border  with  Sulphur  Black  the  dyebath  must  be  cold  to  leave  the  wool  white,  also 
glue  is  added  to  the  bath  to  prevent  the  wool  from  being  injured  by  the  alkali  present 
(about  1  per  cent  of  glue  is  added  to  the  first  bath). 


TEMPERATURE   OF   DYEBATH  383 

will  depend  a  good  deal  on  the  quantity  and  character  of  the  impurities 
constantly  being  introduced.  If  good  soft  water  is  employed  and  if  the 
cotton  is  boiled  out  before  coming  into  the  dyebath,  the  latter  may  be 
used  at  times  for  months  before  it  is  necessary  to  discard  it.  If,  however, 
dirty  or  hard  water  is  used  and  if  the  raw  cotton  is  introduced  directly 
into  the  bath  a  large  amount  of  impurities  will  collect  in  the  liquor  and  it 
will  soon  be  rendered  unfit  for  use.  Before  running  off  an  old  bath,  how- 
ever, the  dyestuff  may  be  saved  from  it  by  passing  through  it  several 
batches  of  goods  without  further  addition  of  dyestuff,  then  bringing  these 
batches  up  to  shade  in  the  fresh  bath.* 

In  special  cases  glucose,  dextrin  and  Turkey-red  oil  are  added  to  the 
bath  in  order  to  secure  better  exhaustion  and  better  penetration  of  the 
goods,  t  In  nearly  all  cases  the  sulphur  dyes  may  be  dyed  in  a  boiling  bath, 
though  just  under  the  boil  is  a  better  practice;  in  the  case  of  some  blue 
dyes,  the  temperature  of  the  bath  should  not  be  over  85°  F.  The  sulphur 
colors  may  also  be  dyed  very  well  in  lukewarm  or  even  cold  baths.  After 
dyeing  it  is  important  that  the  goods  be  well  squeezed  and  thoroughly 
rinsed  immediately  after  coming  from  the  dyebath,  in  order  to  prevent 
the  precipitation  of  unfixed  dyestuff  superficially  on  the  fiber;  this  rinsing 
gives  rise  to  more  even  shades  and  the  colors  are  faster  to  rubbing.  | 

*  Besides  the  ordinary  form  of  Sulphur  Black  in  powder,  this  dye  is  also  marketed 
in  the  form  of  a  paste,  in  which  case  it  will  usually  contain  about  40  per  cent  of  solid 
dyestuff.  It  will,  however,  show  a  greater  strength  than  this  when  compared  with 
the  dry  powder,  and  will  also  show  much  less  acidity  and  less  content  of  iron.  This  is 
due  to  the  fact  that  in  drying  Sulphur  Black,  unless  very  special  precautions  are  taken, 
some  of  the  tinctorial  strength  of  the  dye  will  be  lost  and  a  considerable  quantity  of 
acid  (presumably  sulphuric  acid  or  a  bisulphate  salt)  is  also  formed  in  the  drying.  This 
latter  dissolves  some  iron  from  the  pans,  etc.,  which  thus  gets  into  the  dyestuff.  In 
order  to  prevent  the  formation  of  acid  in  the  paste  dye  it  is  customary  to  add  a  small 
quantity  of  soda  ash  directly  to  the  paste  (and  the  same  can  be  done  in  the  preparation 
of  the  dry  powder).  The  paste,  though  possessing  these  better  features,  is  not  gener- 
ally favored  by  the  dyers,  as  it  will  be  continually  drying  out  and  thus  changing  in 
strength  unless  used  up  very  shortly  after  the  container  is  opened.  Furthermore,  the 
proportion  of  freight  expense  is  higher  on  account  of  the  water  content  of  the  paste.  On 
the  other  hand,  the  cost  of  manufacture  of  the  paste  is  less  per  unit  of  color  than  the 
powder. 

Sulphur  Black  has  also  been  marketed  in  the  form  of  a  liquid  (as  in  Thiogene  Black 
Liquid  M,  of  Hochst)  which  consists  of  the  reduced  coloring  matter  in  solution  ready  for 
use  in  dyeing.  A  50  per  cent  solution  was  generally  made,  and  this  required  only  one- 
third  the  usual  amount  of  sodium  sulphide  to  be  added  to  the  bath.  This  form  of  Sul- 
phur Black  was  especially  recommended  for  dyeing  by  the  padding  method. 

t  These  additions  are  seldom  made  except  when  heavy  yarns  or  closely  woven  goods 
are  being  dyed. 

X  As  the  Liquor  in  the  goods  contains  considerable  dyestuff  this  should  be  squeezed 
back  into  the  bath  for  the  sake  of  economy.  The  first  rinsing  bath  will  also  contain 
quite  a  lot  of  dyestuff,  and  this  hquor  may  be  used  for  freshening  up  the  old  dyebath 
or  for  the  solution  of  the  next  addition  of  coloring  matter.     If  a  small  proportion  of 


384 


SULPHUR  DYES 


Fig.  196. — Iron   Dyeing   Machine  for  Sul- 
phur Colors.      (Klauder-Weldon  Dyeing 

Machine  Co.) 


With  some  of  the  blues  it  is  necessary  to  oxidize  the  color  after  dyeing; 
this  may  be  done  by  squeezing  and  hanging  in  the  air,  or  by  steaming  in 

the  air,  or  bj'-  after-treating  with  a 
solution  containing  a  small  amount 
of  chrome  or  sodium  peroxide. 
Some  of  the  Sulphur  Blues,  how- 
ever, dj'e  direct  without  any  after- 
treatment.* 

Owing  to  the  strong  alkalinity  of 
the  sulphur  dyebath,  caution  should 
be  used  not  to  get  the  liquor  on  the 
hands  or  skin  of  the  workmen.  In 
handling  the  goods  the  hands  should 
be  protected  with  rubber  gloves. 

In  dyeing  j-arn  in  the  open  vat  on 
sticks,  if  the  goods  are  simply  lifted 
out  of  the  dyevat  and  hung  up  to 
drain,  there  will  be  so  much  dye 
liquor  in  the  yarn  that  the  dye  is  liable  to  oxidize  and  show  up  bronzy  on  the 
goods.  On  the  other  hand,  if  the  yarn  is  not  allowed  to  drain  but  is  washed 
off  immediately  a  larger  amount  of  dye  liquor  will  be  lost  in  the  wash 
waters.  In  order  to  overcome  these  undesirable  features  it  is  necessary 
to  wring  or  squeeze  the  yarn  as  it  is  taken  from  the  vat.     To  do  this  by 

sodium  sulphide  is  used  in  the  first  rinsing  bath,  the  goods  will  be  more  thoroughly 
cleansed  of  any  unfixed  particles  of  coloring  matter,  and  consequently  will  exhibit  a 
greater  degree  of  fastness  to  crocking. 

*  The  after-treatment  by  steaming  for  the  purpose  of  developing  the  proper  color  of 
certain  of  the  blue  sulphur  dyes  may  be  conveniently  carried  out  on  skein  yarn  bj' 
hanging  the  hanks  in  an  empty  vat,  and  rather  than  employ  the  dj'evat  itself  it  is  best 
to  use  one  that  has  been  specially  arranged  for  this  purpose.  The  vat  should  be  fitted 
with  a  perforated  false  bottom  and  with  a  roof-shaped  lid  covered  on  the  inside  with 
cloth.  This  is  done  in  order  to  prevent  the  condense  water  from  dripping  on  the  goods, 
as  the  dyeings  will  not  develop  where  drops  of  water  fall  on  the  material.  The  steam 
pipe  carries  an  air  injector  so  that  the  steaming  treatment  is  accomplished  with  a  mixture 
of  steam  and  air  at  a  temperature  of  180  to  200°  F.  The  perforations  in  the  steam  pipe 
should  be  in  an  oblique  downward  direction  so  that  the  steam  does  not  blow  directly  on 
to  the  goods  (see  Fig.  195).  Cloth  may  be  steamed  by  folding  it  up  loosely  in  the  moist 
condition  and  leaving  it  in  a  room  at  175°  F.  for  several  hours.  During  the  steaming  of 
the  sulphur  dyes  it  is  necessary  that  the  goods  contam  some  caustic  soda  and  sodium 
sulphide;  on  this  account  it  is  best  not  to  rinse  the  goods  before  steaming.  If  the 
goods  are  washed  after  dyeing,  before  being  placed  in  the  steam  box  they  should  be 
passed  through  a  bath  containing  j  oz.  of  caustic  soda  and  1  oz.  of  sodium  sulphide  per 
gallon.  In  some  cases,  instead  of  steaming  the  development  may  be  satisfactorily  accom- 
plished by  squeezing  the  yarn  out  evenly  then  hanging  it  up  on  sticks  and  exposing  it  to 
the  air  at  the  ordinary  temperature  for  several  hours.  In  the  case  of  warps  and  loose 
cotton  the  goods  are  simply  allowed  to  lie  in  the  warm  moist  condition  until  properly 
oxidized. 


VAT   DYEING   WITH  SULPHUR  COLORS  385 

hand  is  both  inconvenient  and  harmful  to  the  workmen  as  the  sodium 
sulphide  liquor  is  quite  corrosive  to  the  hands  and  skin.  It  is  best  to 
have  the  dyevat  provided  with  a  yarn  wringer  through  which  the  skeins 
are  passed  before  being  rinsed.  It  should  be  so  arranged  that  the  dye 
liquor  that  is  squeezed  out  runs  back  into  the  bath.  If  it  is  not  feasible  to 
squeeze  the  yarn  in  this  manner,  the  hanks  should  be  put  in  a  centrifugal 
hydro-extractor  and  the  excess  liquid  removed.  The  yarn  may  then  be 
washed  in  the  hydro-extractor  before  being  removed. 

Many  of  the  sulphur  dyes  resemble  the  vat  colors  in  that  they  may  be 
reduced  to  a  soluble  leuco-compound  by  the  action  of  reducing  agents  in 
the  presence  of  strong  alkaline  solutions.  Under  these  circumstances 
they  may  be  used  practically  as  vat  dyes,  similar  to  Indigo  or  the  indan- 
threne  colors.  This  process,  so  far,  has  been  but  slightly  studied  and  its 
practical  feasibility  has  not  been  thoroughly  established.  According  to 
Ganswindt  (Theorie  und  Praxis  der  modernen  Farherei,  p.  306)  the  only 
form  of  this  process  which  has  been  discussed  is  the  glucose-caustic  soda 
vat.  It  may  be  prepared  as  follows:  Sulphur  Black  (or  Sulphur  Blue),  for 
example,  is  mixed  with  an  equal  weight  of  caustic  soda  (40°  Be.)  which  has 
been  previously  diluted  with  an  equal  volume  of  water;  then  an  equal 
weight  of  glucose  is  added,  and  the  mixture  heated,  when  a  complete  reduc- 
tion and  solution  will  result.  This  liquor  furnishes  the  "  stock-vat  "  and 
is  added  in  the  desired  amount  to  the  dyebath,  which  is  made  up  with  com- 
mon salt  and  neutral  sodium  sulphite.  It  is  even  said  that  in  this  manner 
the  sulphur  dyes  may  be  applied  in  connection  with  Indigo  in  the  same  vat. 
According  to  a  French  patent  of  the  Hochst  Co.  better  results  can  be 
obtained  by  the  use  of  hydrosulphite  as  the  reducing  agent.  In  this  case 
the  dyestuff  is  mixed  with  fifteen  times  its  weight  of  hydrosulphite  solu- 
tion (13°  Be.)  at  a  temperature  of  140°  F.  This  furnishes  the  stock-vat 
and  may  be  used  in  a  manner  similar  to  that  described  above.* 

*  An  English  process  patented  by  Lodge-Evans  for  the  use  of  sulphur  dyes  in  a 
reduced  form  in  a  vat  is  of  interest.  The  process  was  devised  chiefly  for  the  applica- 
tion of  sulphur  dyes  in  union  dyeing,  garment  dyeing  and  the  dyeing  of  delicate  fibers, 
such  as  artificial  silk,  which  will  not  stand  the  action  of  a  boiling  bath  of  sodium  sulphide. 
The  process  depends  on  the  dissolving  of  the  dyestuff  in  a  solution  of  sodium  sulphite; 
this  gives  a  perfect  solution  of  the  leuco-compound,  which,  however,  has  no  dyeing 
properties.  The  addition  of  ammonium  sulphide  or  sodium  hydrosulphite  to  this  solu- 
tion brings  it  to  a  condition  in  which  it  will  dye  the  various  fibers  satisfactorily. 

The  preparation  of  the  ammonium  sulphide  vat  is  carried  out  as  follows:  Boil 
up  1  part  of  sulphur  dyestuff  with  2  parts  sodium  sulphite  (cryst.);  then  add  1  part 
sodium  sulphide  (cone.)  and  boil  until  solution  is  complete.  Cool  down  the  bath  and 
add  2  parts  ammonium  sulphate,  which  produces  ammonium  sulphide  and  sodium  sul- 
phate in  the  bath  by  double  decomposition.  The  ammonium  sulphide  is  used  as  it 
does  not  have  the  same  destructive  effect  as  sodium  sulphide  on  wool,  silk,  and  artificial 
silk. 

The  hydrosulphite  vat  is  prepared  as  follows:  Boil  up  1  part  of  the  sulphur  dye  with 


3K6  SULPHUR  DYES 

4.  After-treatment  of  Sulphur  Dyes. — The  depth  and  bloominess  of 
Sulphur  Blacks  may  be  considerably  improved  by  giving  the  cotton  an 
oil  finish  after  dyeing.*  An  olive-oil  emulsion  prepared  by  boiling  up  1 
pint  of  olive  oil  and  |  lb.  of  soda  ash  with  5  gallons  of  water  will  sei've  very 
well.  This  amount  of  emulsion  will  be  sufficient  for  treating  100  lbs.  of 
cotton.  A  lukewarm  bath  containing  a  small  quantity  (1  to  3  per  cent)  of 
soap  or  cotton  softener  may  also  be  used  for  brightening  the  color,  f 
This  treatment  also  serves  the  purpose  of  softening  the  goods,  which  are 
usually  made  rather  harsh  and  stiff  when  dyed  in  heavy  shades  with  the 
sulphur  colors.  J 

Dyeings  with  Sulphur  Black  will  usually  become  somewhat  bluer  after 
standing  for  a  short  time,  and  therefore  this  must  be  allowed  for  in  matching 
colors.  This  slight  change  in  tone  is  probably  due  to  oxidation.  It  usu- 
ally requires  a  few  days  to  effect  the  maximum  change  and  after  that 
the  color  is  permanent.     If  it  is  desired  to  bring  up  this  change  immediately, 

4  parts  sodium  sulphite  (cryst.)  until  complete  solution  is  obtained;  then  cool  the  liquor 
and  add  1  part  of  sodium  hydrosulphite  powder  (cone).  The  formaldehyde  or  zinc 
hydrosulphite  compounds  must  not  be  used. 

In  dyeing  with  these  baths  they  are  started  cold,  at  which  temperature  cotton  and 
artificial  silk  only  are  dyed.  If  union  goods  or  silk-cotton  material  is  to  be  dyed  the 
temperature  of  the  bath  must  be  raised  if  a  uniform  shade  on  both  fibers  is  desired. 
The  proper  temperature  varies  with  the  different  colors;  Sulphur  Black,  for  instance, 
dyes  well  at  150°  F.,  while  Sulphur  Blue,  Sulphur  Green,  Sulphur  Brown,  and  Sulphur 
Yellow  should  be  dyed  at  about  100°  F.  Even  with  these  conditions,  however,  the  wool 
and  silk  are  somewhat  tendered,  therefore  in  practice  the  process  will  doubtless  be  mostly 
limited  in  the  case  of  union  goods  to  the  dyeing  of  the  cotton  in  fast  colors  in  the  piece. 
In  dyeing  artificial  silk  the  hydrosulphite  bath  is  preferred,  as  the  color  goes  on  well  in  a 
cold  bath  without  injury  to  the  luster  and  strength  of  the  fiber. 

*  In  dyeing  mercerized  cotton  with  sulphur  dyes  it  will  generally  be  found  that 
the  fiber  has  lost  much  of  its  luster.  This  defect  may  be  somewhat  improved  by  an 
after-treatment  at  140°  F.  in  a  bath  containing  3  per  cent  of  soap  and  1  per  cent  of 
olive  oil  emulsified  with  ammonia. 

t  The  various  mixtures  suggested  for  the  purpose  of  softening  yarns  d3^ed  with  Sul- 
phur Blacks  include  the  following:  (1)  Use  3  per  cent  of  soft  soap  in  a  bath  at  about  200° 
F.  for  one-half  hour;  this  makes  the  shade  rather  fuller  and  bluer.     (2)  An  emulsion  of 

2  per  cent  of  soap  and  1  per  cent  of  olive  oil,  used  in  a  bath  at  140°  F.  for  one-half  hour 
will  also  make  the  shade  fuller  and  bluer.     (3)  An  emulsion  of  2  per  cent  of  soap  with 

3  per  cent  of  Turkey-red  oil,  used  in  a  bath  at  140°  F.  for  one-half  hour.  (4)  An  emulsion 
of  1  per  cent  of  soda  ash  with  1^  per  cent  of  olive  oil,  used  in  a  bath  at  140°  F.  for  one- 
half  hour.  (5)  An  emulsion  made  by  boiling  up  1  per  cent  of  starch  with  1  per  cent  of 
pressed  lard,  used  in  a  bath  at  120°  F.  for  one-half  hour;  this  will  deepen  the  black 
without  altering  its  tone. 

t  In  the  dyeing  of  Sulphur  Blacks  on  cotton  hosiery  it  is  sometimes  desirable  to  imi- 
tate the  peculiar  "  handle  "  of  Aniline  Black  dyeings.  In  order  to  accomplish  this  the 
cotton  may  be  treated  as  follows:  The  goods  after  dyeing  are  well  rinsed  and  then  treated 
with  a  hot  bath  containing  4  ozs.  of  soap  per  10  gallons;  lift,  drain,  and  then  treat  for  a 
short  time  in  a  lukewarm  bath  containing  6  ozs.  alum  and  G  ozs.  sodium  acetate  Der  10 
gallons,  then  hydro-e.xtract  and  dry. 


AFTER-TREATING   SULPHUR   DYES 


387 


the  dyeings  may  be  after- 
treated  for  half  an  hour  in 
a  fresh  bath  at  about  160° 
F.  with  3  per  cent  of  chrome 
and  5  per  cent  of  caustic 
soda. 

Some  of  the  sulphur 
dyes  require  to  be  fixed  or 
after-treated  with  metallic 
salts,  such  as  chrome  or 
bluestone.*  In  certain  cases 
this  after-treatment  is  nec- 
essary for  the  complete 
development  of  the  color, 
while  in  other  cases  it 
merely  increases  somewhat 
the  fastness  of  the  color  to 
light  and    washing,  f     The 

*  The  after-treatment  with 
bluestone  must  never  be  used 
with  Sulphur  Blacks  as  this  will 
cause  the  dyed  cotton  to  become 
tender. 

t  There  is  a  group  of  the 
sulphur  colors  known  as  the 
Melanogen  dyes  (  H  6  c  h  s  t ) 
which  is  somewhat  different 
from  the  usual  sulphur  colors  in 
that  the  direct  dyeings  have  no 
value,  but  require  to  be  after- 
treated  with  metallic  salts  in 
order  to  furnish  satisfactory 
shades.  It  is  supposed  that 
they  form  real  color-lakes  with 
the  metallic  compounds.  The 
Melanogen  for  black  is  dyed 
without  the  addition  of  sodium 
sulphide,  using  a  rather  con- 
centrated bath  with  the  addition 
of  2  to  5  per  cent  of  soda  ash 
and  4  ozs.  of  common  salt  for 
each  gallon  of  dye  liquor.  After 
dyeing  the  goods  are  rinsed  and 
after-treated  in  a  fresh  bath  with 
4  per  cent  of  copper  sulphate 
and  2  per  cent  of  acetic  acid  to 
give  a  jet  black,  or  with  4  per 


—  o3 


388 


SULPHUR  DYES 


after-treatment,  as  a  rule,  darkens  the  shade  and  dulls  the  color.  It 
is  carried  out  in  the  same  manner  as  for  substantive  dyes.  An  after- 
treatment  with  sodium  acetate  is  also  frequently  given  the  sulphur 
colors;  this  is  especially  so  with  the  brown  dj-es.  It  is  for  the  purpose 
of  neutralizing  the  excess  of  sodium  sulphide  in  the  fiber.  The  treat- 
ment usually  alters  the  shade  somewhat,  but  if  it  is  omitted  the  color 
of  the  dj'ed  cotton  will  generally  slowly  change  considerably  after  several 
weeks'  standing. 

The  sulphur  colors  may  be  stripped  to  a  certain  extent  (in  case  the 
color  goes  over  the  required  shade)  by  treating  with  a  hot  bath  containing 
sodium  sulphide  (3  to  10  ozs.  of  sodium  sulphide  per  10  gallons  of  water). 


Fig.  198. — Dyeing  Beams  with  Sulphur  Dyes.     (Pomitz.) 


Solutions  of  soap  and  soda  ash  have  but  little  effect  on  the  sulphur  dyes. 
If  a  greater  degree  of  stripping  is  desired,  solutions  of  bleaching  powder 
may  be  used. 

5.  Topping  of  Sulphur  Colors. — The  sulphur  colors  may  be  topped  with 
a  variety  of  dyes.  Like  the  general  class  of  substantive  colors  they  possess 
the  property  of  fixing  basic  dyes,  though  to  a  greater  extent.  The  fast- 
ness of  the  color  does  not  appear  to  be  much  impaired  by  the  topping,  pro- 
vided an  excess  of  basic  dye  is  not  employed.  The  amount  of  the  latter 
actually  fixed  is  about  0.2  to  0.4  per  cent,  and  this  is  sufficient  to  furnish 
good  bright  shades.     The  topping  is  carried  out  in  a  fresh  cold  bath  with 

cent  of  nickel  sulphate  and  acetic  acid  to  give  a  bluish  black,  or  with  4  per  cent  of 
zinc  sulphate  and  acetic  acid  to  give  a  violet  tone  black.  The  Melanogen  Blue  is 
dyed  and  developed  in  the  same  manner. 


TOPPING  WITH  OTHER  DYES  389 

the  addition  of  2  to  4  per  cent  of  acetic  acid,  and  care  must  be  taken  to 
avoid  unevenness  as  tlie  basic  color  is  absorbed  very  rapidly.*  The  sul- 
phur colors  may  also  be  topped  with  the  ordinary  substantive  dyes  in  a 
fresh  bath,  f  or  certain  of  the  latter  may  be  used  together  with  the  sulphur 
dyes  in  the  same  bath.  |  The  sulphur  dyes  may  also  be  topped  with  Indigo 
for  the  purpose  of  obtaining  very  fast  heavy  shades  of  the  latter  with  only 
a  small  amount  of  Indigo  being  used.  The  Sulphur  Blues  and  Blacks  are 
chiefly  used  for  this  purpose. §  The  Sulphur  Blacks  may  also  be  topped 
with  one-bath  Aniline  Black,  especially  where  a  weighting  of  the  cotton 
is  desired.  The  Aniline  Black  is  applied  in  the  following  bath:  4  per  cent 
of  aniline  salt,  6  per  cent  of  hydrochloric  acid  (30°  Tw.),  3  per  cent  of  sul- 
phuric acid  (168°  Tw.),  3  per  cent  of  bluestone,  and  4  per  cent  of  chrome. 
The  cotton  (previously  dyed  with  the  sulphur  color)  is  worked  in  the  cold 
bath  for  one  hour.  The  bath  is  then  slowly  heated  to  140°  F.,  and  the 
goods  are  finally  well  washed  and  soaped.  The  advantage  of  this  process 
of  dyeing,  however,  over  the  plain  Sulphur  Black  is  to  be  questioned.  The 
natural  dyewoods,  as  well  as  the  Alizarine  colors,  may  also  be  used  for 
topping  the  sulphur  colors,  but  such  processes  would  have  very  little 
application.^ 

6.  Fastness  of  Sulphur  Colors. — In  general  fastness  the  sulphur  dyes 
far  surpass  most  other  cotton  colors.  They  have  great  fastness  to  washing, 
fulling,  acids,  alkalies,  and  water,  and  their  fastness  to  light  is  in  general 

*  If  only  a  very  small  amount  of  the  basic  dye  is  used  for  shading  purposes,  it  may  be 
dyed  in  a  cold  soap  bath;  but  in  this  case  it  is  necessary  to  avoid  carefully  the  use  of 
hard  water. 

t  The  sulphur  dyes  may  also  be  used  as  ground  colors  for  Paranitraniline  Red,  thus 
producing  claret  reds,  grenades,  and  dark  brown  shades. 

I  In  this  case,  however,  the  dyestuff  solutions  must  be  prepared  separately  and 
added  to  the  bath.  Naturally,  only  those  substantive  dyes  may  be  used  that  are  not 
affected  by  the  sodium  sulphide  present  in  the  bath. 

§  The  sulphur  dyes  (and  more  especially  Sulphur  Blue)  apparently  act  as  a  mordant 
towards  Indigo.  Cotton  wares  dyed  with  Sulphur  Blue  and  then  dyed  in  the  indigo 
vat  take  up  considerably  more  Indigo  than  undyed  cotton.  In  this  way  the  sulphur 
dye  forms  a  very  good  bottom  color  for  the  Indigo;  and  in  fact,  this  process  has  found 
considerable  use  in  practice,  as  by  its  means  a  heavy  shade  of  indigo  blue  may  be 
obtained  with  a  minimum  quantity  of  Indigo,  and  the  color  is  just  as  fast  as  with  Indigo 
alone. 

II  During  the  war  navy  blue  on  cotton  uniform  cloth  and  overalls  was  dyed  by  first 
dyeing  the  material  a  medium  shade  with  Sulphur  Black  and  then  topping  with  Methy- 
lene Blue  and  Methyl  Violet.  In  topping  the  suli)hur  colors  with  basic  dyes  the  sulphur 
dyed  cotton  must  be  thoroughly  washed  in  order  to  remove  all  alkali  and  sodium  sul- 
phide as  completely  as  possible.  The  basic  dye  is  then  applied  in  a  cold  bath  with  the 
addition  of  5  per  cent  of  acetic  acid  or  alum  to  prevent  the  color  from  going  on  too  quickly, 
as  the  sulphur  dye  possesses  a  strong  affinity  for  the  basic  dye.  It  is  necessary  that  the 
topping  bath  should  be  kept  acid  throughout,  for  if  the  cotton  has  not  been  thoroughly 
washed  the  sodium  sulphide  may  act  on  the  basic  dye. 


390 


SULPHUR  T>Y1£S 


good.*     They  are  not  fast,  however,  to  bleachmg  with  chloride  of  Umc; 
though  certain  of  them  withstand  a  sHght  treatment  with  this  reagent. 

As  a  rule,  the  sulphur  dyes  are  taken  up  b}-  cotton  verj'  evenly;  though 
in  cases  where  an  after-treatment  is  necessary  to  develop  the  color,  care 
should  be  taken  to  have  the  goods  squeezed  uniformlj^,  otherwise  they 
are  liable  to  finish  up  unevenly.  In  fastness  to  rubbing  or  crocking  the  '~ 
sulphur  dyes  are  ver>'  satisfactory,  provided  they  have  been  well  washed 
after  dyeing,  so  that  all  unfixed  dyestuff  and  liquor  is  completely  removed. 

The  sulphur  dyes  are  eminently  suited  for  cross-dye  colors,  where  dyed 
cotton  warps  are  woven  with  white  wool  filling,  and  the  latter  is  subse- 
quently dyed  in  an  acid  bath.     They  are  also  suitable  for  colored  weaving 


Fig   199. — Machine  for  Dyeing  Warjjs  with  Sulphur  Colors. 

yams  in  goods  which  must  stand  considerable  washing.  For  the  dyeing 
of  hosier}'  yarns  they  are  also  ver^-  useful;  the  Sulphur  Blacks,  as  a  rule, 
gix'ing  a  color  on  hosiery  as  satisfactory  in  every  respect  as  Aniline  Black, 
there  being  less  liability  of  tendering  the  cotton  and  the  goods  are  more 
comfortable  to  the  feet.  Furthermore  the  process  of  dj^eing  Sulphur  Black 
OQ  hosierj'  is  much  shorter  and  simpler  than  when  Aniline  Black  is  used, 
and  there  is  more  certainty  in  the  production  of  uniform  results.  The 
cost  of  dyeing  hosiery  with  Sulphur  Black  is  somewhat  les.s  than  with 
Aniline  Black. 

The  Sulphur  Browns  of  a  tan  shade  are  also  very  largely  used  in  the 
dyeing  of  cotton  hosiery  for  the  production  of  the  well-known  tan  colors. 
Much  faster  and  more  satisfactory  shades  on  hosier}^  can  be  obtained  in 
this  manner  than  with  the  substantive  dyes,  or  in  fact,  with  any  other  colors. 


*The  fastness  to  lig;ht  of  some  of  the  sulphur  dyes,  however,  is  onlj'  moderate. 
Therefore  care  should  be  used  in  the  proper  selection  of  these  dyestuffs. 


ACTION   ON   MERCERIZED   COTTON 


391 


For  the  purpose  of  brightening  the  colors  thus  produced  with  the  sulphur 
dyes  they  may  be  suitably  topped  with  such  basic  dyes  as  Safranine,  Flavo- 
phosphine,  Brilliant  Green,  and  Methylene  Blue.  The  topped  colors 
require  but  a  very  small  amount  of  the  basic  dye,  and  the  general  fastness 
is  not  changed.  The  sulphur  dyed  tans  are  much  more  satisfactory  for 
hosiery  than  those  obtained  with  Cutch,  as  the  color  is  not  only  faster,  but 
the  goods  are  left  in  a  soft  condition  and  not  made  harsh  and  stiff  as  with 
Cutch. 


Fig.  200.— Cop  and  Cheese  Dyeing  Machines  for  Sulphur  Colors.     (Haubold.) 

Sulphur  Black  and  the  other  sulphur  dyestuffs  show  a  greater  affinity*: 
towards  mercerized  cotton  than  towards  the  unmercerized  fiber.  There-- 
fore  in  the  dyeing  of  mercerized  cotton,  smaller  amounts  of  dyestuff  must 
be  used  than  when  dyeing  ordinary  cotton.  Also  the  dyebath  should 
be  charged  with  much  less  salt,  and  it  is  also  permissible  to  employ  more 
dilute  baths.  Mercerized  cotton  should  always  be  wetted-out  before 
going  into  the  dyebath.  Artificial  silk  also  exhibits  a  strong  affinity 
towards  the  sulphur  dyes,  the  collodion  or  Chardonnet  silk  being  espe- 
cially reactive  in  this  respect.     As  artificial  silk  is  quite  sensitive  to  hot 


^ycij^CH 


392  SULPHUR  DYES 

solutions  of  caustic  alkalies  (sodium  hydrate  or  sodium  sulphide)  in  dyeing 
this  fiber  the  alkalinity  of  the  bath  should  be  as  little  as  possible,  and  the 
temperature  should  not  run  over  140°  F.  It  is  also  well  to^xW  Monopol 
Oil  to  the  bath.  ,.    ^  /  ^'7  /  ^,7 

Sulphur  Brown  (in  combination  with  Sulphur  BTac"k  and  Sulphur  Yellow 
as  required)  is  very  largely  emplojTd  for  tlic  production  of  brown  khaki 
and  olive-drab  shades  on  cotton  uniform  cloth.  Their  high  degree  of 
fastness  to  washing  and  light  renders  them  eminently  adapted  to  this  pur- 
pose. Heavy  cloth,  such  as  canvas,  tarpaulin,  etc.,  is  generallj^  dyed  with 
the  mineral  pigment  iron  buff  combined  with  chrome  green,  but  for  uni- 
form cloth  the  mineral  dyes  are  unsuitable  on  account  of  the  harshness  and 
stiffness  they  impart  to  the  fabric.  During  the  late  w^ar  the  sulphur  dyes 
were  used  on  an  enormous  scale  for  the  dyeing  of  government  cotton 
uniform  cloth,  and  the  results  obtained  were  very  good.  Of  course  since 
there  are  a  large  number  and  variety  of  Sulphur  Browns  made  from  a  wide 
variety  of  raw  materials  and  by  different  methods,  it  is  natural  to  find  some 
that  are  not  as  fast  as  others;  but  by  proper  selection  it  is  possible  to  obtain 
dyes  of  very  satisfactory  fastness.  As  the  colors  obtained  with  sulphur 
dyes  are  not  fast  to  chlorine  bleaching,  there  have  been  many  instances 
where  khaki  uniform  cloth  has  suffered  on  being  laundered  where  hypo- 
chlorite bleach  liquors  have  been  used  in  the  laundrj^  methods. 

Since  the  war  sulphur  dyes  have  also  come  into  considerable  vogue  for 
use  in  dyeing  denims  for  workmen's  overalls.  Formerlj'  this  class  of  goods 
was  dyed  almost  exclusively  with  Indigo,  in  fact  accounted  for  the  principal 
consumption  of  Indigo  in  this  country.  Sulphur  Browns  and  Sulphur  Blues 
are  now  extensively  used  for  this  cloth,  and  the  results  have  proved  so 
Satisfactory  that  no  doubt  they  will  permanently  replace  Indigo  to  a  very 
considerable  extent  in  the  future.  The  color  obtained  with  Indigo,  per- 
haps is  somewhat  brighter  and  clearer  in  tone  than  most  of  the  Sulphur 
Blues,  but  some  of  the  sulphur  colors  even  in  this  respect  are  practically 
the  equal  of  Indigo.  It  is  also  said  that  while  Indigo  gradually  loses  its 
intensity  of  color  on  long  exposure  to  light  and  by  repeated  washings,  it 
always  preserves  its  purity  of  tone,  whereas  the  Sulphur  Blues,  though  at 
times  even  superior  to  Indigo  in  retaining  the  depth  of  shade,  nevertheless 
soon  lose  their  purity  of  tone  and  become  tarnished  in  color.  While  this 
maj^  be  true  to  a  certain  extent,  it  has  little  effect  on  the  practical  use  of 
the  color.  The  use  of  sulphur  brown  and  khaki  shades  on  overall  material 
had  its  inspiration,  of  course,  in  the  extensive  use  of  khaki  during  the  war. 
These  shades  are  even  more  serviceable  in  practical  use  than  the  blue 
colors,  both  when  employed  in  solid  colors  and  when  used  as  stripes. 

Owing  to  the  great  interest  aroused  in  the  manufacture  of  sulphur  dyes 
in  this  country  and  their  extensive  use  by  reason  of  the  war,  the  possibilities 
of  their  application  to  various  forms  of  cotton  materials  for  the  production 


APPARATUS   FOR   DYEING 


393 


of  fast  colors  has  been  more  and  more  recognized  by  dyers  and  the  trade 
in  general.  As  a  consequence,  these  dyes  are  now  perhaps  far  more  used 
in  this  country  than  they  were  before  the  war,  and  wherever  it  is  possible  to 
produce  the  required  shades  they  have  largely  replaced  many  of  the  formerly 
used  substantive  colors,  as  they  are  much  faster  to  washing,  and  also  many 
of  them  are  less  expensive.  The  blue  sulphur  dyes,  however,  are  as  yet  of  a 
high  price  owing  to  the  methods  and  raw  materials  employed  in  their  man- 
ufacture; and  on  this  account  they  cannot  as  yet  be  employed  in  compe- 
tition with  Indigo  on  a  price  basis.  It  also  limits  their  use  considerably  in 
many  forms  of  cotton  dyeing,  where  such  dyes  as  Direct  Blue  2B  are  still 
employed. 

7.  Apparatus  Used  in  Dyeing  Sulphur  Colors. — As  a  rule  it  is  recom- 
mended when  dyeing  with  the  sulphur  colors  that  the  best  results  are  to  be 


Fig.  201.— Dye  Winch  for  Cloth. 


obtained  when  the  goods  are  kept  entirely  submerged  beneath  the  dye- 
liquor  during  the  dyeing  process,  in  order  to  avoid  the  oxidation  of  the 
coloring  matter  on  the  fiber  by  exposure  to  the  air,  as  otherwise  precipita- 
tion of  unfixed  dyestuff  is  liable  to  take  place  and  give  rise  to  colors  that 
will  crock  and  bleed  off  in  washing. 

In  the  case  of  yarn  dyeing  the  skeins  may  be  kept  beneath  the  liquor 
in  ordinary  open  vat  dyeing  by  the  use  of  bent  iron  sticks  (see  Fig.  193) . 
This  system  was  largely  used  a  few  years  ago,  but  at  the  present  time  with 
the  use  of  more  highly  purified  dyes,  it  is  not  considered  so  important,  and 
the  dyeing  is  more  generally  carried  out  in  the  ordinary  manner  with  the 
use  of  straight  sticks.  Skein  yarn  may  also  be  dyed  on  a  revolving  spider 
type  of  machine,  constructed  of  iron  throughout  and  so  arranged  that  tha 
goods  are  kept  beneath  the  liquor. 


394 


SULPHUR  DYES 


In  the  dyeing  of  warps  two  general  types  of  machines  may  be  employed: 
first,  a  continuous  dyeing  machine  in  which  the  warps  run  through  from 


Fig.  202. — Small  Jigger  for  Dyeing  Samples  with  Sulphur  Dyes. 

end  to  end  in  rope  form;    and,  second,  beam  dyeing  machines,  in  which 
the  warp  is  wound  on  a  perforated  beam  and  dyed  by  circulating  the  liquor 


Fig.  203.— Submerged  Jigger  and  Washer  for  Sulphur  Dyes. 

through  the  goods.     The  continuous-warp  dyeing  machines  for  sulphur 
colors  are  usually  somewhat  differently  constructed  from  those  machines 


APPARATUS   FOR   DYEING 


395 


used  for  the  dyeing  of  the  ordinary  substantive  colors.  They  are  usually 
arranged  in  the  form  of  several  dye-tubs  separated  by  squeeze  rollers,  and 
the  warps  are  run  through  singly  without  being  doubled;    each  tub  is 


Fig.  204. — Jigger  for  Sulphur  Dyes. 


A  B 

Fig.  205.— Double  Jigger  for  Sulphur  Colors. 

provided  with  guide  rollers,  in  some  cases  so  arranged  as  to  keep  the  goods 
beneath  the  liquor,  while  in  other  cases  this  feature  is  not  insisted  upon. 
Usually  from  six  to  eight  warps,  separated  from  each  other  by  pot-eyes, 


396 


SULPHUR  DYES 


are  run  through  the  machine  simultaneously.     In  the  Fries  machine  the 
warps  arc  first  padded  with  the  dye  liquor,  then  run  through  a  steammg 


Fig.  206.— Padding  Jigger  for  Sulphur  Dyes.     (Mather  &  Piatt.) 

chest  to  fix  the  dyeing,  then  through  a  washer,  and  finally  over  drying  cans, 
thus  making  a  continuous  operation  of  the  entire  process  (see  Fig.  149). 


Fig.  207. — Double  Jigger  Rigged  for  Sulphur  Blue  Using  Second  Machine  for  Developing 

and  Washing. 

In  dyeing  warps  on  the  beam  the  perforated  l)eam  is  placed  in  a  tank  pro- 
vided with  suita])le  fittings  and  a  pump  so  that  the  dye  liquor  may  be 
forced  by  the  pump  from  the  perforated  beam  outward  through  the  warp. 


APPARATUS   FOR   DYEING 


397 


and  then  reversing  the  valve  the  Uqiior  may  be  pumped  in  the  opposite 
direction  (see  Fig.  197). 

For  the  dyeing  of  piece- 
goods  there  are  four  types 
of  apparatus;  first,  the 
ordinary  dye-tub  with 
winch  (see  Fig.  20,) ;  this 
form,  however,  is  very 
seldom  used  for  sulphur 
colors;  second,  the  jigger, 
which  is  very  similar  in 
construction  to  the  ordi- 
nary jigger  used  for  dyeing 
other  colors;  except  for 
sulphur  colors  the  tank 
and  parts  as  well  as  the 
rollers  are  usually  made  of 
iron,  and  frequently  the 
mechanism  is  so  arranged 
that  the  cloth  is  kept 
entirely  underneath  the 
liquor  (see  Figs.  202  and 
203).  Also  a  set  of  two 
jiggers  is  frequently  em- 
ployed, the  first  being 
used  for  the  dyeing  and  the 
second  for  the  rinsing  (see 
Figs.  204  and  205).  Third, 
we  have  the  continuous 
open-width  dyeing  ma- 
chine, consisting  of  a  series 
of  several  tanks  provided 
with  suitable  guide  rollers 
and  nips  (squeeze  rollers) ; 
the  construction  is  usually 
of  iron  throughout  and  the 
rolls  are  so  arranged  as  to 
keep  the  cloth  beneath  the 
liqucr.  Fourth,  the  dye- 
ing with  sulphur  colors 
is  frequently  carried  out 
on  a  padding  machine  re- 
sembling a  Foulard  (sec  Fig.  206).     This  is  used  for  rapid  work  where  a 


398 


SULPHUR  DYES 


surface  dyeing  only  is  permissible,  and  onl}-  for  comparatively  light 
shades.  By  steaming  the  goods  afterwards  better  penetration  and 
fixation  of  the  dyestuff  is  procured. 

Cotton  raw  stock  is  largely  dyed  with  the  sulphur  colors  for  solid  shades 
for  the  purpose  of  making  mixes  with  white  or  other  colors.  On  a  small 
scale  it  is  customary  to  dye  the  stock  in  an  open  tul)  or  vat  and  circulate 
the  material  by  poling  by  hand,  such  as  is  ordinarily  practiced  in  the  dye- 
ing of  other  classes  of  cotton  colors.  On  a  large  scale,  however,  it  is  gen- 
erally the  practice  to  employ  an  apparatus  in  which  the  dye  liquor  is 
circulated  through  the  closely  packed  cotton,  as  in  the  type  generally 
known  as  the  Psarski  dyeing  machine  (see  Fig.  128).  This  machine  is 
particularly  adapted  to  the  dyeing  of  sulphur  colors,  as  there  is  but  little 


Fig.  209. — Continuous  Dyeing  Machine. 


exposure  of  the  liquor  to  the  air,  and  furthermore  a  rather  concentrated 
dye  liquor  may  be  used.  After  dyeing  the  material  may  be  readily  washed 
in  the  same  machine. 

Cotton  yarns  in  package  form,  such  as  cops,  tubes,  and  cheeses,  may 
also  be  dyed  very  satisfactorily  with  the  sulphur  dyes  in  special  forms  of 
apparatus,  such  as  already  described  under  the  methods  employed  for 
the  dyeing  of  substantive  colors. 

It  has  also  been  suggested  to  employ  foam  dyeing  with  the  sulphur 
colors.  In  this  process  an  apparatus  is  used  as  shown  in  Figs.  212  and  213. 
A  small  quantity  of  concentrated  dye  liquor  consisting  of  the  solutions  of 
dyestuff  and  sodium  sulphitle  with  additions  of  T\u-key-red  oil  and  soap  is 
used  in  the  bottom  of  the  tank,  so  that  the  level  of  the  liquor  does  not 
quite  reach  up  to  the  bottom  of  the  cage  containing  the  cotton  material 


APPARATUS   FOR   DYiUiNG 


399 


(yarns,  cops,  cheeses,  etc.).  The  Hquor,  on  being  boiled  vigorously,  pro- 
duces a  great  deal  of  foam,  which  comes  in  contact  with  the  goods  and 
causes  the  dyestuff  to  penetrate  even  such  dense  packages  as  cops  and 


Fig.  210. — Dyeing  Sulphur  Colors  on  Foulard. 


tubes.  Usually  direct  steam  is  also  used  to  produce  a  more  copious  foam- 
ing. The  property  of  the  dyestuff  foam  of  penetrating  the  goods  so  as  to 
yield  even  dyeings  entirely  through  the  mass  of  the  material  is  rather 


DYE-BATH 

Fig.  211. — Dyebath  and  Rinse-Bo.x  for  Sulphur  Dyes. 


remarkable,  and  is  probably  due  to  the  surface  tension  of  the  foam  bubbles. 
The  same  is  also  true  when  dyeing  in  ordinary  cop  dyeing  machines,  where 


400 


SULPHUR  DYES 


the  liquor  is  to  bo  sucked  back  aiul  forth  through  the  cotton;    if  some 
Turkey-red  oil  and  a  little  soap  are  added  to  the  bath  it  will  tend  to  foam 


Fig.  212. — Dye  Box  for  Continuous  Dyeing  Sulphur  Colors. 


..^-r^ 


Fig.  213. — Apparatus  for  Foam  Dyeing. 


considerably  on  vigorous  boiling,  and  the  penetration  of  the  color  will  be 
much  more  rapid  and  complete  than  would  otherwise  be  the  case. 


PRINCIPAL  SULPHUR   DYES 


401 


8.  List  of  Principal  Sulphur  Dyes 
(a)  Red 


Auronal  Corinth 
Immedial  Bordeaux 
Katigen  Bordeaux 


Auronal  Orange 
EcUpse  Orange 
EcHpse  Phosphine. 
Immedial  Orange 


Auronal  Yellow 
Cross  Dye  Yellow 
Eclipse  Yellow 
Immedial  Yellow 
Katigen  Yellow 
Kryogene  Yellow 
Pyrogene  Yellow 


Auronal  Green 
Cross  Dye  Green 
Eclipse  Fast  Green 
Eclipse  Fast  Olive 
Eclipse  Green 
Eclipse  Olive 
Immedial  Brilliant  Green 
Immedial  Dark  Green 
Immedial  Deep  Green 
Immedial  Green 
Immedial  Olive 
Immedial  Yellow  Olive 
Katigen  Brilliant  Green 
Katigen  Chrome  Blue  5G 
Katigen  Dark  Green 


Auronal  Blue 
Cross  Dye  Blue 
Eclipse  Blue 
Eclipse  Fast  Dark  Blue 
Eclipse  Violet 
Immedial  Blue 
Immedial  Dark  Blue 
Immedial  Direct  Blue 
Immedial  Green  Blue 
Immedial  Indogene 


Sulphur  Corinth 
Sulphurol  Bordeaux 
Thiogene  Dark  Red 

(b)  Orange 

Pyrogene  Orange 
Sulphurol  Orange 
Thiogene  Orange 
Thion  Orange 

(c)  Yellow 

Pyrol  Yellow 
Sulphogene  Yellow 
Sulphur  Yellow 
Sulphurol  Yellow 
Thiogene  Golden  Yellow 
Thiogene  Yellow 

(d)  Green 

Katigen  Green 
Katigen  Olive 
Kryogene  Olive 
Nigrosulphine 
Pyrogene  Blue  Green 
Pyrogene  Dark  Green 
Pyrogene  Green 
Pyrogene  Olive 
Pyrol  Green 
Sulphogene  Green 
Sulphur  Olive 
Sulphurol  Dark  Green 
Sulphurol  Green 
Thiogene  Green 
Thion  Green 

(e)  Blue 

Immedial  Indone 
Immedial  Indone  Violet 
Immedial  New  Blue 
Immedial  Prune 
Immedial  Pure  Blue 
Immedial  Sky  Blue 
Immedial  Violet 
Katigen  Azurine 
Katigen  Blue  B 
Katigen  Chrome  Blue 


Thiogene  Purple 
Thionone  Corinth 


Thionol  Orange 
Thiophor  Orange 
Thioxine  Orange 


Thion  Yellow 
Thional  Yellow 
Thionol  Yellow 
Thionone  Yellow 
Thiophor  Yellow 
Thioxine  Yellow 


Thional  Brilliant  Green 
Thional  Dark  Green 
Thional  Green 
Thionol  Brilliant  Green 
Thionol  Dark  Green 
Thionol  Green 
Thionol  Olive 
Thionone  Green 
Thiophor  Dark  Green 
Thiophor  Deep  Green 
Thiophor  Green 
Thiophor  Olive 
Thiophor  Yellow  Olive 
Thioxine  Olive 


Katigen  Dark  Blue 
Katigen  Direct  Blue 
Katigen  Indigo 
Katigen  Navy  Blue 
Katigen  Violet 
Kryogene  Blue 
Kryogene  Direct  Blue 
Kryogene  Violet 
Melanogen  Blue 
Pyrogene  Blue 


402 


SULPHUR  DYES 


Pyrogene  Cyanine 
Pyrogene  Direct  Blue 
P^TOgene  Indigo  Blue 
Pyrol  Blue 
Pyrol  Direct  Blue 
Pyrol  Navy  Blue 
Sulphogene  Blue 
Sulphur  Blue 
Sulphur  Indigo 
Sulphurol  Direct  Blue 
Sulphurol  Indigo 
Thiogene  Blue 
Thiogene  Cyanine 


Auronal  Black  Brown 
Auronal  Khaki 
Cachou  de  Laval 
Cachou  R 
Cross  Dye  Brown 
Cross  Dye  Drab 
Eclipse  Bronze 
Eclipse  Brown 
Eclipse  Red  Brown 
Immedial  Bronze 
Immedial  Brown 
Immedial  Cutch 
Immedial  Dark  Brown 
Immedial  Maroon 
Immedial  Red  Brown 
Immedial  Yellow  Brown 
Katigen  Black  Brown 
Katigen  Bronze 
Katigen  Brown 
Katigen  Chrome  Brown 
Katigen  Cutch 
Katigen  Khaki 
Katigen  Red  Brown 


Thiogene  Dark  Blue 
Thiogene  Deep  Blue 
Thiogene  Direct  Blue 
Thiogene  Heliotrope 
Thiogene  New  Blue 
Thiogene  Violet 
Thion  Blue 
Thion  Deep  Violet 
Thion  Direct  Blue 
Thion  Navy  Blue 
Thion  Violet 
Thional  Blue 
Thional  Indigo 

(f)  Brown 

Katigen  Yellow  Brown 
Kryogene  Brown 
Krj'ogene  Red  Brown 
Pyrogene  Brown 
Pyrogene  Catechu 
Pyrol  Bronze 
Pyrol  Brown 
Pyrol  Dark  Brown 
Pyrol  Red  Brown 
Sulphanil  Brown 
Sulphogene  Brown 
Sulphur  Brown 
Sulphur  Catechu 
Sulphurol  Brown 
Sulphurol  Dark  Brown 
Thiocatechine 
Thiogene  Bronze 
Thiogene  Brown 
Thiogene  Cutch 
Thiogene  Dark  Red 
Thiogene  Khaki 
Thiogene  Olive 
Thiogene  Yellow  Brown 


Thionol  Blue 
Thionol  Brilliant  Blue 
Thionol  Dark  Blue 
Thionol  Dark  Purple 
Thionol  Direct  Blue 
Thionone  Brilliant  Blue 
Thionone  Indigo 
Thionone  Navy  Blue 
Thiophor  Blue 
Thiophor  Cyanine 
Thiophor  Dark  Blue 
Thiophor  Indigo 
Thiophor  Violet 


Thion  Brown 
Thion  Cutch 
Thion  Violet  Brown 
Thional  Bronze 
Thional  Brown 
Thional  Dark  Brown 
Thionol  Brilliant  Corinth 
Thionol  Brown 
Thionol  Corinth 
Thionol  Khaki 
Thionone  Brown 
Thionone  Dark  Brown 
Thionone  Drab 
Thionone  Khaki 
Thiophor  Black  Brown 
Thiophor  Bronze 
Thiophor  Brown 
Thiophor  Dark  Brown 
Thiophor  Red  Brown 
Thiophor  Violet  Brown 
Thiophor  Yellow  Brown 
Thioxine  Brown 
Vulcan  Brown 


Anthraquinone    Black 
Atlantic  Black  B,  G,  R 
Auronal  Black 
Autogenc  Black 
Cross  Dye  Black 
Eclipse  Black 
Immedial  Black 
Immedial  Brilliant  Black 
Immedial  Brilliant  Carbone 
Immedial  Carbone 
Indo  Carbone 


(g)  Black 

Katigen  Black 
Katigen  Blue  Black 
Katigen  Deep  Black 
Kryogene  Black 
Melanogen 
Mercaptol  Black 
Osfathion  Black 
Pyrogene  Black 
Pyrogene  Deep  Black 
Pyrogene  Gray 
Pyrol  Black 


Pyrol  Blue  Black 
Pyrol  Brilliant  Black 
Sulplianil  Black 
Sulphenol  Black 
Sulphogene  Black 
Sulphur  Black 
Sulphur  Blue  Black 
Sulphurol  Black 
Thiocarbone 
Thiogene  Black 
Thiogene  Black  Liquid 


EXPERIMENTAL   STUDIES  403 

Thiogene  Coal  Black  Thionone  Black  Thiophor  Brilliant  Carbon 

Thiogene  Diamond  Black  Thionone  Black  Paste  Thiophor  Carbon 

Thion  Black  Thionone  Deep  Black  Thiophor  Deep  Black 

Thional  Black  Thionone  Printing  Black        Thiophor  Field  Gray 

Thionol  Black  Thiophenol  Black  Thioxine  Black 

Thionol  Brilliant  Black  Thiophor  Black  Vidal  Black 
Thionol  Gray 

9.  Experimental.  Exp.  142.  General  Method  of  Applying  Sulphur  Dyes. — 
Prepare  a  bath  containing  5  per  cent  of  Sulphur  Brown,  5  per  cent  of  sodium  sulphide,  5 
per  cent  of  soda  ash,  and  25  per  cent  of  common  salt.  D3^e  a  skein  of  cotton  yani  in  this 
bath,  entering  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for 
one-half  hour;  wash  and  dry.  It  will  be  noticed  that  the  dj^ebath  does  not  exhaust 
verj'  well,  so  dye  a  second  skein  of  cotton  yarn  in  the  same  bath  without  adding  any 
further  dyestuff  or  chemicals,  only  diluting  the  bath  to  its  original  volume  with  water. 
Also  dye  a  third  skein  in  the  same  manner.  Compare  the  colors  on  the  three  skeins, 
the  gradation  of  which  will  show  the  comparative  exhaustion  of  the  bath. 

Exp.  143.  After-treatment  of  Sulphur  Dyes  with  Chrome. — An  after-treatment  with 
chrome  is  sometimes  given  in  order  to  obtain  a  faster  color.  Dye  a  skein  of  cotton  yarn 
with  5  per  cent  of  Sulphur  Brown  in  the  same  manner  as  above  described;  squeeze, 
rinse,  and  treat  in  a  fresh  bath  containing  2  per  cent  of  chrome  and  3  per  cent  of  acetic 
acid;  boil  for  fifteen  minutes;  wash  well  and  dry.*  Compare  the  color  of  this  skein 
with  the  corresponding  one  in  the  previous  exjieriment  and  note  the  effect  of  the  after- 
treatment  on  the  tone  of  the  color.  Also  test  the  fastness  of  these  two  dyeings  to  wash- 
ing and  cross-dyeing. 

Exp.  144.  Obtaining  Black  with  Sulphur  Dyes. — Dye  a  skein  of  cotton  yarn  in  a 
bath  containing  10  per  cent  of  Sulphur  Black  A  extra,  15  per  cent  of  sodium  sulphide, 

5  per  cent  of  soda  ash,  and  50  per  cent  of  common  salt;  enter  at  140°  F.,  gradually 
raise  to  the  boil,  and  dj-e  at  that  temperature  for  one-half  hour;  wash  well,  and  treat  in  a 
bath  containing  2  per  cent  of  olive  oil  emulsion;  then  rinse  and  dry.  Test  the  color  of 
this  skein  for  fastness  to  washing  and  cross-dyeing. 

Dilute  the  above  dyebath  to  its  original  volume  with  water,  and  without  further  addi- 
tion of  dyestuff  or  other  ingredient,  dye  a  second  skein  of  cotton  yarn.  This  will  give 
the  exhaust  test  of  the  bath  and  show  the  relative  amount  of  dyestuff  left  behind  in  the 
dye  liquor. 

Prepare  another  dyebath  as  first  given  above  with  10  per  cent  of  Sulphur  Black;  dj'e 
a  skein  of  cotton  yarn,  squeeze  well  so  that  the  liquor  runs  back  into  the  bath.     Now  add 

6  per  cent  of  dyestuff  dissolved  in  an  equal  quantity  (6  per  cent)  of  sodium  sulphide,  1 
per  cent  of  soda  ash  and  10  per  cent  of  common  salt.  Dye  a  second  skein  in  this  bath, 
and  compare  the  depth  of  color  with  the  first  skein.  IMake  up  the  bath  again  adding  4 
per  cent  of  dyestuff  dissolved  in  4  per  cent  of  sodium  sulphide,  but  make  no  further 
additions  of  soda  ash  or  salt.     Test  the  bath  to  see  if  the  dye  is  well  dissolved  by  putting 

*  Other  methods  of  after-treatment  which  have  been  recommended  are  as  follows: 
(1)  The  dj-eings  are  treated  in  a  fresh  bath  for  about  one-half  hour  at  the  ordinarj' 
temperature  with  3  to  5  per  cent  of  zinc  sulphate  and  3  to  5  per  cent  of  sodium  acetate. 
This  method  is  u.sed  with  certain  of  the  Sulphur  Browns,  and  causes  but  slight  change 
in  the  tone  of  color,  but  increases  the  fastness  to  washing.  (2)  Treat  the  dyed  material 
in  a  fresh  boiling  bath  for  about  one-half  hour  with  1  to  2  per  cent  of  chrome  and  1  to  2 
per  cent  of  bluestone  and  3  per  cent  of  acetic  acid.  This  treatment  is  used  on  many  of 
the  Sulphur  Browns,  and  while  making  the  tone  of  color  somewhat  duller  and  darker, 
in  many  cases  considerably  increases  the  fastness  to  washing  and  light. 


404  SULPHUR  DYES 

a  drop  on  filter  paper  when  it  should  not  show  any  insoluble  sediment.  Dj'e  a  third 
skein  in  this  bath  and  note  if  the  color  Ls  equal  to  that  of  the  first  dyeing.  In  all  cases 
dilute  the  dyebath  with  water  to  its  oripinal  volume.  After  the  last  dj-eing,  and  after 
proper  dilution  with  water  to  the  original  volume,  test  the  density  of  the  bath  with  a 
hydrometer  at  a  temperature  of  160°  F.     Also  take  the  density'  when  the  bath  is  cold. 

Exp.  145.  Use  of  Sulphur  Blue. — Dye  a  skein  of  cotton  yarn  in  a  bath  containing 
5  per  cent  of  Direct  Sulphur  Blue,  10  per  cent  of  sodium  sulphide,  5  per  cent  of  soda 
ash,  and  50  per  cent  of  common  salt.  Enter  at  140  to  100°  F.  and  graduallj'  raise  to  the 
boil,  and  dye  at  that  temperature  for  three-quarters  of  an  hour.  Then  squeeze,  allow 
the  skein  to  cool  and  rinse  well,  and  dr.*. 

Exp.  146.  Use  of  Sulphur  Blue  Requiring  Development. — Prepare  a  dyebath  as 
before  but  use  5  per  cent  of  Sulphur  Blue  L  Cor  one  of  similar  t}-pe)  and  one-half  per  cent 
of  caustic  soda  in  addition  to  the  sodium  sulphide,  soda  ash,  and  common  salt.  Dye  a 
skein  of  cotton  yarn  in  this  as  before:  squeeze  and  then  develop  the  dyeing  by  steaming.* 

Exp.  147.  Use  of  Sulphur  Yellow. — Dye  a  skein  of  cotton  yarn  in  a  bath  containing 
5  per  cent  of  Sulphur  Yellon',  7  per  cent  of  sodium  sulphide,  5  per  cent  of  soda  ash,  and 
50  per  cent  of  common  salt.  Enter  at  140  to  160°  F.  and  gradually  bring  to  the  boil. 
Dye  at  this  temperature  for  three-quarters  of  an  hour,  then  squeeze  and  wash  well. 

Exp.  148.  Topping  a  Sulphur  Dye  with  Basic  Dye. — Dye  a  skein  of  cotton  yam  as  in 
Exp.  145  with  5  per  cent  of  Direct  Sulphur  Blue,  squeeze  and  rinse,  and  then  top  by 
dj-eing  in  a  fresh  bath  at  140°  F.  with  jVp^'"  ^^^^  ^^  Methylene  Blue  and  2  per  cent  of 
acetic  acid.  Notice  the  change  in  shade  due  to  the  topping  and  also  test  the  fastness 
of  the  dyeing  to  washing. 

Exp.  149.  Dyeing  Khaki  with  Sulphur  Dyes. — Dye  a  skein  of  cotton  yarn  in  a  bath 
containing  5  per  cent  of  Sulphur  Khaki,  5  per  cent  of  .sodium  sulphide,  2  per  cent  of  soda 
ash,  and  50  per  cent  of  common  salt.  Enter  at  160°  F.  and  gradually  raise  to  the  bcil 
and  dye  at  that  temperature  for  three-quarters  of  an  hour.  Squeeze  and  rinse  and  wash 
off  in  a  weak  soap  bath  at  100°  F.,  and  drj\  Test  thLs  color  for  fastness  to  light  and 
washing. 

*  If  it  is  not  convenient  to  carry  out  the  development  process  by  steaming,  treat 
the  dyed  skein  in  a  dilute  bath  of  hydrogen  pero.xide,  using  10  cc.  of  hydrogen  pero.xidc 
(12-volume  strength)  to  300  cc.  of  water.  For  the  development  of  some  Sulphur  Blues 
(like  Sulphur  Indigo  and  its  type)  it  is  advantageous  to  emploj'  the  following  treatment: 
1  per  cent  of  chrome,  3  per  cent  of  bluestone,  and  5  per  cent  of  acetic  acid;  work  the 
dyed  cotton  in  this  bath  for  one-half  hour  at  the  boil;  rinse  well,  and  then  rinse  again 
in  a  bath  containing  2  per  cent  of  soda  ash  and  2  per  cent  of  soap  at  160°  F. 


CHAPTER  XVIII 
THE  VAT  DYES  f^Ji-  H;.  ^ 

1.  Classes  of  Vat  Dyes.^^^he  vat  dyes  are  so  called  because  they  are- 
applied  in  a  special  kind  of  a  dyebath  in  which  the  dye  is  reduced  to  a 
soluble  form  by  means  of  a  strong  reducing  agent,  such  as  hydrosulphite. 

The  vat  dyes  are  to  be  divided  into  several  groups,  depending  upon  their 
chemical  nature  and  origin,  as  follows: 

(a)  Indigo,  including  both  natural  and  synthetic. 
Qi)   Thio-indigo  dyes,  containing  sulphur. 

(c)  Indigo  derivatives,  such  as  the  brom-indigos;  usually  not  derived  directly  from 
indigo  itself,  but  built  up  synthetically. 

(d)  Anthraquinone  derivatives,  including  the  various  Indanthrene,  Cibanone,  Algol 
dyes,  some  HeUndone,  and  others. 

(e)  Carbazol  derivatives,  of  which  Hydron  Blue  is  the  chief  representative. 

In  a  broad  sense,  all  of  the  vat  dyes  at  present  known  appear  to  be 
members  of  three  distinct  chemical  groups: 

(a)  Indigoids  including  Indigo  and  its  various  derivatives  such  as  the  Thio-indigos, 
Helindone  and  Ciba  dyes,  and  some  of  the  red  Algol  dyes.  The  chemical  constitution 
of  this  class  is  similar  to  that  of  Indigo.  They  may  be  applied  in  a  neutral  or  slightly 
alkaline  bath,  and  hence  may  be  used  for  both  wool  and  cotton  dyeing.  Their  reduc- 
tion products  are  pale  yellow  or  almost  colorless  (similar  to  indigo),  which  exposure  to 
the  air  re-oxidizes  to  the  original  color.  As  distinguished  from  the  next  class  they  are 
sublimed  as  colored  vapors  from  the  fiber  when  heated. 

(6)  Anthroqiiinone  dyes,*  including  the  Indanthrene,  the  Cibanone,  and  most  of  the 
Algol  dyes.  They  are  complex  derivatives  of  anthraquinone  and  require  a  strongly 
alkahne  vat  in  dyeing,  consequently  they  are  only  useful  for  the  dyeing  of  cotton.  In 
common  with  all  the  dyes  of  the  anthracene  class  their  reduced  compounds  are  not 
colorless  but  have  about  the  same  color  as  the  original  dye.  When  the  dyed  fiber  is 
heated  these  dyes  do  not  sublime  or  form  colored  vapors  as  with  the  indigoids. 

(c)   Carbazol  Dyes,  or  Hydron  Blue. 

With  the  exception  of  Indigo  the  vat  dyes  are  all  of  comparatively 
recent  introduction.     The  dyes  themselves  are  highly  insoluble  in  water, 

*  Of  the  different  classes  of  vat  dyes  in  a  general  way  it  may  be  said  that  the  anthra- 
quinone dyes  are  the  fastest,  the  carbazol  dyes  are  next  and  the  indigoid  dyes  are  the 
least  fast.  On  the  other  hand,  however,  the  indigoid  dyes  are  easier  to  dye.  Indigo  is 
faster  on  wool  than  it  is  on  cotton. 

405 


406  THE  VAT  DYES 

but  readily  yield  products  on  reduction  which  are  soluble  in  alkaline  liquids. 
The  dycbath,  therefore,  consists  of  a  mixture  of  the  dyestuff,  a  strong 
reducing  agent  and  an  alkali;  and  such  a  mixture  is  termed  a  "  vat."* 

The  vat  dyes  at  present  include  quite  a  wide  range  of  colors;  IndigcT 
is  a  blue  dyestuff,  the  thio-indigo  dyes  and  their  derivatives  are  mostly 
reds   and   scarlets,  the  anthraquinone  dyes  include  blue,  yellow,  brown, 
green,  violet,  gray,  orange,  etc.     The  carbazol  dyes  are  blue.     The  vat' 
dyes  are  characterized  in  general  by  great  fastness  to  light,  washing,  acids,  • 
alkalies,  and  in  many  cases  to  bleaching  with  hj^pochlorites.f     This  makes 
them  very  valuable  products,  especially  for  cotton  goods,  and  they  have 
been  coming  more  and  more  into  use,  and  show  every  indication  of  ranking 

*  The  different  classes  of  vat  dyes  vary  considerably  in  their  ease  of  application; 
the  anthracene  dyes  are  the  most  difficult  to  apply,  while  the  indigoid  and  carbazol 
colors  are  much  easier  to  dye,  especially  with  regard  to  penetration  and  even  colors. 
The  halogenated  anthracene  dyes  are  much  better  in  this  respect  than  the  non-halo- 
genated  dyes.  The  hydron  series  is  the  only  one  which  includes  a  navy  blue  at  a  rea- 
sonable price,  the  other  classes  of  colors  have  always  been  very  high  in  price.  In  the 
dyeing  of  compound  shades  with  the  vat  dyes  there  is  frequently  considerable  difficulty 
experienced,  especially  in  obtaining  even  colors.  It  may  also  be  remarked  that  while  the 
self  shades  of  two  colors  may  be  fast,  when  dyed  in  mixture  the  compound  shade  may  not 
be  as  fast,  but  on  the  other  hand  the  opposite  may  also  be  true;  Anthraflavone,  for 
example,  is  not  very  fast  as  a  self  shade,  but  when  dyed  in  combination  with  Indanthrene 
Blue  the  compound  shade  is  very  fast.  It  must  also  be  remembered  that  some  of  the 
vat  dyes  are  applied  best  at  one  temjierature  and  some  at  another  and  in  dyeing  mixtures 
a  proper  balance  of  temperature  must  be  maintained,  as  the  correct  temperature  in  the 
dyeing  of  vat  dyes  is  of  the  utmost  importance  if  the  best  results  are  to  be  obtained. 
The  anthracene  vat  dyes  require  the  use  of  more  alkali  in  the  vat  than  the  dyes  of  the 
indigoid  or  hydron  series  (about  four  times  as  much),  but  on  the  other  hand  they  require 
much  less  hydrosulphite.  The  amount  of  caustic  soda  to  be  used,  strange  to  say,  is  to 
be  calculated  on  the  volume  of  the  liquor  employed  and  not  on  the  amount  of  dye- 
stuff  u.sed,  so  that  in  d^'eing  a  light  shade  just  as  much  caustic  soda  is  required  as  for  a 
heavy  shade.  In  using  a  mixture  of  vat  dyes  for  the  production  of  compound  shades  it 
is  always  best  to  first  reduce  each  dyestuff  separately  and  then  mix  them  in  the  dyebath. 

t  Though  the  vat  colors  in  general  are  fast  to  bleaching  with  hypochlorite  liquors 
(known  as  fast  to  chlorine),  they  do  not  as  a  rule  withstand  kier-boiling  with  caustic 
soda  (an  operation  which  usually  precedes  bleaching).  Their  fastness  in  this  respect 
has  been  found  to  be  improved  by  boiling  with  sodium  perborate.  It  has  also  been 
found  that  by  introducing  a  small  quantity  of  potassium  bromate  (5  oz.  per  gallon)  into 
the  kier  liquor,  the  bleeding  of  the  color  may  be  largely  prevented.  The  use  of  a  small 
amount  of  anthraquinone  is  also  employed  for  the  same  purpose. 

In  kier-boiling  cotton  pieces  containing  yarns  dyed  with  the  vat  colors  it  will  some- 
times be  found  that  the  goods  at  the  bottom  of  the  kier  will  be  stained  by  the  marking 
off  of  the  color.  This  is  supposed  to  be  due  to  the  fact  that  the  alkali  in  the  kier  liquor 
together  with  the  impurities  removed  from  the  cloth  form  a  sort  of  local  vat  which 
reduces  and  dissolves  the  color,  thus  allowing  it  to  run.  Certain  products,  such  as 
Ludigol  (meta-nitro-benzene-sulphonic  acid)  have  been  recommended  as  additions  to 
the  kier  to  prevent  the  staining  of  the  goods,  but  it  is  a  question  as  to  whether  they  suc- 
cessfully accomplish  this  purpose. 


GENERAL   CHARACTERISTICS 


407 


as  the  principal  cotton  dyes  of  the  future.  As  they  are  rather  difficult  to 
manufacture  and  require  complicated  processes  in  their  preparation,  the 
vat  dyes  are  quite  expensive,  and  on  this  account  are  used  chiefly  for  the 
dyeing  of  raw  cotton  or  yarns  to  be  used  for  colored  stripes  in  otherwise 
white  fabrics,  so  that  only  a  relatively  small  amount  of  dyed  yarn  is  used 
in  the  total  fabric. 

Though  the  vat  dyes  may  be  applied  to  all  fibers  they  are  more  suited  - 
to  the  dyeing  of  cotton,  as  most  of  them  require  a  rather  strongly  alkaline 
dyevat.*     The  material  to  be  dyed  is  simply  immersed    in  the  "  vat  "* 
or  dyebath  until  the  goods  are  thoroughly  impregnated  with  the  solution. 
The  material  is  then  squeezed  and  exposed  to  the  air,  which  causes  the^-^ 
oxidation  of  the  reduced  ''  leuco  "  compound  and  the  formation  of  the 
color.     The  temperature  of  the  vat  is  usually  lukewarm  for  the  purpose  of^ 


Fig.  214.— Indigo  Mill.     (Ball  Form.)  Fig.  215.— Indigo  Mill.     (Cone  Form.) 


facilitating  the  impregnation  of  the  fiber  with  the  solution.  In  some  cases 
the  dipping  and  oxidation  have  to  be  repeated  several  times  in  order  to 
build  up  a  heavy  color. 

The  vat  dyes  have  come  to  be  very  essential  dyes  for  cotton,  as  it 
is  only  by  the  use  of  these  dyes  that  laundry-fast  colors  in  cotton  wash- 
fabrics  can  be  obtained.  They  are  necessary  dj^es  for  the  production 
of  colors  in  shirtings,  blouse  material,  cotton  skirtings,  and  hosiery  and 
such  fabrics  or  garments  that  require  to  be  frequently  laundered.     No 

*  The  vat  dyes  in  some  cases  have  been  proposed  for  use  with  wool,  but  owing  to  the 
fact  that  the  vat  is  strongly  alkaline  with  caustic  soda  it  is  difficult  to  apply  properly  the 
color  to  wool.  Most  of  the  vat  dyes  show  no  affinity  for  wool  below  a  temperature  of 
160°  F.,  and  glue  or  sulphonated  oil  soap  must  be  used  in  the  bath  to  protect  the  fiber 
from  the  action  of  the  alkali;  furthermore  in  order  to  obtain  fast  colors  it  is  necessary  to 
boil  the  dyed  goods  in  sulphuric  acid  to  destroy  the  hydrosulphite,  and  this  is  a  great 
disadvantage. 


408  THE  VAT  DYES 

other  class  of  colors  will  stand  the  bleaching  effect  of  the  hj'pochlorite 
liquors  used  in  whitening  cotton  goods  in  the  modern  laundry.  There  are 
but  few  other  dyes  with  this  property  (C'hloramine  Yellow).  It  was  on 
the  great  fastness  of  the  vat  dyes  that  the  reputation  of  the  excellent 
quality  and  fastness  of  the  German-made  dyes  became  so  strongly  fixed 
in  the  mind  of  the  public.  Many  of  the  vat  dyes  are  faster  than  Indigo, 
though  of  course  this  latter  dye  is  itself  to  be  considered  but  a  member 
of  the  general  class  of  vat  dyes. 

In  the  practical  use  of  the  vat  dyes  it  is  usually  the  custom  to  first  pre- 
pare a  stock  vat  or  solution  of  the  reduced  dyestutf ,  and  this  is  used  in  such 
quantities  as  may  be  necessary  for  the^te  plenishing  of  the  dyevat."  In 
the  preparation  of  this  stock  solution  the  following  is  a  tj'pical  method:* 

100  lbs.  of  dyestuff  (which  is  generally  in  the  form  of  a  paste  containing  20  per  cent  of 
dry  dye); 
20  gallons  of  water  at  160°  F.; 
2-6  gallons  of  caustic  soda  solution  of  76°  Tw.; 
10—40  lbs.  of  hydrosulphite  powder  (anhj'drous  sodium  hydro.sulphite). 

The  exact  amounts  of  hj'drosulphite  and  caustic  soda  will  depend  on  the 
particular  dyestuff  employed.  Very  frequently  some  Turkey-red  oil  (or 
similar  sulphonated  soluble  oil)  is  also  added. 

The  vat  is  best  made  up  in  a  wooden  barrel  or  tank  fitted  with  a  steam 
pipe  so  that  the  contents  may  be  maintained  at  a  temperature  of  160°  F. 
until  the  reduction  is  completed,  which  usually  requires  about  one  hour 
or  somewhat  less.  The  solution  may  then  be  made  up  to  40  or  50  gallons 
with  water  and  is  ready  for  use.  It  is  important  that  the  water  employed 
for  both  the  stock  solution  and  the  dyevat  should  first  have  the  dissolved 
air  corrected  by  the  addition  of  a  little  hydrosulphite  and  caustic  soda; 
100  gallons  of  water  will  usually  require  al)out  4  ozs.  of  caustic  soda  and  3 
ozs.  of  hydrosulphite.     As  far  as  possible  soft  water  should  be  used.     The 

*  Whittakcr  gives  the  following  typical  vats  for  the  three  classes  of  vat  dyes: 

(10  per  cent  Chloranthrene  Blue  BD  (10  per  cent  paste) 
30  per  cent  eaustic  soda  (76°  Tw.) 
2j  per  cent  hj^drosulphite  powder  cone. 

r  2  per  cent  Ciba  Blue  2R  powder 

Indigoid  Series \  7  per  cent  caustic  soda  (76°  Tw.) 

I  7  per  cent  hydrosulphite  powder  cone. 

r  6  per  cent  Hydron  Blue  G  paste 

Carbazol  Series \  6.6  per  cent  caustic  soda  (76°  Tw.) 

I.  6  per  cent  hydrosulphite  powder  cone. 

The  color  sliould  first  bo  stirred  up  to  a  smooth  paste  with  the  caustic  soda,  hot  water 
added,  and  then  the  hydrosulphite.  In  some  cases  it  may  be  found  necessary  to  heat  the 
liquor  even  to  the  boil  in  order  to  obtain  a  complete  solution. 


^ 


PREPARATION   OF   VAT  409 

purpose  of  the  correction  is  to  remove  the  dissolved  oxygen  and  the  hard- 
ness in  the  water  so  as  to  avoid  precipitation  of  the  dj^estuff. 

The  stock  solution  must  be  preserved  from  undue  exposure  to  the  air, 
otherwise  dyestuff  will  be  precipitated  and  cause  bad  shades.  This  same 
precaution  also  applies  to  the  dyevat.  The  latter  is  prepared  by  heating 
the  necessary  volume  of  water  to  about  100°  F.,  adding  the  necessary 
amount  of  caustic  soda  and  hydrosulphite  required  to  counteract  the  dis- 
solved oxygen,  and  then  adding  the  required  amount'  of  the  stock  dye 
solution..  The  vat  is  then  gently  stirred  and  allowed  to  rest  awhile  before 
use  for  dyeing.* 

When  yarn  is  dyed  it  should  first  be  well  boiled-out,  and  if  open  dye 
vats  are  used  the  yarn  should  be  entirely  submerged  beneath  the  liquor 
by  being  hung  on  bent  iron  rods  similar  to  those  recommended  for  use  in 
the  dyeing  of  sulphur  colors  (see  page  376).  ^TfT^yinng  yarn  it  is  also  . 
important  that  it  should  be  evenly  wrung  out  after  steeping  in  the  vat, 
and  more  even  results  are  always  obtained  if  several  dips  are  given. ■*'■  AffeF 
dyeing  and  wringing  the  yarn  is  then  exposed  to  the  air  for  about  thirty 
minutes  to  oxidize  completely  the  leuco-compound  to  the  dyestuff.  It 
is  then  boiled  in  a  bath  containing  about  2  lbs.  of  soap  per  100  gallons  of 
liquor. t  This  is  for  the  purpose  of  completely  developing  the  color  and 
removing  all  unfixed  dyestuff,  which  would  otherwise  dull  the  shade 
and  cause  crocking.'V    >  ■<-t.^  _  ^.   ,       ,  , 

On  account  of  the  difficulty  of  obtaining  even  shades  and  good  pene- 
tration of  color,  it  is  more  satisfactory  to  dye  vat  colors  in  the  loose  stock 
rather  than  on  yarn  or  piece-goods.  By  dyeing  yarn  in  the  form  of  warps, 
however,  very  good  results  can  be  obtained.     When  dj^eing  loose  stock  it  is 

*  In  the  preparation  of  the  dyebath  with  the  vat  dyes  it  is  sometimes  a  question  as 
to  when  the  proper  degree  of  reduction  is  obtained.     With  some  dyes  the  reduced  or 
leuco-compound  is  of  a  different  color  than  the  dye,  and  in  this  case  it  is  easy  to  deter- 
mine if  the  vat  is  completely  reduced;  for  instance,  Chloranthrcne  Yellow  gives  a  reduced 
vat  which  is  blue  in  color.    On  the  other  hand,  some  of  the  dyes  give  vats  of  the  same 
general  color  as  that  of  the  dye,  and  it  is  difficult  to  tell  just  when  the  color  is  reduced 
by  the  appearance  of  the  vat.     Chloranthrcne  Blue,  for  example,  gives  a  reduced  vat 
which  is  also  blue  in  color.     To  determine  if  reduction  in  such  a  case  is  complete  Whit- 
taker  recommends  drawing  out  some  of  the  vat  liquor  in  a  pipette  and  allowing  it  to  run 
slowly  clown  the  side  of  a  clean  test  tube  held  against  the  light;   if  the  d3^e  is  reduced  the 
liquor  will  show  clear,  but  if  it  is  not  completely  reduced  undissolved  particles  of  coir 
will  be  detected  in  the  liquid.     With  the  blues  of  the  indigoid  class,  like  Ciba  Blue,  t 
reduced  vats  are  bright  golden  yellow  in  color  and  consequently  there  is  little  diffic^ 
in  ascertaining  when  reduction  is  complete.  '  the 

t  Owing  to  the  large  amount  of  caustic  alkali  used  in  the  bath  with  the  vatmad- 
after  dyeing  the  cotton  the  goods  must  be  soured  in  a  weak  acid  bath  to  neutrp' 
alkali,  then  washed,  soaped  well  and  washed  again  before  drying.     The  soaping  ^^^^  ^^ 
necessary  operation,  as  it  both  develops  and  brightens  the  shade,  besides  sof^   ^  wool 
goods  and  ensuring  neutralization  of  all  acid. 


410  THE  VAT  DYES 

well  to  employ  some  form  of  dyeing;  machine  which  will  permit  of  the  dye 
liquor  being  circulated  through  the  material  with  a  minimum  exposure  to 
the  air.  Piece-goods  may  be  dyed  on  the  jigger,  preferably  on  that  form 
in  which  the  good?  are  kept  entirely  immersed,  otherwise  the  piece  will 
become  oxidized  at  the  edges  and  may  show  lists  or  streaks. 

The  vat  colors  in  general  are  well  adapted  for  machine  dyeing  of  cops, 
tubes,  warps,  etc.  In  Europe,  Indigo  (and  the  rest  of  the  vat  dyes)  is 
vePk'  largely  dyed  in  this  fashion,  there  being  in  extensive  use  a  number  of 
special  forms  of  cop-<tyeing  machines  for  this  purpose. 

2.  Indigo .j^^'^digo  is  probably  the  most  important  and  most  extensively  * 
used  single  dyestuff  both  of  antiquity  and  of  the  present  time.  His- 
torically considered  it  is  one  of  the  oldest  dyestuffs  known,  and  appears  to 
have  been  first  employed  in  India  and  Eg>'pt.  It  was  not  introduced  into 
Europe  until  late  in  the  ^Middle  Ages,  but  previous  to  this  time  another  ^ 
plant  of  the  same  character  known  as  uoad  had  long  been  used  in  dyeing.* 
The  Portuguese  first  introduced  Indigo  into  European  trade  under  the  name 
anil,  a  word  derived  from  the  Sanskrit  name  nila,  meaning  indigo  or  blue. 
It  is  interesting  to  know  that  aniline  thus  derived  its  name  from  Indigo, 
as  it  was  first  prepared  by  the  distillation  of  this  dyestuff. 

The  dyestuff  Indigo  is  derived  from  a  number  of  plants  of  the  indigofera 
or  isatis  varietj'',  but  its  principal  commercial  sources  are  the  following: 
Indigofera  tindoria,  I.  anil,  I.  disperma,  I.  argentia. 

The  coloring  principle  present  in  Indigo  is  known  as  indigotine  or  indigo- 
blue.  The  crude  product  derived  from  the  plant,  however,  contains  sev- 
eral other  bodies  in  varying  amounts,  f  such  as  indirubin  for  indigo-red),  J 

*  Woad  is  still  used  to  some  extent  in  the  preparation  of  certain  vats,  but  only  in 
connection  with  Indigo,  and  never  by  itself. 

t  Of  the  various  associated  substances  in  natural  Indigo,  the  only  one  of  interest  to 
the  dyer  is  the  indigo-red  or  indirubin.     This  may  be  present  to  the  extent  of  15  per  cent. 
It  may  readily  be  isolated  from  the  natural  Indigo  by  treating  first  with  dilute  sulphuric 
acid,  then  with  caustic  potash  and  finally  washing  with  boiling  alcohol.     The  first  two 
treatments  remove  the  indigo-gluten  and  the  indigo-brown,  while  the  indirubin  is  dis- 
solved by  the  boiling  alcohol,  from  whicli  it  precipitates  on  cooling  as  a  reddish  brown 
powder.     With  the  exception  of  its  color  and  its  solubilitj'  in  boiling  alcohol,  indirubin  is 
very  similar  to  Indigo;    like  the  latter  it  dissolves  in  concentrated  sulphuric  acid  and 
Indi^y  be  converted  by  reducing  agents  into  a  leuco-compound  soluble  in  alkalies.     In 
er  words  it  forms  a  vat  like  Indigo,  but  its  reduction  is  slower.     This  explains  why 
■•in  kinds  of  Indigo  having  a  high  content  of  indirubin  are  harder  to  reduce  than 
varieties  of  Indigo  having  less  indirubin.     The  presence  of  indirubin  also  exerts 
Carbazol"'^'  influence  on  indigo,  and  the  same  is  also  true  of  the  indigo-gluten  and  indigo- 
The  presence  of  these  ingredients  makes  the  Indigo  hard;    the  smaller  the 
>  of  these  materials  in  the  Indigo,  the  softer  and  the  more  readilv  powdered  and 
The  color  sh  ,i  ^^e  product  be. 

aaaea,  and  thuj^ggg  noticed  in  heavy  shades  of  Indigo  is  not  due  to  the  presence  of  in- 
liquor  even  to  I  jg  ^^^  ^^  ^j^p  physical  form  of  the  Indigo  particles  deposited  in  the  fiber. 


INDIGO  411 

indigo-brown,  indigo-gluten  and  some  mineral  matters.*  In  the  plant 
itself  the  coloring  matter  is  supposed  to  exist  in  the  form  of  a  glucoside 
called  indican.  The  process  of  extraction  of  the  dyestuff  from  the  plant  is 
both  interesting  and  complicated.  The  indigo  plant,  which  is  a  shrub 
growing  3  to  4  ft.  in  height,  is  cut  in  summer,  f  The  cut  plants  are  tied 
up  in  bundles  and  packed  into  long  vats,  which  are  then  filled  with  water ; 
in  a  short  time  fermentation  sets  in  which  is  allowed  to  continue  for  ten  to 
fifteen  hours.  This  process  converts  the  indican  of  the  plant  into  soluble 
matters  which  are  extracted  from  the  plant  by  the  water  and  pass  into 
solution.  J  The  liquor  is  then  run  into  another  vat,  placed  at  a  lower 
level,  and  here  it  is  churned  and  beaten  up  either  by  hand  or  mechanically 
for  the  purpose  of  exposing  it  to  the  oxidizing  action  of  the  air,  whereby  the 
insoluble  indigotine  is  formed  and  precipitated  out.  This  collects  at  the 
bottom  of  the  vats  in  the  form  of  a  paste  or  mud  which  is  washed,  filtered, 
pressed  into  cakes,  and  dried.  This  constitutes  the  raw  indigo  of  trade, 
and  comes  in  the  form  of  large  cubical  blocks.  The  best  natural  Indigo 
comes  from  Java  and  Bengal,  and  contains  from  60  to  75  per  cent  of  color- 
ing matter.  Madras  Indigo  is  usually  somewhat  inferior,  while  that  from 
Guatemala,  China,  Africa,  and  Egypt  is  very  variable. 

The  raw  indigo  of  trade  is  a  dark  blue,  earthy-looking  substance. 
When  scratched  with  the  finger  nail  good  qualities  will  exhibit  a  coppery 
streak.  At  the  present  time  a  great  deal  of  the  crude  Indigo  undergoes  a 
refining  process,  for  the  purpose  of  eliminating  the  many  impurities  liable 
to  occur  in  the  raw  product;  it  also  comes  into  trade  ready  ground  either 
as  a  powder  or  a  paste  in  order  to  f acihtate  its  use  by  the  dyer.  § 

*  In  the  first  competition  of  synthetic  Indigo  with  the  natural  product,  it  was  claimed 
that  the  presence  of  these  other  bodies  in  the  latter  gave  it  more  desirable  properties 
than  the  synthetic.  Careful  and  unprejudiced  examination  of  these  claims,  however, 
has  demonstrated  the  fact  that  these  associated  bodies  must  be  regarded  solely  as 
impurities  and  have  little  influence  on  the  resulting  color,  as  they  are  practically  all 
eliminated  in  the  wash  waters  after  dyeing  or  are  decomposed  into  inert  bodies  in  the  vat. 
This  fact  is  also  apparent  in  that  refined  Indigo  (from  which  these  bodies  have  been 
removed)  is  preferred  by  the  dyer  to  the  crude  material.  It  seems  to  be  amply  demon- 
strated that  the  sole  value  of  Indigo  is  in  the  indigotine  that  it  contains.  Synthetic 
Indigo,  being  of  a  very  high  degree  of  purity,  usually  gives  somewhat  clearer  and  brighter 
colors  than  the  natural  dye. 

t  Two  crops  are  usually  gathered  from  the  same  plants  each  year. 

J  The  Indigo  is  extracted  chiefly  from  the  leaf  of  the  plant;    this  contains,  on  th 
average,  about  0.5  per  cent  of  coloring  matter. 

§  Before  Indigo  can  be  used  by  the  dyer  for  purposes  of  reduction  it  must  be  gntion 
to  a  very  fine  impalpable  powder.  In  former  times  where  the  natural  Indigo  was  bg  the 
in  the  form  of  blocks  or  lumps  it  had  to  be  ground  in  special  indigo  mills  for  a  lor  j^-,of]_ 
This  accounts  for  the  fact  that  it  is  now  so  much  used  in  the  form  of  a  20  per  ce 
(with  water  or  glycerin).  Synthetic  Indigo  is  practically  altogether  market  have  the 
form  of  such  a  paste,  as  it  is  then  ready  for  direct  use  in  preparing  the  stock  a  the  wool 
indigo-white. 


412 


THE  VAT  DYES 


The  principle  of  indigo  dyeing  has  always  differed  entirely  from  that  of 
other  classes  of  dj^estuffs,  and  has  constituted  an  art  by  itself.  Indigo  is  per- 
fectly insoluble  in  water,  and  hence  cannot  be  applied  in  dyeing  in  this  form. 


Ind> 


Carbazol'^ 


m 


CO 

»— I 

(N 

d 


The  color  sh:;-;tion  of  various  reducing  agents,  however,  it  may  be  converted  into 

added,  and  thigg  known  as  indigo-white,  which  is  soluble  in  alkalies;    in  this 

'^'pplied  to  the  fiber,  and  by  subseciuent  oxidation  by  simple 


INDIGO  VATS  413 

exposure  to  the  atmosphere,  the  iiuhgo-white  is  readily  converted  back  to 
the  insohible  blue  indigotine,  which  thus  remains  permanently  fixed  in  the 
fiber.*  Indigo  may  also  be  converted  into  a  soluble  blue  coloring  matter 
by  treatment  with  strong  sulphuric  acid.  This  body,  known  as  Indigo 
Carmine,  or  indigo  sulphonate,  may  be  classed  as  an  ordinary  acid  dye- 
stuff,  being  applied  in  the  usual  form  of  acid  dyebath;  but  it  does  not 
possess  the  great  fastness  and  other  valuable  properties  of  Indigo  itself. 
3.  Methods  of  Dyeing  Indigo.— rindigo  is  extensively  used  for  both 
wool  and  cotton  dyeing,  though  it  is  being  used  proportionately  less  for 
the  dyeing  of  wool  since  the  introduction  of  the  fast  alizarine  and  anthra- 
cene blue  dyes.  It  is  not  much  employed  for  the  dyeing  of  silk.  In 
calico  printing  it  has  an  extensive  application,  principally  for  discharge 
styles.  Tne  vats  used  for  cotton  dyeing  are  generally  more  strongly 
alkaline  than  those  for  wool,  while  the  proportion  of  Indigo  used  in  them 
is  also  higher.  In  cotton  dyeing,  too,  the  vats  are  usually  worked  cold. 
Indigo  dyemg  is  known  as  "  vat  "  dyeing  because  it  is  carried  out  in  a 
specially  prepared  vat.  According  to  the  character  of  the  reducing 
agent  employed,  these  vats  are  classified  as  follows: 

Zinc  vat,  ^""^  Fermentation  vat, 

Hydrosulphite  vat,  -      Copperas  vat.   . 


The  fermentation  vat  is  the  oldest  form  of  indigo  dyeing,  and  is  still 
used  to  a  considerable  extent  for  wool  dyeing.  Its  action  depends  on  the' 
chemical  activity  of  certain  ferments  which  reduce  the  indigotine  to  the 
soluble  indigo-white. .  This  vat  is  used  warm,  while  the  other  vats  are 
usually  worked  cold.f  ^ 

The  copperas  vat  was  the  earliest  form  of  chemical  vat;  it  was 
exclusively  adopted  for  cotton.  At  the  present  time,  however,  it  is  almost 
obsolete.     The  reducing  agent  employed  was  copperas,  or  ferrous  sulphate. 

The  zinc  vat  was  formerly  the  favorite  one  employed  for  cotton,  and 
even  at  the  present  time  it  is  quite  largely  used.  The  reducing  agent 
employed  is  an  alkaline  solution  of  zinc  dust. 

*  Indigo  is  apparently  fixed  on  the  fiber  mechanically;    that  is  to  say,  the  coloring 
matter  is  deposited  in  the  fiber  in  a  fine  state  of  division;   if  the  color  is  deposited  toe 
rapidly  it  will  lack  fastness,  especially  to  rubbing.     Hence  it  is  not  advisable  to  i^ 
concentrated  vats  for  dyeing  heavy  shades  of  Indigo,  but  to  build  up  the  color  by  m' 
of  several  successive  dips  in  weaker  vats.  .        ^ 

t  Wool  reacts  somewhat  differently  with  the  reduced  Indigo  in  the  vat  than  ^^^^^^ 
The  former,  on  account,  perhaps,  of  its  somewhat  alkaline  character,  has  cons^^  ^he 
affinity  for  the  acid  indigo-white  and  consequently  fairly  deep  shades  of  goodl  mad- 
can  be  obtained  with  one  dip  on  wool.  Cotton  has  much  less  attraction  for  t' 
indigo  and  takes  up  a  much  smaller  quantity  of  the  dye.  It  is  customary,  "'"^  '^^ve  the 
dye  wool  in  the  warm  (fermentation)  vat,  while  cotton  is  dyed  in  a  cold  va"  "^  wool 
for  the  dye  decreases  as  the  temperature  rises. 


414  THE  VAT  DYES 

The  hydrosulphite  vat  is  the  one  of  latest  origin;  it  is  emploj'cd  very 
largely  at  the  present  time  for  all  classes  of  indigo  dyeing  both  on  wool 
and  cotton.     The  reducing  agent  employed  in  this  vat  is  sndjnm  hydro-   '^ 
^^^  siii1pj;\jt,e,  NaHSOo.  prepared  by  the  action  of  zinc  dust  on  sodium  bisul-    i 
phite.     It  is  gradually  replacing  the  other  forms  of  vats  as  it  is  the  most    "^ 
simple  and  scientific  and  the  most  easily  regulated.* 

The  alkali   used  for  dissolving  the  indigo-white  is  the  same  for  all 
forms  of  vats;  it  may  be  either  lime  or  caustic  soda,  or  a  mixture  of  the  ^^ 
two.  depending  upon  whether  the  vat  is  to  be  employed  for  wool  or  cotton 
dyeing.     Ammonia  does  not  appear  to  dissolve  indigo-white  verj'  readily,  f^ 
and  the  alkaline  carbonates  are  still  less  suitable. 

Indigo-white  behaves  Uke  a  very  weak  acid,  and  it  requires  an  excess 
of  rather  strong  caustic  alkali  to  bring  it  into  solution,  and  it  is  readily 
precipitated  again  by  the  addition  of  anj^  acid.  On  this  account  the  vat 
must  always  be  kept  alkaline. 

Before  Indigo  is  introduced  into  the  vat  (of  whatever  variety)  it  must 
be  in  a  very  finely  divided  state,  otherwise  the  reduction  will  always  be 
incomplete.  The  grmding  of  Indigo  is  a  rather  important  consideration; 
it  is  usually  first  ground  in  the  dry  state,  and  then  ground  a  second  time 
with  a  little  water  (to  which  a  small  amount  of  alkali  may  be  added)  to 
the  form  of  a  paste.  Indigo  paste  of  this  character  may  be  purchased  in 
the  market  by  the  dyer,  and  may  be  added  to  the  vat  directlj^;  it  should 
contain  20  per  ceat  of  indigotine. 

During  the  reduction  of  Indigo  in  the  vat,  the  process  is  usually  accom- 
panied with  secondary  chemical  reactions  varying  in  their  nature  and  degree 
with  the  character  of  the  vat.  This  results  in  the  conversion  of  smaller 
or  larger  amounts  of  the  dyestuff  into  substances  other  than  indigo-white 
and  a  resultant  loss  of  coloring  matter.  This  is  especially  large  in  the  cop- 
peras vat,  it  also  amounts  to  considerable  in  the  fermentation  and  zinc 
vats;  in  the  hydrosulphite  vat  it  is  reduced  to  a  minimum  of  about  2  per 
cent. 

Indigo  vats  when  used  for  dyeing  should  not  have  a  concentration 

of  more  than  3  parts  of  indigotine  per  1000  parts  of  liquor.     IMore  than 

this  tends  to  the  production  of  shades  which  are  liable  to  crock  and  also 

' '>se  in  washing.     The  vat  must  also  possess  an  excess  of  reducing  agent. 

,^'s  may  act  in  several  ways.     It  prevents  the  premature  oxidation  of  the 

^i.o-white  arising  from  the  vat  liquor  coming  in  contact  with  the  air  or 
V  Ml  the  pores  of  the  material  being  dyed,  and  so  prevent  or  retard  the 

time  required  for  the  reduction  of  the  Indigo  in  the  various  vats  is  about  as 

The  color  sh: -^i  ,  ,        , 

J  ]    ,        ,  .,'     ''as  vat two  to  three  hours 

added,  and  thi. pp.         ^  r  r-      . 

,■  ,     y^  e  vat four  to  nve  hours 

hquor  even  to  I         .x        x  ,    ,r  , 

'^'p^hite  vat one-half  to  one  hour 


METHOD   OF   DYEING   INDIGO 


411 


penetration  of  the  indigo-white.  Again,  the  more  thoroughly  the  indigo- 
white  in  the  vat  is  reduced  the  more  completely  will  it  work  its  way  into 
the  material  and  the  faster  will  be  the  color.  A  certain  excess  of  reducing 
agent  is  also  of  advantage  in  the  subsequent  oxidation  of  the  indigo-white 
to  indigo-blue,  as  then  the  action  of  the  oxygen  is  slower  and  more  uniform, 
giving  better  penetrated  colors  and  also  causing  the  dyestuff  to  be  pre- 
cipitated in  a  finer  state  of  division,  which  results  in  faster  and  better 
colors.  If  there  is  not  sufficient  excess  of  reducing  agent  in  the  vat,  on 
washing  after  dyeing  and  oxidizing  a  large  part  of  the  color  will  be  removed, 
whereas  if  more  reducing  agent  were  present,  the  loss  on  washing  should  be 
very  little. 


Fig.  217. — Machine  for  Dyeing  Loose  Stock  with  Indigo  and  Vat  Colors. 


The  fastness  of  Indigo  is  said  to  be  improved  by  an  after-treatment  with 
bluestone  and  acetic  acid.  The  use  of  glue  in  the  vat  also  has  the  same 
effect.* 

Indigo  is  frequently  bottomed  by  first  dyeing  with  certain  substantive 
or  sulphur  dyes;  and  indigo  blue  on  cotton  may  be  topped  by  dyeing  with 
basic  colors;  the  goods  after  dyeing  in  the  vat  being  mordanted  with 
tannin,  fixed  with  tartar  emetic  and  dyed. 

Redder  shades  may  be  obtained  with  Indigo  on  cotton  by  steaming 
after  dyeing  in  the  vat,  but  this  somewhat  decreases  the  fastness  to  waa3 
ing.     Heavier  shades  may  be  obtained  by  first  mercerizing  the  co 

ation 
*  Treatment  with  bhiestone  causes  the  shade  to  become  somewhat  gref.pg  |Up  / 
using  the  glue  treatment  it  is  recommended  to  pad  the  cloth  previous  to  dye' i  , 

solution  of  glue  (I5  to  2^  ozs.  per  gallon).    This  causes  the  shade  to  be  b" 
redder  and  increases  the  fastness  to  rubbing.  to  have  the 

By  passing  the  cloth  before  dyeing  through  a  solution  of  Turkey-red  oj  in  the  wool 
the  fastness  to  alkali  and  chlorine  is  much  increased. 


416  THE  VAT  DYES 

by  treatment  with  a  strong  solution  of  caustic  soda.*  The  mercerized 
fiber  shows  a  greater  attraction  for  the  Indigo  than  the  untreated  cotton. 
In  order  to  save  Indigo  it  has  been  suggested  to  mercerize  only  one  side  of 
the  cloth  to  be  dyed,  and  when  this  is  run  through  the  vat  the  mercerized 
side  will  dye  up  much  darker  than  the  other,  f 

With  improvements  in  mechanical  devices  it  has  become  possible  to 
dye  Indigo  on  cotton  in  the  form  of  cops,  tubes,  cheeses,  beamed  warps, 
etc.  In  such  machines  the  material  remains  stationary  and  the  indigo 
vat  liquor  is  forced  through  the  fiber.  Only  the  hydrosulphite  vat  can 
be  used  for  this  purpose  as  there  must  be  no  sediment  or  undissolved  par- 
ticles, because  the  cotton  material  in  this  case  acts  as  a  filter  to  the  liquid. 
Therefore  great  care  must  be  taken  in  preparing  the  vat  for  this  method  of 
dyeing.  Special  apparatus  must  be  used  for  dyeing  Indigo  (and  the  other 
vat  dyes  as  well)  differing  from  that  employed  for  the  ordinary  dyestuffs, 
as  provision  must  be  made  to  draw  air  through  the  dyed  material  in  order 
to  oxidize  the  color. 

In  piece  dyeing  two  forms  of  indigo  vats  are  used :  (a)  immersion  vat, 
and  (b)  continuous  vat.  In  the  first  form  of  vat  sinking  frames  are  used  on 
which  the  goods  are  spirally  attached  ))y  means  of  hooks.  These  frames 
are  immersed  in  the  vat  for  the  required  time,  then  lifted  out  and  exposed 
to  the  air  for  oxidation,  when  another  dip  is  given  until  the  required  depth 
of  color  is  obtained.  Usually  between  each  dip  the  frame  is  turned  bottom 
up  so  as  to  get  even  dyeings.  Immersion  vats  are  chiefly  used  for  heavy 
goods  that  do  not  readily  dye  through,  for  the  frame  may  be  left  in  the 
liquor  for  any  length  of  time  necessary,  whereas  in  continuous  dyeing 
machines  this  is  not  possible.  Heavy  linens,  moleskins,  and  such 
fabrics  are  often  left  in  the  vat  overnight,  or  even  for  several  days  in  order 
to  obtain  proper  penetration.  Immersion  vats  are  also  used  for  goods  to  be 
dyed  on  one  side  of  the  piece  only ;  in  such  a  case  two  pieces  are  fixed  back 
to  back  on  the  frame.  When  the  dyed  pieces  are  exposed  to  the  air  only 
the  outer  sides  are  oxidized  and  the  Indigo  is  chiefly  developed  there,  the 
other  side  being  dyed  a  considerably  lighter  shade.  For  dyeing  on  immer- 
sion frames  the  zinc  vat  is  more  suitable  than  the  hydrosulphite  vat,  as  the 

*  To  produce  full  shades  of  blue  the  Hochst  Co.  recommend  passing  the  goods,  before 
»:'eing  in  the  vat,  through  a  solution  containing  1  to  1'  lbs.  of  starch  to  100  gallons  of 

^^or  producing  very  heavy  shades  of  Indigo  cotton  is  sometimes  first  dyed  with  a 

.niline  Black,  as  follows:  For  100  lbs.  of  cotton  yarn,  work  for  one  hour  at  100"  F. 

.       containing  3^  lbs.  aniline  salt,  85  lbs.  sodium  bichromate,  and  7  lbs.  of  hydro- 

Larbazol       ^^^.  ^yj.i,^g  Qy^  ^gU  j^j^j  treat  in  a  fresh  bath  with  1^  lbs.  of  soda  ash  for  one-half 

°  F.     Then  rinse  twice  and  hydro-extract  and  dj'^e  in  the  indigo  vat.     In 

The  color  sh:  3,  '  coppery  shades  of  blue  may  be  obtained  with  very  little  Indigo.     Instead 

added,  and  thi  pi"  "e  Black  a  light  shade  of  manganese  bronze  maj^  also  be  employed  as  a 


ct 


liquor  even  to  t 


FERMENTATION   VAT 


417 


latter  contains  hydrosiilphite  and  caustic  soda,  which  cannot  be  squeezed 
out  in  this  case  after  dyeing,  and  consequently  uneven  colors  are  liable  to 
result.* 

In  continuous  machines  the  pieces  are  run  through  successive  vats  and 
exposed  to  the  air  for  oxidation  between  the  dips.  Usually  four  to  six 
vats  are  employed  in  one  range  so  as  to  obtain  heavy  shades.  The  hydro- 
sulphite  vat  liquor  is  most  generally  employed  for  this  form  of  continuous 
dyeing,  as  there  is  no  sediment  and  the  vat  is  easily  regulated.     The 


Fig.  218. — Dyeing  Machine  for  Indigo  and  Vat  Dyes.     (Zittauer.) 


depth  of  color  may  be  regulated  by  varying  the  speed  of  running  and  the 
number  of  immersions.  It  is  always  preferable  to  enter  the  goods  in  the 
wet  state.  By  drying  the  goods  first  after  dyeing  and  then  souring  and 
washing  heavier  shades  of  blue  are  obtained. 

^j^i^'Fermentation  Vat. — The  essential  ingredients  of  the  fermentation 
vat  are:  Indigo,  lime,  woad,  bran,  and  madder.  The  woad  furnishes  the 
proper  kind  of  ferment  for  the  reduction  of  the  Indigo,  the  bran  and  mad- 

*  In  dyeing  carbonized  wool  or  shoddy  in  the  indigo  vat  care  must  be  had  to  have  the 
goods  thoroughly  neutrahzed  with  soda  before  entering  the  vat,  as  any  acid  in  the  wool 
may  cause  disturbances  in  the  vat  by  neutrahzing  the  alkali. 


418  THE  VAT  DYES 

der  serve  as  nourishment  for  the  growth  of  the  ferment,  while  the  Ume 
serves  to  neutrahze  the  acids  hberated  during  the  fermentation  and  also 
furnishes  the  alkali  necessary  for  the  solution  of  the  reduced  Indigo. 

There  are,  however,  a  large  variety  of  substances  used  in  the  prepara- 
tion of  the  fermentation  vat,  and  almost  every  indigo  dyer  has  his  own 
special  formula,  but  the  essential  ingredients  are  those  given.  According 
to  the  make-up  of  its  constituents,  the  fermentation  vats  are  classified  as 
follows : 

Wood  vat,  constituted  as  above  outlined. 

Urine  vat,  containing  urine  as  an  active  source  both  of  fermentation  and  alkalinity; 
at  present  almost  obsolete. 

Potash  vat,  in  which  potash  is  used  as  the  chief  alkali. 

Soda  vat,  also  known  as  the  German  vat,  in  which  soda  is  the  chief  alkali  used. 

/ 
In  Eastern  countries  all  manner  of  substances  are  added  to  the  indigo 

vat  for  purposes  of  aiding  the  fermentation  or  supplying  nourishment  to 

the  ferment;   among  some  of  these  substances  may  be  enumerated  dates, 

raisins,  honey,  plant  seeds,  glucose,  etc.* 

(a)  Saxon  vat. — This  is  one  of  the  earliest  forms  of  Indigo  dyeing  in 
Europe,  and  is  still  practiced  in  the  same  primitive  manner  by  the  peasants 
of  Saxony,  where  the  celebrated  Saxon  blue  is  dyed.  The  following  experi- 
ment will  illustrate  this  method :  Take  10  grams  Indigo  paste  (20  per  cent) 
and  mix  with  10  grams  potash  dissolved  in  50  cc.  water;  place  50  grams 
raw  unscoured  wool  in  a  wooden  or  earthenware  vessel,  and  pour  over  it 
the  above  solution,,  sufficiently  diluted  to  just  cover  the  wool.  Set  aside 
in  a  warm  place  for  a  week  or  ton  days.  A  moderate  fermentation  sets 
in  which  causes  the  reduction  of  the  Indigo,  which  is  absorbed  by  the  wool, 
and  thus  the  dyeing  is  accomplished.  When  sufficiently  colored,  remove 
the  wool,  squeeze,  allow  to  oxidize  in  the  air,  and  finally  wash  in  a  soap  solu- 
tion. The  shades  obtained  in  this  manner  are  especially  beautiful,  and 
they  are  highly  prized  on  account  of  their  fastness  to  rubbing. 

(6)  Woad  vat. — It  is  very  difficult  to  obtain  any  very  satisfactory 
results  on  a  small  experimental  scale  with  the  fermentation  vat,  but  the 
following  will  illustrate  the  method  of  setting  this  vat:  Place  6  liters  of 
water  in  a  wooden  or  stoneware  vessel  and  heat  to  about  160°  F. ;  add 
60  grams  of  woad  previously  broken  up  and  soaked  for  several  hours  in  a 
little  warm  water;  next  stir  in  20  grams  bran,  8  grams  soda  ash,  3  grams 
lime,  20  grams  madder,  and  12  grams  Indigo  paste  (20  per  cent).  Stir 
well,  and  then  cover  with  a  cloth  and  allow  to  stand  in  a  warm  place  for 
twenty-four  hours.  During  this  time  the  fermentation  has  become  quite 
active;  the  liquor  should  be  yellowish  in  color  and  be  covered  with  a  light 

*  Cotton  dyed  in  the  fermentation  vat  acquires  a  peculiar  "  indigo  smell  "  which  is 
insisted  upon  by  buyers  in  some  countries. 


THE  WOAD   VAT  419 

blue  froth.  It  should  now  be  stirred  up  well,  and  if  any  large  quantity  of 
gas  is  given  off,  a  little  lime  should  be  added;  after  which  it  is  again  cov- 
ered and  left  to  ferment  for  a  few  hours  more.  When  the  reduction  of  the 
Indigo  is  complete,  the  liquor  of  the  vat  will  be  yellow  in  color  with  the 
surface  covered  with  a  dark  blue  layer,  which  if  skimmed  off  should  be 
granular  in  appearance.  During  dyeing  the  vat  should  be  maintained  at  a 
temperature  of  120°  F.  If  the  vat  does  not  have  a  satisfactory  appearance, 
a  little  more  lime  should  be  added,  the  licjuor  stirred  up,  and  then  covered 
and  allowed  to  stand  for  a  couple  of  hours. 

When  the  vat  has  been  brought  to  a  proper  condition,  steep  a  handful  of 
well-scoured  wool  in  the  liquor  for  a  few  minutes.  On  being  taken  out  the 
wool  should  be  of  a  greenish  yellow  color;  squeeze  and  expose  to  the  air 
until  the  blue  color  is  completely  developed,  then  wash  in  a  warm  soap 
bath.  The  latter  treatment  should  cause  the  wool  to  lose  but  a  small 
amount  of  color.  In  dyeing,  care  should  be  taken  not  to  disturb  the  sedi- 
ment in  the  vat,  otherwise  streaked  and  uneven  colors  will  result.  The 
vat  may  now  be  used  for  dyeing  a  variety  of  woolen  material  (loose  wool, 
tops,  yarn,  and  woven  pieces).  Heavier  shades  may  be  produced  by 
giving  several  dips  in  the  vat,  squeezing  and  oxidizing  in  the  air  after  each 
dip.  Care  should  be  taken  not  to  agitate  the  liquor  too  much,  as  other- 
wise it  will  rapidly  oxidize  and  turn  blue,  and  no  longer  be  fit  for  dyeing. 
The  vat  should  be  contained  in  a  tall-shaped  vessel,  as  about  one-third  of 
the  vat  is  made  up  of  the  sediment  which  it  is  not  desirable  to  disturb  while 
dyeing. 

The  vat  may  be  maintained  continuously  for  a  long  period  of  time. 
After  being  worked  for  some  time  it  becomes  partially  exhausted  and 
oxidized;  then  a  little  glucose  (syrup),  bran,  madder,  and  lime  may  be 
added  together  with  more  Indigo  paste.  It  is  well  stirred  up,  covered 
over,  and  allowed  to  stand  for  several  hours  or  overnight,  when  it  is  again 
ready  for  dj'eing.  For  good  results  the  amount  of  Indigo  in  the  vat  should 
not  rise  above  3  parts  per  1000. 

The  woad  vat  is  also  known  as  the  "  bastard  "  vat,  and  the  proportion 
of  its  ingredients  may  vary  considerably.  On  a  large  scale  the  following 
proportions  are  recommended: 

Content  of  vat  600-800  gallons. 

Woad 50  lbs. 

Bran 20  lbs. 

"^             Soda  ash 8  lbs. 

Lime 3  lbs. 

Madder 20  lbs. 

Indigo  paste  (20  per  cent) 12  lbs 

If  soHd  Indigo  is  used  only  about  2 j  to  4  lbs.  should  be  used ;  but  in  this 
case  the  dyestuff  should  be  verj'  carefully  ground  in  a  ball  or  roller  mill 


420 


THE  VAT  DYES 


THE  SODA  VAT 


421 


for  twenty-four  to  forty-eight  hours  together  with  a  Httle  caustic  soda  and 
water.  This  is  to  insure  its  being  converted  into  an  im palpably  fine  powder, 
otherwise  its  reduction  in  the  vat  uill  be  difficult  and  incomplete. 

(c)  The  soda  vat  does  not  make  use  of  woad,  but  otherwise  it  is  very 
much  the  same  as  the  preceding.     Although  the  amount  of  its  constit- 


\^222^2^^S^m 


Fig.  220.— Indigo  Dyevat  and  Oxidizer.     (Mather  &  Piatt.) 


uents  will  var>^  largel}''  among  different  dyers,  the  following  proportions 
have  been  recommended: 

Contents  of  vat  690-800  gallons. 

Syrup 8  lbs. 

Bran 20  lbs. 

Soda  ash 14  lbs. 

Lime 3  lbs. 

Madder 6  lbs. 

Indigo  paste  (20  per  cent) 12  lbs. 

The  methods  of  preparing  and  working  this  vat  are  in  general  the  same  as 
for  the  woad  vat.  The  objection  to  this  vat  is  the  presence  of  caustic 
soda,  formed  as  a  result  of  the  action  of  the  soda  ash  on  the  lime.  It  does 
not  give  as  full  colors  for  the  same  amount  of  Indigo  as  the  woad  vat;  the 
shades,  however,  are  brighter,  and  this  vat  is  said  to  be  better  suited  for 
the  dyeing  of  light  blues. 

(d)  The  potash  vat  is  analogous  to  the  soda  vat,  with  the  exception  that 
potassium  carbonate  is  used  in  place  of  soda  ash. 

(e)  The  urine  vat  is  practically  obsolete  at  the  present  time;    it  was 


422  THE  \\T  DYES 

prepared  from  stale  tirinp,  salt,  madder,  and  Indigo,  the  alkali  being  sup- 
plied by  the  ammonium  carbonate  present  in  the  stale  urine. 

Properly  to  prepare  and  maintain  a  fermentation  vat  requires  consid- 
erable skill  and  experience,  especially  with  regard  to  the  proper  amounts 
of  and  the  proper  times  for  adding  the  lime.  The  fermentation  must  be 
regulated  in  such  a  manner  as  to  reduce  the  Indigo  sufficiently  by  the  gen- 
eration of  the  proper  amount  of  hydrogen,  and  yet  kept  sufficiently  under 
control  as  to  prevent  the  danger  of  putrid  fermentation  setting  in,  which 
will  result  in  the  rapid  destruction  of  the  Indigo.  When  putrid  fermenta- 
tion starts,  the  vat  is  said  to  have  "  gone  sick,"  and  lime  must  be  added 
and  the  vat  well  stirred  up.  If  the  secondary  fermentation,  however,  has 
gone  too  far  and  cannot  be  stopped  in  this  manner,  the  vat  must  be  boiled 
up  in  order  to  prevent  a  total  loss  of  the  Indigo  therein.  After  this,  of 
course,  the  vat  must  be  set  all  over  again.  The  addition  of  lime  always 
tends  to  reduce  the  fermentation,  if  too  much  is  added  the  fermentation 
may  be  lessened  beyond  that  point  necessary  for  the  complete  reduction 
of  the  Indigo.  If  the  fermentation  is  proceeding  too  slowly  it  maj'  be 
increased  by  the  addition  of  bran.  If  too  little  lime  is  present,  the  acid? 
liberated  by  the  fermentation  will  throw  the  Indigo  out  of  solution,  hence 
the  vat  will  become  weak,  and  bluish  in  color. 

In  dyeing  heavy  shades  with  Indigo  it  is  best  to  build  up  the  color  with 
several  successive  dips  in  weaker  vats,  rather  than  to  dj-e  it  to  the  full  shade 
by  a  single  dip  in  a  very  strong  vat.  In  this  manner  the  pigment  is  more 
thoroughly  absorbed  by  the  fiber  and  will  not  be  so  liable  to  crock  off  as 
otherwise. 

In  using  synthetic  Indigo  the  following  fermentation  vat  is  recom- 
mended: Use  25  lbs.  of  Indigo  paste  (20  per  cent),  12  lbs.  of  bran,  12  lbs. 
of  soda  asii,  and  8  lbs.  of  madder.  The  dye  will  be  reduced  in  about  twenty- 
four  to  thirty-six  hours.  The  liquor  at  first  ha.s  a  muddy  appearance,  this 
gradually  becomes  greenish,  and  after  the  addition  of  lime  shows  a  golden 
yellow  color.  The  fresh  vat  has  a  sickly  smell,  but  this  gradually  dis- 
appears, giving  place  to  a  pungent  odor.  In  order  to  keep  up  the  fermen- 
tation in  the  vat  after  use  an  addition  of  5  ozs.  of  molasses  to  each  pound  of 
indigo  used  is  made. 

5.  The  Copperas  Wax. — This  form  of  indigo  vat  is  not  much  used  at  the 
present  time,  as  it  is  not  very  suitable  for  continuous  dyeing  on  account  of 
the  large  amount  of  sedmient  it  contains.*  The  essential  ingredients  of 
this  vat  are  ferrous  sulphate  and  slaked  lime;  these  react  in  the  following 
manner : 

FeS04  +  Ca(OH)2-Fc(OH)2+CaS04. 

*  The  copperas  vat  was  chiefly  used  for  dyeing  skein  yarn.  Its  chief  advantage  was 
that  it  was  easily  set  and  kept  in  condition.  A  considerable  amount  of  Indigo  is  always 
lost  in  the  copperas  vat,  due  to  over-reduction  and  combination  of  the  dye  with  the 
hydrate  of  iron. 


THE   COPPERAS   VAT 


423 


The  ferrous  hydrate  thus  formed  acts  as  a  reducing  agent  in  the  presence 
of  water: 

2Fe(OH)2+2H20  =  Fe2(OH)6+H2. 

The  indigo-white  formed  by  the  reduction  dissolves  in  the  excess  of  lime 
present.  >  --»''''  ^  -  /-  ^ A.^Jj^^&^^^r^ 

The  vat  employed  should  be  narrow  and  deep  to  accommodate  the  large 
amount  of  sediment  formed.  The  temperature  of  the  vat  should  be  kept 
at  about  70  to  75°  F. 

To  prepare  the  copperas  vat  proceed  as  follows:*  36  grams  of  quick- 
lime are  slaked  to  a  thin  paste  with  water;  vv'hile  warm  stir  in  30  grams 
Indigo  paste  (20  per  cent).  Then  add  30  grams  ferrous  sulphate  (copperas) 
dissolved  in  about  100  cc.  water  at  140°  F.  Then  dilute  with  water  to 
500  cc. 

Have  this  solution  in  a  covered  flask;  allow  to  stand  for  four  to  six 
hours  with  occasional  stirring,  in  which  time  the  liquid  should  have  become 
yellow  in  color  with  a  coppery-looking  bead.  Before  adding  the  stock  vat 
to  the  dyevat,  1  lb.  of  ferrous  sulphate  and  U  to  2  lbs.  of  quicklime  should 
be  added  per  100  gallons  of  water. 

The  copperas  vat  is  also  known  as  the  vitriol  vat.  As  a  rule  it  is  not 
replenished,  but  is  worked  three  times  a  day,  being  well  stirred  after  each 
dyeing.  In  about  ten  days  the  vat  should  be  exhausted.  It  is  mostly 
used  for  yarn  dyeing  and  "  resist  "  dyeing. 

When  cotton  is  dyed  in  a  vat  containing  lime  and  which  has  consider- 
able sediment,  the  material  must  always  be  washed  with  acid  (1  to  2  per 
per  cent  of  sulphuric  or  hydrochloric  acid  is  used)  after  dyeing  in  order  to 
remove  all  particles  of  lime  from  the  fiber,  which  would  otherwise  tender 
the  cotton  on  drying.  After  the  acid  treatment  the  cotton  must  be 
thoroughly  washed. 

Darker  shades  are  obtained  in  this  vat  if  the  yarn  is  dried  before  acidi- 
fying, and  redder  shades  can  be  produced   by  drying  at  a  high  temper- 

*  In  practical  dyeing  various  proportions  have  been  suggested  by  different  authori- 
ties, as  follows : 


Indigo,  Natural 

60  per  cent. 

Pounds. 

Indigo,  Synthetic 

20  jier  cent. 

Pounds. 

Quick  Lime. 
Pounds. 

Ferrous  Sulphate. 
Pounds. 

Vat. 
Gallons. 

20 

80 
25-50 
70 
20 
36 
20 
12 
25 

80 
30-40 

70 
15-19 

24 

16 

10 

20 

400 

400 

400 

400 

60 

40 

20 

50 

20 

20 

20 

30 

16 

8 

25 

424  THE  VAT  DYES 

ature.  Also  l:)y  steaming  the  shade  is  made  more  violet  and  bloomy. 
These  remarks  hold  true  for  cotton  dyed  in  anj-  form  of  vat.*  This  cop- 
pery appearance,  however,  is  changed  by  washing  towards  black. 

It  is  probable  that  Indigo  forms  a  chemical  compound  with  ferrous 
sulphate  and  lime,  and  this  entails  a  considerable  loss  of  dyestuff,  for  under 
the  most  favorable  conditions  only  75  to  80  per  cent  of  the  Indigo  placed 
in  the  vat  can  be  found  again.  A  part  of  the  Indigo  remains  in  the  sedi- 
ment probably  combined  with  ferrous  hydrate. 

In  setting  the  copperas  vat  it  is  customary  to  put  the  Indigo  and  cop- 
peras into  the  tath  first,  and  then  to  add  the  milk-of-lime.  To  save  time, 
however,  and  to  obtain  a  better  reduction  of  the  Indigo  it  is  advisable  to 
prepare  a  stock  vat.  This  may  be  prepared  conveniently  by  mixing  25 
lbs.  of  Indigo  paste  (20  per  cent)  with  20  lbs.  of  copperas  previously  dis- 
solved in  hot  water,  and  then  add  25  lbs.  of  lime  in  the  form  of  a  thin  cream. 
Have  the  temperature  of  the  vat  at  about  120°  F.,  stir  up  well  and  allow 
to  stand  until  fully  reduced,  which  will  require  about  three  hours.  In 
practice  the  vat  is  usually  prepared  in  the  evening  and  allowed  to  stand 
overnight. 

The  dyevat  is  usually  a  stone  or  wooden  circular  vat  6  to  9  ft.  deep 
and  21  to  5  ft.  in  diameter,  and  generally  sunk  into  the  floor  of  the  dj'c- 
house  so  as  to  make  it  convenient  for  working.  In  starting  a  new  vat  the 
necessary  amount  of  water  is  run  in,  and  then  for  each  100  gallons  1  lb.  of 
copperas  and  2  lbs.  of  lime  are  added  in  order  to  coimteract  the  effect  of 
the  oxygen  in  the  water.  The  necessary  amount  of  the  stock  vat  is  then 
added,  the  liquid  stirred  up  and  left  for  two  to  three  hours.  The  liquor 
should  then  be  clear  and  of  a  brownish  amber  color,  and  on  gently  stirring 
it,  dark  blue  streaks  should  appear  with  a  coppery  scum  or  flurry  float  on 
the  surface.  Before  entering  the  goods  to  be  dyed  this  flurry  should  be 
skimmed  off  and  added  to  the  stock  vat. 

If  the  liquor  is  greenish  it  indicates  that  part  of  the  Indigo  is  not  reduced, 
and  more  copperas  has  to  be  added.  If  it  has  a  darkish  appearance 
more  alkali  is  needed  and  additional  lime  is  added.  An  excess  of  either 
copperas  or  lime,  however,  should  be  avoided.  After  a  day's  working 
the  vat  should  be  well  raked  up  and  if  necessary  replenished  by  additions 
from  the  stock  vat.  The  sediment  in  the  copperas  vat  contains  a  consid- 
erable amount  of  Indigo,  hence  this  should  be  saved  and  the  Indigo  recov- 
ered bj'-  treatment  with  hydrochloric  acid. 

*  According  to  the  Badische  Co.  bright  reddish  shades  may  be  obtained  by  pre- 
viously treating  the  cotton  goods  with  bone  ghie.  For  this  purpose  the  goods  are 
run  in  a  solution  containing  2  to  5  parts  of  glue  per  1000  parts  of  water,  squeezed  and 
dyed.  Better  results  are  said  to  be  obtained  if  the  goods  are  dried  before  dyeing. 
This  method  of  treatment  is  especially  recommended  for  dyeing  in  the  hydrosulphite 
vat. 


THE   COPPERAS   VAT 


425 


426 


THE  VAT  DYES 


6.  The  Zinc  Vat. — The  principle  of  this  vat  depends  on  the  property 
of  zinc  dust  to  react  with  slaked  lime  to  form  a  calcium  zincate  and  hydro- 
gen: 

Zn+Ca(0H)2  =  Zn02Ca+H2. 

The  hydrogen  thus  liberated  reduces  the  Indigo  to  indigo-white,  which 
dissolves  in  the  excess  of  lime  present.  There  are  evidences,  however, 
which  go  to  show  that  secondary  reactions  take  place  which  make  the 
chemical  process  a  more  complicated  one  than  that  above  outlined. 

The  zinc  vat  is  still  quite  largely  used  for  the  dyeing  of  cotton.  It 
possesses  less  sediment  than  the  copperas  vat,  and  hence  may  be  used  for 
continuous  dyeing.  The  copperas  vat  contains  about  five  times  as  much 
sediment  as  the  zinc  vat. 

The  zinc  vat  is  run  at  a  temperature  of  110  to  120°  F.  which  consider- 
ably helps  in  the  reduction  of  the  Indigo,  without  injury  to  the  dye. 

The  zinc  vat  may  be  prepared  as  follows  .sy 

20  grams  Indigo  paste  (20  per  cent)  are  stirred  well  with 
4  grams  zinc  dust  and 
40  cc.  water  at  110°  F. 

Then  add  10  grams  quick-lime,  previously  slaked  to  a  soft  paste  and 
allowed  to  cool  to  about  115°  F.  Then  dilute  with  water  at  115°  to  200  cc. 
and  put  in  a  covered  flask.*  Allow  to  stand  for  a  few  hours  with  occa- 
sional stirring  until  the  liquor  is  yellow,  f  If  necessary,  it  ma}^  be  left  over- 
night. Under  these  conditions  the  vat  should  keep  in  good  condition  for  a 
long  time.  During  the  dyeing  process  it  is  necessary  to  sharpen  the  vat 
from  time  to  time  by  further  addition  of  zinc  dust  and  lime.  No  fixed 
rule  for  this  can  be  given,  but  for  a  vat  of  100  gallons  about  \  to  1  lb.  of 
lime  and  i  to  |  lb.  of  zinc  dust  will  be  required  each  evening.  Narrow  and 
deep  cement  vats  or  wooden  vats  lined  with  cement  are  best  for  use.  Iron 
vats  may  also  be  employed.     A  standard  solution  of  reduced  Indigo  may 

*  The  following  proportions  have  been  suggested  for  practical  dyeing. 


Indigo,  Natural 

60  per  cent. 

Pounds. 

Indigo,  Synthetic 

20  per  cent. 

Pounds. 

Quick-lime. 
Pounds. 

Zinc  Dust. 
Pounds. 

Vat. 
Gallons. 

2 

1 
5 
31 
2i 
\\ 
4-5 
5-6 

1 
2 
li 
1 

li 
li 

100 
100 
100 
100 
100 
100 
100 

4 

2 

1 

\ 

10 
121 

t  The  stock  vat  should  contain  2  to  2^  per  cent  of  actual  dyestuff,  while  the  vat  used 
in  dyeing  should  contain  2  to  3  parts  of  Indigo  per  1000  parts  of  dye  liquor. 


THE   HYDROSULPHITE   VAT  427 

be  prepared  from  which  the  vat  is  fed  from  time  to  time  as  it  becomes 
exhausted.  During  the  working  of  the  vat  it  should  be  kept  at  a  tempera- 
ture of  about  70°  F. 

The  dyeings  should  be  acidified  with  water  containing  2  grams  sul- 
phuric acid  per  liter  (2  lbs.  per  100  gallons  water),  then  well  rinsed  and 
soaped. 

In  preparing  a  stock  vat  with  synthetic  Indigo  it  is  recommended  to 
mix  25  lbs.  of  Indigo  paste  (20  per  cent)  with  20  lbs.  of  slaked  lime  made 
into  a  thin  cream,  and  then  to  add  3  lbs.  of  zinc  dust  previously  mixed  to  a 
fine  paste  with  2  gallons  of  water  at  120°  F.  Stir  well  and  allow  to  stand 
for  five  to  six  hours.  The  initial  temperature  should  be  115°  F.  In 
preparing  the  dyevat  first  add  5  ozs.  of  zinc  dust  and  1  lb.  of  lime  for  each 
100  gallons  of  water;  stir  up  and  allow  to  stand  for  one  hour  and  then  add 
the  necessary  amount  of  the  stock  vat.  Sometimes  iron  turnings  are  added 
to  the  vat  to  liberate  the  hydrogen  retained  in  the  sediment,  and  to  accel- 
erate the  clearing  of  the  liquor.  If  an  excess  of  zinc  is  present  the  vat  will 
be  muddy  and  frothy,  due  to  too  much  hydrogen  being  generated;  under 
such  circumstances  the  vat  should  be  raked  up  and  more  Indigo  added. 
When  in  good  condition  the  zinc  vat  looks  very  similar  to  the  copperas  vat, 
the  liquor  being  clear  and  of  an  amber-yellow  color  with  flurries  and  blue 
streaks  showing  when  disturbed. 

'y?.  The  Hydrosulphite  Vat. — When  zinc  dust  acts  on  a  solution  of 
sodium  bisulphite,  the  following  reaction  takes  place: 

Zn + 3NaK303  =  NaHS02 + Zn  (NaSOs  )2 + H2O. 

The  body  represented  by  the  formula  NaHS02  is  known  as  sodium  hydro- 
sulphite  and  is  a  strong  reducing  agent,  being  itself  thereby  oxidized  to 
sodium  bisulphite,  NaHSOs,  and  finally  to  sodium  bisulphate,  NaHS04. 
Sodium  hydrosulphite  in  alkaline  solution  very  rapidly  reduces  Indigo 
giving  a  clear  solution  of  indigo-white.  The  sodium  hydrosulphite  liquor 
is  usually  prepared  as  occasion  requires  for  adding  to  the  indigo  vat. 
y  (a)  Concentrated  hydrosulphite  liquor  may  be  prepared  in  the  following 
manner: 

130  grams  zinc  dust. 
55  cc.  water. 

Make  into  a  paste  and  mix  with  1000  cc.  sodium  bisulphite  solution  of 
72°  Tw.  As  the  mixture  becomes  very  warm,  the  temperature  should  be 
kept  down  to  100°  F.  by  the  addition  of  ice  or  cold  water;  after  the  action 
has  ceased  dilute  to  2  liters.  Allow  to  stand  for  one  hour;  then  stir  in 
600  cc.  of  20  per  cent  milk-of-lime  cold  and  allow  to  stand  for  two  hours.* 

*  The  following  process  is  also  recommended  for  the  preparation  of  hydrosulphite 
liquor:  To  100  liters  of  sodium  bisulphite  solution  (72°  Tw.)  add  60  liters  of  water;  then 


428  THE  VAT  DYES 

This  causes  the  precipitation  of  all  the  dissolved  zinc  as  zins  hydrate. 
The  liquor  is  now  strained  to  free  it  from  sediment,  and  preserved  in  a  closed 
bottle.  The  hydrosulphite  solution  thus  prepared  will  keep  intact  for 
several  weeks,  and  the  addition  of  a  small  quantity  of  caustic  soda  will 
cause  it  to  keep  better. 

(6)  Preparation  of  the  staiidard  Indigo  solution. 

75  grams  Indigo  paste  (20  per  cent). 
40  cc.  hot  water. 
90  cc.  caustic  soda,  42°  Tw. 
200  cc.  hydrosulphite  Hquor. 

Stir  gently  and  keep  the  temperature  at  about  110°  F.*  To  complete  the 
process  thoroughly  it  may  be  necessary  to  add  a  little  more  of  the  hydro- 
sulphite solution.  The  liquor  should  then  be  clear  and  yellow  in  color, 
and  a  drop  running  on  a  sheet  of  glass  should  require  about  twenty-five 
seconds  to  turn  blue.f 

(c)  Preparation  of  the  vat. — To  1  liter  of  water  at  about  70°  F.  add  10  cc. 
of  the  hydrosulphite  solution;  allow  to  stand  for  a  short  while,  then  run 
in  about  100  cc.  of  the  standard  Indigo  solution  by  means  of  a  long-tubed 
funnel  ;t  stir  gently,  and  allow  to  stand  for  one-half  hour,  when  the  vat 
is  ready  to  be  used  for  dyeing.  The  liquor  should  be  clear  and  yellow  in 
color. 

The  hydrosulphite  vat  is  especially  well  adapted  for  the  dyeing  of  piece- 
goods  in  the  continuous  vat  and  the  machine  dyeing  of  cops,  etc.,  as  there 
is  no  sediment  formed  in  the  vat,  and  excess  of  hydrosulphite  does  not 
destroy  the  Indigo.     It  is  not  as  much  used  for  skein  yarn.§     There  is  less 

slowly  stir  in  this  13§  kilos,  of  zinc  dust  which  has  previously  been  made  into  a  paste 
with  15  liters  of  water.  The  temperature  should  be  kept  below  85°  F.,  using  ice  if  neces- 
sary. Allow  to  stand  for  two  hours;  then  mix  into  the  clear  solution  50  liters  of  milk-of- 
lime  (20  per  cent),  and  allow  to  stand  for  six  to  twelve  hours.  Decant  the  clear  liquor 
for  use;  it  should  show  a  density  of  25  to  26°  Tw. 

*  In  practice  it  is  best  to  mix  the  Indigo  with  the  caustic  soda  lye,  heat  to  about 
120°  F.,  and  then  add  the  hydrosulphite. 

t  The  Badische  Co.  recommends  the  following  proportions:  100  lbs.  Indigo  (20  per 
cent),  6  gallons  caustic  soda  lye  (76°  Tw.)  and  17  lbs.  hydrosulphite  cone,  powder.  Or  if 
the  dj'er  wishes  to  make  his  own  hydrosulphite,  100  lbs.  Indigo  (20  per  cent),  8  lbs. 
zinc  dust,  8  gallons  sodium  bisulphite  (57°  Tw.)  and  30  lbs.  quicklime  (or  6  gallons  caus- 
tic soda  lye,  76°  Tw.)  for  100  gallons  stock  solution. 

X  In  preparing  a  200-gallon  vat,  first  add  to  the  water  2  ozs.  hydrosulphite  cone, 
powder  (or  2  lbs.  Hydrosulphite  O),  stir  and  allow  to  stand  for  a  few  hours.  Then 
run  in  the  stock  Indigo  solution.  The  vat  exhausts  very  slowly  if  an  excess  of  either 
hydrosulphite  or  caustic  soda  is  present. 

§  The  Badische  Co.  recommends  a  special  hydrosulphite-ammonia  vat  for  dyeing 
cotton  skein  yarn,  as  it  has  no  injurious  action  on  the  workmen's  hands.  It  forms  no 
sediment  and  the  yarn  requires  no  souring  after  dyeing.  To  prepare  a  vat  for  100  lbs 
of  cotton  yarn  to  be  dyed  a  medium  blue  in  two  dips:   Dye  liquor  180  to  220  gallons; 


THE   HYDROSULPHITE   VAT 


429 


Indigo  wasted  in  the  hydrosulphite  vat  than  in  the  other  forms  of  indigo 
dyeing.  The  following  shows  the  amount  of  Indigo  lost  in  the  different 
vats  used  in  cotton  dyeing: 

Copperas  vat 25  per  cent 

Zinc  vat 10  per  cent 

Hydrosulphite  vat 1  to  2  per  cent 

The  Hochst  Co.  recommends  the  following  method  for  preparing  a 
stock  vat:  Mix  25  lbs.  of  Indigo  paste  (20  per  cent)  with  1  gallon  of  luke- 
warm water,  then  add  1|  gallons  of  caustic  soda  lye  (76°  Tw.);  stir  well, 
heat  to  120°  F.  and  then  add  6  lbs.  of  hydrosulphite  cone,  pov/der  pre- 
viously dissolved  in  cold  water.  The  temperature  of  the  vat  should  be 
kept  at  about  120°  F.,  and  if  the  color  of  the  liquid  does  not  become 


Fig, 


•mmmmmmmmmmmmmmm 

222. — Dipping  Apparatus  for  Indigo  Vat 


yellow  after  standing  one  hour  a  further  addition  of  hydrosulphite  must  be 
made.  In  starting  a  new  dyevat  first  add  1^  ozs.  of  hydrosulphite  for  each 
100  gallons  of  water,  stir  up  and  allow  to  stand  for  two  hours,  then  add 

the  cold  liquor  is  previously  "  sprung  "  with  4  ozs.  hydrosulphite  cone,  powder,  \  pint 
caustic  soda  (42°  Tw.),  1  gallon  Turkey-red  oil,  and  9  lbs.  salt.  The  stock  vat  to  be 
added  is  prepared  as  follows:  24  lbs.  Indigo  (20  per  cent),  9  gallons  boiling  water,  \\ 
gallons  caustic  soda  (42°  Tw.),  5}  ozs.  hydrosulphite  cone,  powder  and  2  pints  of  ammo- 
nia''water.  The  mixture  is  allowed  to  stand  for  one-half  hour,  and  dyeing  may  be 
commenced  as  soon  as  the  stock  vat  is  st'  e  into  the  dyevat.  The  skeins  should  be 
suspended  on  bent  iron  rods  so  as  to  be  completely  beneath  the  surface  of  the  liquor. 
The  hanks  are  turned  several  times  during  about  one-half  hour  and  then  taken  out. 
Each  hank  should  be  wrung  out  separately,  allowed  to  o.xidize  in  the  air,  then  rinsed 
but  not  soured.  The  liquor  should  be  of  a  yellow  or  greenish  yellow  color,  and  should 
always  smell  slightly  of  ammonia.  The  common  salt  causes  the  Indigo  to  go  more 
quickly  on  the  fiber.     This  vat  is  also  suitable  for  dyeing  loose  cotton. 


430  THE  VAT  DYES 

the  required  quantity  of  the  stock  vat;  stir  again  and  allow  to  stand  for 
three  hours,  after  which  the  dyeing  may  be  commenced.* 

A  modification  of  the  hydrosulphite  vat  is  known  as  the  Zinc-Bisul- 
phite Vat.  In  this  vat,  instead  of  using  the  ready-made  hydrosulphite, 
the  latter  is  formed  in  the  vat  itself.  The  stock  vat  may  be  made  as  fol- 
lows :  Mix  25  lbs.  of  Indigo  paste  (20  per  cent)  with  2  gallons  of  water, 
and  add  1^  gallons  of  sodium  bisulphite  solution  (72°  Tw.) ;  stir  well  and 
add  2 1  lbs.  of  zinc  dust,  previously  made  into  a  thin  cream  with  warm  water. 
Stir  for  one-half  hour  and  after  standing  for  one-half  hour  add  1|  gallons  of 
caustic  soda  lye  (76°  Tw.),  then  make  up  to  about  16  gallons.  The 
initial  temperature  of  this  stock  vat  should  be  about  120°  F.  The  reduc- 
tion is  complete  as  soon  as  the  liquor  shows  a  golden-yellow  color,  which 
requires  about  one-half  hour  after  the  soda  has  been  added.  In  prepar- 
ing a  fresh  dye  vat  first  add  for  500  gallons  of  water  a  mixture  of  1  pint  of 
sodium  bisulphite  solution  (67°  Tw.),  3  pints  of  water,  and  2  ozs.  of  zinc 
dust.  Stir  up  for  ten  minutes  and  allow  to  stand  for  twenty  minutes, 
when  the  odor  of  sulphurous  acid  will  have  disappeared.  Add  this  to  the 
vat;  stir  and  add  |  pint  of  soda  lye  (76°  Tw.).  After  raking  allow  to  stand 
for  one  hour,  then  add  the  necessary  quantity  of  stock  vat. 

The  hydrosulphite  vat  is  also  free  from  sediment  and  the  reducing 
agent  is  in  the  solution  itself  and  not  in  a  bulky  precipitate  at  the  bottom 
of  the  vat,  as  is  the  case  with  all  other  vats,  f  If  the  vat  becomes  oxidized 
and  turns  blue  owing  to  precipitation  of  indigo,  all  that  is  necessary  is  to 
add  a  fresh  amount  of  hydrosulphite  liquor;  to  maintain  the  proper 
strength  of  the  vat,  fresh  additions  of  the  standard  indigo  solution  are  made 
from  time  to  time  as  needed.  As  the  vat  is  free  from  sediment  the  dyed 
pieces  do  not  require  to  be  passed  through  an  acid  bath  before  washing. 

Cotton  yarn  is  mostly  dyed  with  Indigo  in  the  form  of  warps  in  special 
forms  of  machines  suited  to  this  purpose.  Cotton  piece-goods  are  also 
largely  dyed  with  Indigo  in  special  machines.  These  machines  are  so 
arranged  that  the  goods  are  run  beneath  the  liquor  until  thoroughly 
impregnated,  after  which  they  are  exposed  to  the  air  for  oxidation  and 
then  washed.  In  continuous  dyeing  machines  arrangement  is  made  for 
several  dips  with  alternate  air  oxidation. 

*  A  quick  process  for  the  dyeing  of  Indigo  on  cotton  is  given  by  Brown  (Jour.  Soc. 
Dyers  &  Col,  1913,  p.  71).  A  hydrosulphite  vat  is  used  but  much  less  caustic  soda  is 
employed  than  is  usually  considered  necessary,  and  an  addition  of  common  salt  or 
glaubersalt  is  made.  The  vat  is  prepared  as  follows :  For  100  lbs.  of  yarn  use  200  gallons 
water,  44  lbs.  Indigo  solution  (20  per  cent),  4^  pints  caustic  soda  (42°  Tw.),  ih  lbs. 
hydrosulphite  powder,  cone,  7  pints  Monopol  soap  and  9  lbs.  common  salt  (or  22  lbs. 
glaubersalt) . 

t  It  is  very  important  properly  to  adjust  the  amount  of  alkali  in  the  vat;  as  an  excess 
of  alkali  prevents  the  absorption  of  the  Indigo  by  the  fiber,  while  a  deficiency  of  alkali 
may  cause  dull  and  uneven  shades. 


INDIGO  EXTRACT  431 

The  largest  use  of  Indigo  is  for  the  dyeing  of  warps  for  blue  denim  for 
over-alls  and  other  cheap  cotton  fabrics. 

8.  Indigo  Extract. — As/previously  shown,  when  Indigo  is  treated  with 
strong  sulphuric  acid,  a  soluble  sulphuric  acid  of  Indigo  is  formed.  This 
product  is  used  as  a  blue  acid  dyestuff  under  the  name  of  Indigo  Extract, 
Indigo  Carmine,  Indigotine,  etc. '-^  The  action  of  the  sulphuric  acid  on  the 
Indigo  is  to  form  mono-  and  disulphonic  acids;  when  a  moderate  pro- 
portion of  acid  is  used  and  allowed  to  act  for  a  short  time,  the  mono- 
sulphuric  acid  is  the  principal  product.  This  compound,  after  being 
converted  into  its  sodium  salt  is  known  as  red  or  purple  indigo  extract. 
The  disulphonic  acid,  however,  is  the  one  which  finds  the  most  extended 
application;  it  may  be  prepared  in  the  following  manner:  Mix  10  grams  of 
Indigo  powder  with  40  grams  of  weak  fuming  sulphuric  acid,  or  80  grams  of 
sulphuric  acid  168°  Tw.  Do  not  allow  the  temperature  to  rise  over  120°  F. 
After  careful  stirring  allow  the  mixture  to  stand  for  twelve  hours  at  a  tem- 
perature of  120°  F.  The  thick  liquid  mass  so  obtained  is  soluble  in  water, 
and  may  be  used  in  this  form  as  a  dyestuff,  it  being  known  as  chemic  or 
Saxony  Blue.  Usually,  however,  it  receives  further  treatment;  dilute 
with  twice  its  volume  of  water,  and  add  a  saturated  solution  of  common 
salt  to  precipitate  the  coloring  matter.  Filter  off  the  product,  which  is 
known  as  acid  indigo  extract.  By  dissolving  this  in  water  and  repeat- 
ing the  operations  several  times  in  order  completely  to  remove  the  free 
acid,  a  neutral  or  sweet  extract  of  indigo  is  obtained.  The  best  extract  is 
obtained  from  purified  or  synthetic  Indigo;  that  prepared  from  raw  Indigo 
gives  dirty  greenish  gray  shades.  Soluble  Indigo  is  the  best  refined  extract; 
it  should  freely  dissolve  in  water  without  leaving  any  residue,  and  should 
be  free  from  any  green  impurities.  The  raw  Indigo  used  for  the  manu- 
facture of  extracts  is  first  refined  by  reducing  with  a  concentrated  copperas- 
lime  vat,  allowing  all  insoluble  matters  to  subside,  and  then  allowing  the 
clear  liquor  to  pass  through  shallow  troughs,  which  again  reprecipitate  the 
Indigo  from  solution  by  oxidation. 

9.  Synthetic  Indigo.^^^^wing  to  the  great  importance  of  Indigo  as  a 
dyestuff  it  was  long  the  ambition  of  chemists  to  produce  it  synthetically. 
Its  composition  and  chemical  constitution  were  the  subject  of  extensive 
and  numerous  investigations  by  many  chemists.  By  a  study  of  its  chem- 
ical reactions  and  the  decomposition  products  obtained  from  it  under 
various  treatments,  its  chemical  constitution  finally  became  known. 
The  chemical  formula  of  Indigo  is  rather  complicated,  but  it  has  been 
definitely  established  as 

/C0\  /CO 


C6H4^  ^C  =  C<  >C6H4. 


432 


THE  VAT  BYES 


Having  once  established  its  proper  constitution  it  was  not  long  before 
Indigo  was  s}Tithctically  prepared  in  the  laboratory.  Then  followed  a 
long  number  of  years  of  the  closest  investigation  in  order  to  discover  a 


ci 

o 


-^,'/   > 


a 
IB 


Q 

a, 
o 


03 


suitable  process  of  manufacture  which  would  be  commercially  available. 
In  the  year  1897  synthetic  Indigo  first  came  upon  the  market  as  a  commer- 
cial commodity,  and  since  then  it  has  gradually  displaced  the  natural 


SYNTHETIC   INDIGO  433 

Indigo  from  trade.  With  the  outl^reak  of  the  European  War  and  the 
consequent  cuttin|j;  off  of  the  main  supphes  of  synthetic  Indigo,  resource 
was  once  more  had  to  the  natural  prochict ;  but  at  the  present  time  with  the 
hirge  production  of  the  synthetic  dye  in  all  the  principal  countries,  it  would 
seem  that  the  cultivation  of  natural  Indigo  was  surely  doomed  to  early 
extinction. 

The  first  commercially  successful  process  for  the  production  of  syn- 
thetic Indigo  was  that  employing  naphthalene  as  the  starting  point, 
converting  this  into  phthalic  acid  by  oxidation,  which  is  then  converted 
into  a  phenylglycine  derivative  and  thence  into  Indigo.*  More  recently, 
however,  aniline  has  been  used  as  the  starting  point,  the  phenylglycine 
being  prepared  from  this.  The  Indigo  manufactured  in  this  country  and 
Englajid  is  all  made  by  the  aniline  method. 

*%iithetic  Iflidigo  can  be  made  cheaper,  purer  and  more  uniform  than 
the  Indigo  derived  from  the  plant  and  it  is  identical  with  the  natural 
product  in  all  its  properties  and  qualities.  It^^e'arly  always  marketed 
in  the  form  of  a  20  per  cent  paste  for  the  convenience  of  the  dyer,  as  in  this 
form  it  is  ready  for  use  in  the  preparation  of  the  vat,  whereas  if  in  the  solid 
dry  form  it  would  have  to  be  subjected  to  a  long  and  tedious  grinding 

A  reduced  solution  of  Indigo  has  been  brought  out  on  the  market  con- 
sisting really  of  a  concentrated  stock  vat  of  indigo-white.  It  is  known  as 
Indigo  Solution,  Indigo  White,  or  Indigo  Vat.f  It  was  prepared  in  this 
form  for  the  convenience  of  the  dyer,  who  was  thus  relieved  of  the  burden 
of  reducing  the  Indigo  first.  The  preparation  of  the  vat  when  using  these- 
products  is  much  simplified,  J  but  owing  to  the  extreme  readiness  with 
which  the  reduced  Indigo  oxidizes  it  is  difficult  to  keep  these  products  in  a 
satisfactory  condition. § 

*  In  the  conversion  of  phenylglycine  into  Indigo  much  better  yields  are  obtained 
by  the  use  of  sodamide.  This  may  be  prepared  by  the  action  of  ammonia  on  sodium, 
or  directly  in  the  reaction  mixture  of  sodium  and  the  sodium  salt  of  phenylglycine. 
Sodium  anilide  (CsHsNHNa)  is  also  used  in  the  Indigo  synthesis  in  the  same  manner 
as  sodamide. 

t  Indigo  Solution  and  Indigo  White  are  preparations  containing  20  per  cent  of  Indigo, 
whereas  Indigo  Vat  contains  60  per  cent. 

X  The  following  is  an  example  of  a  1000-gallon  vat  of  medium  strength:  the  water  is 
heated  to  120°  F.  and  there  is  added  4  pints  of  ammonia  water,  and  2^  lbs.  of  hydro- 
sulphite  powder.  When  this  has  been  well  stirred  up  3  gallons  of  glue  solution  (1:10) 
and  19  pints  of  Indigo  Solution  (  =  26  lbs.)  are  added.  The  vat  is  well  stirred  and  allowed 
to  stand  for  fifteen  minutes,  when  the  liquor  should  be  of  a  clear  greenish  yellow  color 
with  a  blue  scum  on  the  surface.  When  the  vat  on  working  becomes  bluish  green  in 
color,  stir  in  \  lb.  more  of  hydrosulphite  powder.  The  strength  of  the  vat  is  replenished 
as  required  by  adding  the  necessary  amount  of  Indigo  Solution.  When  working  regu- 
larly a  daily  addition  of  1  to  2  pints  of  ammonia  water  is  made,  and  a  gallon  of  the  glue 
solution  is  added  twice  weekly. 

§  Indophenol  is  a  product  which  maj'^  also  be  classed  as  a  vat  dye,  as  it  may  be 


434 


THE  VAT  DYES 


Indigo  Salt  is  a  product-  which  was  formerly  used  somewhat  in  calico- 
printing.  It  is  a  bisulphite  compound  of  ortho-nitro-benzaldehyde,  which 
on  treatment  with  dilute  caustic  soda  is  converted  into  indigotine. 

Indophor  is  another  indigo  product  which  had  some  vogue  in  printing. 


Phenylglycine 


Melt  with 
Sodium  Oxide 


Napthalene 


Oxidation  with 

Mercury  and 
Sulphuric  Acid 

A. 


Fig.  224.— Syntheses  of  Indigo.     (Ramsey  &  Weston,  Artifidal  Dyestuffs.) 

It  is  a  mixture  of  indoxyl  and  indoxylic  acid;  when  steamed  it  is  con- 
verted into  Indigo. 

reduced  like  Indigo  and  dyed  from  a  vat.  At  the  present  time  it  has  but  little  use, 
though  formerly  it  was  used  somewhat  as  an  addition  to  the  indigo  vat,  chiefly  in  the 
copperas  vat.  It  is  made  by  the  action  of  alpha-naphthol  on  nitroso-dimethylanihne. 
When  treated  with  an  alkaline  reducing  agent  it  is  converted  into  indophenol  white. 
The  blue  color  is  developed  by  oxidation  in  the  air  or  by  treatment  with  a  dilute  solution 
of  chrome. 


TESTS   FOR  INDIGO  435 

When  Indigo  is^treated  with  oxidizing  agents  (nitric  acid,  chromic  acid, 
etc.),  it  is  converted  into  isatin.  This  reaction  is  employed  technically 
in  the  discharging  of  Indigo  on  printed  cloth,  and  in  the  analysis  of  Indigo 
(by  titration  with  permanganate). 

10.  Testing  for  Indigo  on  the  Fiber. — As  Indigo  is  a  substantive  dye-.^i^--' 
stuff,  and  requires  no  mordant,  a  pure  dyed  indigo  fabric  should  not  show    ^^ 
the  presence  of  any  of  the  common  mordant  metals  in  the  ash  obtained  by      ^ 
ignition.     The  presence  of  the  oxides  of  chromium,  aluminium,  iron,  or  tin,     ^ 
etc.,  in  the  ash  would  indicate  that  the  fabric  also  contained  Logwood  or       ^ 
other  mordant  dyestuff .    Indigo  Extract  may  readily  be  distinguished  from 
vat-dyed  Indigo  by  boiling  a  sample  of  the  dyed  woolen  material  with  a 
one-half  per  cent  solution  of  sodium  carbonate,  whereon  the  extract  will 
have  its  color  partially  removed,  and  on  acidifying  the  solution  with  acid 
the  color  becomes  intensified;    and  finally  the  latter  may  be  decolorized 
with  potassium  permanganate.     A  fabric  dyed  with  pure  vat  Indigo  is  *— - 
not  affected  by  hydrochloric  acid,  dilute  sulphuric  acid,  soap,  alkalies,  or 
cold  alcohol.     Hot  alcohol  extracts  a  little  of  the  blue  color  which  it 
deposits  on  cooling.     Hot  aniline,  amyl  alcohol,  chloroform,  and  nitro- 
benzene extract  the  color  to  a  greater  extent.     Cold  concentrated  sulphuric  />^ 
acid  gives  a  yellow  liquid,  which  quickly  becomes  olive,  and  slowly  changes 
from  a  green  to  a  deep  blue,  due  to  the  formation  of  Indigo  Extract;  on 
adding  water  the  solution  remains  blue,  and  will  dye  a  piece  of  white  wool. 

Table  of  Tests. — (a)'^akeasampleof  cloth  dyed  with  vat  Indigo  and  place  on  it  a 
drop  of  concentrated  nitric  acid;  a  yellow  spot  will  be  formed  surrounded  by  a  green  ring. 
If  the  spot  appears  more  or  less  red,  it  is  usually  a  sign  that  other  coloring  matters  are 
present.  This  nitric  acid  test,  so  generally  employed  by  merchants  for  the  testing  of 
Indigo  dyed  material,  has  not  the  great  value  usually  attached  to  it,  as  there  are  a  number 
of  other  dyestuffs  now  made  which  will  yield  the  same  reaction  practically,  though  some, 
such  as  Alizarine  Blue  and  Azo  Acid  Magenta,  give  the  yellow  spot  without  the  green 
ring;  but  it  is  hard  to  discriminate  closely  between  them. 

(i>)^Take  a  sample  of  vat-dyed  Indigo  cloth  and  immerse  it  in  a  hot  dilute  solution 
of  hydrochloric  acid;  it  will  remain  blue.  Repeat  the  test,  using  a  piece  of  cloth  dyed 
with  Logwood,  and  the  sample  will  become  red.  This  serves  as  a  good  test  to  distinguish 
between  Indigo  and  Logwood,  but  as  a  general  test  for  Indi  ^o  it  is  not  accurate,  as  there 
are  a  number  of  other  blue  dyes  which  behave  in  a  similar  manner. 

^ ,  (c)^oil  a  sample  of  Indigo-dyed  cloth  in  a  clear  solution  of  aniline  oil ;  a  blue  solution 
will  be  obtained,  if  the  oil  is  very  clear,  or  a  bluish  green  solution  if  the  aniline  has  a 
yellow  color.  The  color  appears  red  in  gaslight.  On  adding  hydrochloric  acid  to  the 
solution  and  diluting  with  water,  the  Indigo  will  be  precipitated.  There  are  a  few  of 
the  aniline  dyes  which  are  also  extracted  with  aniline,  but  Alizarines  and  the  wood  colors 
are  not  dissolved  by  this  reagent. 

(dy-T^^reat  a  piece  of  Indigo-dyed  cloth  with  some  concentrated  sulphuric  acid;  an 
olive-green  green  solution  results.  Warm  and  the  solution  will  turn  blue;  dilute  with 
water  and  the  blue  color  remains,  but  on  neutralizing  with  caustic  soda  the  solution 
becomes  yellow. 

(ejtleat  a  piece  of  Indigo-dyed  cloth  in  a  test-tube  in  a  careful  manner  so  as  not  to 


436  THE  VAT  DYES 

ignite  the  material;  viclet-colored  vapors  of  Indigo  will  be  noticed  which  will  give  a 
deposit  of  Indigo  on  the  cooler  part  of  the  tube.  This  test  must  be  carefully  carried  out, 
but  when  properly  done  is  an  excellent  crucial  test  for  Indigo,  and  is  especially  applicable 
to  cotton  goods  containing  only  a  small  amount  of  Indigo. 

(/)  Woolen  material  dyed  with  vat  Indigo  only  should  satisfy  the  following  tests: 
When  steeped  in  cold  or  hot  water  for  ten  hours  no  color  should  be  extracted.  Alcohol 
of  both  50  per  cent  and  95  per  cent  strength  should  not  extract  any  color  even  on  gently 
warming.  A  cold  saturated  solution  of  oxalic  acid  even  on  boiling  should  have  no 
effect;  Logwood  will  be  turned  red.  A  saturated  solution  of  borax  should  have  no  effect 
even  on  boiling;  Indigo  Extract  will  be  extracted.  A  10  per  cent  solution  of  alum  on 
boiling  should  not  be  colored.  Also  ammonium  molybdate  dissolved  in  2  parts  water 
should  extract  no  color.  Prussian  Blue  is  indicated  by  boihng  with  borax  and  adding 
ferric  chloride  when  a  blue  color  will  be  formed.  The  blue  color  of  Indigo  should  be  com- 
pletely' destroyed  on  warming  with  a  hydrochloric  acid  solution  of  stannous  chloride  or 
ferric  chloride.  Glacial  acetic  acid  will  entirely  remove  Indigo  from  the  fiber  by  repeated 
extraction  hot;  on  treating  the  solution  so  obtained  with  twice  its  quantity  of  ether,  and 
adding  a  sufficient  amount  of  water  to  cause  the  ethereal  layer  to  separate,  the  latter  will 
be  distinctly  blue  and  a  deposit  of  Indigo  will  appear  at  the  junction  of  the  two  layers. 
The  lower  acid  layer  should  be  colorless  and  should  remain  so  when  a  little  hydrochloric 
acid  is  added  to  it. 

(g)  In  compound  shades  Indigo  may  usually  be  detected  by  boiling  several  times  with 
dilute  hydrochloric  acid,  washing  with  water,  and  then  boiling  with  5  per  cent  solution  of 
soda  ash.  This  treatment  will  remove  most  other  dyestuffs.  The  fabric  is  then  dried, 
and  the  tests  which  have  already  been  described  ma^'  be  applied  to  it.  To  detect  small 
amounts  of  Indigo  in  compound  shades,  the  sample  is  treated  as  just  described  with  acid 
and  alkali,  and  then  gently  warmed  with  a  solution  of  sodium  hydrosulphite.  This  is 
then  poured  on  a  piece  of  filter  paper  and  exposed  to  the  air,  when  a  blue  color  wUl  form 
on  the  paper  in  a  few  minutes,  if  Indigo  is  present. 

(h)  Sometimes  Indigo  on  cotton  is  topped  with  Methyl  Violet  or  some  substantive 
reds  for  the  purpose  of  obtaining  brighter  and  redder  shades  Methyl  Violet  may  be 
detected  by  boiling  the  sample  with  alcohol,  allowing  the  solution  to  cool,  and  filtering; 
the  violet  solution  so  obtained  may  be  diluted  with  water  and  a  piece  of  wool  dyed  in  it. 
Substantive  reds  are  indicated  by  boiling  a  piece  of  white  cotton  in  a  slightly  alkaline 
solution  with  a  sample  of  the  material,  when  the  white  cotton  will  be  stained  red. 

11.  Indigo  Derivatives:  Thio-Indigo  Dyes. — There  are  a  number  of 
indipio  derivatives  wliich  have  l^een  prepared  by  s^Tithetic  means  and 
which  are  dyed  in  the  same  general  manner  as  Indigo  itself.  This  entire 
group  may  be  considered  as  Indigoid  dyes,  as  distinguished  from  othej>-^ 
anthraquinone  vat  dyes  of  a  different  chemical  constitution.*  Imio- 
indigo  dyes  are  very  similar  to  Indigo  in  chemical  structure,  having, 
however,  sulphur  in  the  molecule.  The  simplest  one  corresponding  to 
Indigo  is  known  as  Thio-indigo  Red  B,  and  from  this  there  are  a  number 

*  The  indigoid  dyes  air  subliii/ie  when  heated,  giving  colored  vapors.  This  dis- 
tingui.-hes  them  from  the  anthraquinone  and  sulphurized  vat  dyes,  which  do  not  sublime 
(except  Anthraflavone  G).  W^hile  all  of  the  vat  dyes  are  insoluble  in  water  and  the 
common  solvents,  the  indigoids  in  general  are  more  readily  dissolved  than  the  anthra- 
quinone and  sulphurized  vat  dyes;  thus  Indigo  itself  is  soluble  in  boiling  glacial  acetic 
acid,  pyridine,  phenol,  aniline,  benzaldehj'de,  nitrobenzene,  etc. 


THIO-INDIGO    DYES  437 

of  derivatives  which  are  also  vat  dyes.  HcUndonc  Gray  BR  and  HeHn- 
done  Violet  are  chlorine  derivatives;  Thio-intligo  Scarlet  G,  Ciba  Red  G, 
Giba  \'iolet  B,  Giba  Gray  G,  Ciba  Heliotrope,  Giba  Bordeaux  B,*  and 
others  are  bromine  derivatives  of  Thio-indi<!;o.t  The  chemical  formula 
for  Thio-indigo  Red  is 

/GO.  /GO. 

C6H4<        >C  =  G<        >G6H4, 

from  which  its  relation  to  Indigo  may  be  readily  seen.|     These  dyes 

*  The  manufacturers  recommend  the  following  method  of  using  the  Ciba  dyes; 
For  the  purpose  of  dissolving  the  Ciba  dyes,  1  lb.  of  the  dyestuff  is  made  into  a  paste 
with  Ij  lbs.  of  caustic  soda  lye  (66°  Tw.)  and  a  small  quantity  of  hot  water.  Mix  IJ 
lbs.  of  caustic  soda  lye  (66°  Tw.)  with  I5  gallons  of  cold  water,  and  to  this  is  slowly 
added  with  constant  stirring  3j  lbs.  of  hydrosulphite  i)owder.  This  solution  is 
added  to  the  dyestuff  paste  along  with  about  4  gallons  of  hot  water,  and  the  tempera- 
ture is  slowly  raised  to  the  boil.  Ciba  Red  G  should  be  reduced  at  140  to  160°  F.,  and 
Ciba  Scarlet  G  at  100  to  120°  F.  The  addition  of  i  lb.  of  Turkey-red  oil  or  Monopol  oil 
per  100  gallons  of  dye  liquor  is  recommended  in  order  to  obtain  better  penetration. 
The  material  should  be  squeezed  or  wrung  after  dyeing  and  allowed  to  oxidize  in  the  air 
for  fifteen  to  thirty  minutes,  and  then  soaped  at  the  boil  for  one-half  hour  with  2  to  4 
lbs.  of  soap  and  1  to  2  lbs.  of  soda  ash  per  100  gallons  of  liquor.  Ciba  Red  and  Ciba 
Scarlet  may  be  developed  by  passing  through  a  cold  solution  of  bleaching  powder  of  0.7 
to  1.4"  Tw.  The  goods  should  then  be  rinsed  and  treated  with  a  dilute  solution  of 
sodium  bisulphite.  Cops,  tubes,  etc.,  which  have  been  dyed  in  special  apparatus 
should  be  treated  for  one-half  hour  at  175°  F.  with  a  bath  containing  ^  to  3  per  cent 
of  chrome  and  \  to  2  jier  cent  of  acetic  acid,  and  afterwards  thoroughly  rinsed. 

t  The  following  is  a  list  of  the  principal  Thio-indigo  vat  dyes: 

Thio-indigo  Red  BG    1  r  r/  i-  ui      xi  •    •    i- 

5-5  -dichlor-thio-mdigo. 


Helindone  Red  B 

Ciba  Red  B 6-6'-dichlor-thio-indigo. 

Thio-indigo  Red  SB     \  _  _,  ,.  ,  ,      „  „,   ,.      ,,    ,  ,,  .     .    ,. 

^^  ,.    ,        .^    ,  „-r^        >    5-5  -dichlor-0-6  -duuethyl-thio-mdigo. 

Helmdone  Red  SB       J 

Helindone  Fast  Scarlet  R 5-5'-dichlor-6-6'-dieth()xy-thio-indigo. 

Helindone  Gray  BR Dichlor-7-7'-diamino-thio-indigo. 

Helindone  Violet  2B         \  t->-  1 1       i-      xu   1   i-      iu         iu-     •   j- 

„„  .    .    ,.      T,.  ,  ,  „T,       (   Dichlor-dimethvl-dmiethoxy-thio-mdigo. 

1  hio-mdigo  Violet  2B      J 

Ciba  Bordeaux  B 5-5'-dibrom-thio-indigo. 

Helindone  Pink  BN  \  „  ,,,   ,.,  ,•      .1    1  .1  •     •    i- 

„„  .     .    ,.      ^.  .    „-.,        >   6-b -dibrom-dnnethvl-tluo-mdigo. 

1  hio-mdigo  Pmk  BN        J 

Helindone  Orange  D Dibroni-6-6'-dianiiiio-thio-indigo. 

Helindone  Orange  R 


r^...,.      ^  „       ,    6-6'-diethoxy-thio-indigo. 

Ihio-mdigo  Orange  R      J 

Thio-indigo  Scarlet  S        1  n  n>  i-^\  ■       wi-r 

^^  ,.    ,         „      ,  ,  ^,  >   6-6  -dithioxvl-thio-mdigo. 

Helmdone  Scarlet  S  J 

Helindone  Gray  2B  1  -  -r/   i-       ■       ^u-     ■    i- 

rp,  ■     •    ,■      ^        on         (   7-7'-duimmo-thio-mdigo. 

Thio-mdigo  Gray  2B        J 

t  Thio-indigo  is  not  made  directly  from  Indigo,  but  is  synthesized  in  a  manner 
analogous  to  that  of  Indigo  itself.     Anthranilic  acid  is  treated  with  sulphur  to  form  thio- 


438  THE   VAT   DYES 

come  into  the  market  in  the  form  of  pastes  containing  20  per  cent  of  color- 
ing matter,  and  are  dyed  in  vats  prepared  about  in  the  same  manner  as 
for  Indigo.  Thio-indigo  Red  is  also  soluble  in  sodium  sulphide  with  reduc- 
tion, and  hence  may  be  used  in  practically  the  same  manner  as  a  sulphur 
dye,  but  the  color  so  obtained  is  not  as  satisfactory  as  when  produced 
from  the  vat.* 

The  stock  vat  for  Thio-indigo  Red  B  may  be  prepared  as  follows: 
Mix  50  lbs.  of  the  dye  paste  with  25  gallons  of  water;  then  add  31  gallons 
of  hydrosulphite  liquor  (25°  Tw.) ;  heat  to  100°  F.  and  stir  for  one-half 
hour.  Then  add  10  pints  of  caustic  soda  lye  (76°  Tw.)  or  15  lbs.  of  soda 
ash  dissolved  in  12  gallons  of  water.  Stir  until  the  dye  is  reduced,  when 
the  solution  should  be  of  a  yellow  color.  Then  dilute  with  water  to  120 
gallons.  For  a  dyevat  of  500  gallons  use  400  gallons  of  water,  2  gallons 
of  hydrosulphite  liquor  (25°  Tw.)  and  100  gallons  of  the  stock  vat.  Stir 
up  gently  and  allow  to  stand  for  one-half  hour.  When  in  use  as  a  con- 
tinuous vat  successive  quantities  of  the  stock  vat  and  hj^drosulphite  must 
be  added  from  time  to  time.  Thio-indigo  Red  may  also  be  dyed  in  a 
copperas  vat,t  and  may  also  be  used  in  a  mixed  vat  with  Indigo.  Besides 
the  red  and  scarlet  there  are  also  Thio-indigo  Orange  and  Thio-indigo 
Yellow;  these  are  all  dyed  in  the  same  manner,  which  is  also  true  of  the 
other  dyes  of  this  same  class. 

The  colors  obtained  with  Thio-indigo  Red  and  related  dyes  are  very 
fast  to  washing,  light  and  to  chlorine  bleaching.  J  It  is  possible  to  obtain 
a  range  of  colors  from  a  deUcate  pink  to  a  full  bluish  red  with  these  dyes.§ 

salicylic  acid,  and  this  with  monochlor-acetic  acid  is  converted  into  phenylthioglycine- 
ortho-carboxylic  acid,  corresponding  to  the  phenylglycine  of  Indigo.  On  melting  this 
with  caustic  soda  Thio-indigo  is  obtained.  Thio-indigo  Scarlet  is  not  a  direct  Thio- 
indigo  derivative,  but  stands  in  the  same  relation  to  indirubin  as  Thio-indigo  does  to 
Indigo. 

*  This  dye  may  also  be  reduced  with  other  alkaline-reducing  agents  such  as  copperas, 
zinc,  and  caustic  soda,  or  even  glucose  and  caustic  soda. 

t  The  copperas  vat  for  Thio-indigo  Red  may  be  prepared  as  follows:  Stir  50  kilos  of 
the  dyestuff  with  200  liters  of  water;  add  50  kilos  of  copperas  dissolved  in  200  liters  of 
water  and  300  kilos  of  milk-of-lime  (20  per  cent)  and  200  liters  of  water;  make  up  to 
1000  liters.  Stir  until  solution  is  complete.  A  dyevat  of  1000  liters  is  made  by  mixing 
200  liters  of  this  stock  vat  with  800  liters  of  water. 

J  Thio-indigo  Red  has  a  remarkable  resistance  to  oxidizing  agents.  It  may  be  boiled 
in  strong  hypochlorite  solution  without  being  destroyed.  It  is  not  even  destroyed  by 
boiling  chromic  acid  solution. 

§  The  manufacturers  of  the  Helindone  dyes  recommend  the  following  procedure  in 
dyeing:  Hard  water  should  be  corrected  by  adding  3  to  5  oz.  of  soda  ash  and  3  oz.  of 
hydrosulphite  cone,  powder  to  each  100  gallons  of  water;  allow  to  settle  and  use  the  clear 
water.  The  stock  vats  are  prepared  by  making  the  dyestuiT  (1  part)  .into  a  paste  with 
warm  or  cold  water  (20  to  50  parts),  then  adding  2  to  10  parts  of  caustic  soda  lye  (76° 
Tw.)  and  Ho  2  parts  of  Turkone  Oil  N  (a  soluble  sulphonated  oil).  The  1  to  4  parts  of 
hydrosulphite  cone,  powder  are  added  with  constant  stirring.     The  vat  is  best  prepared 


IN  DIG  L/    DERIVATIVES 


439 


12.  Substituted  Indigo  Derivatives. — Besides  the  group  of  Thio-indigo 
dyes  there  are  other  vat  dyes  consisting  of  halogenated  substitution 
products  of  Indigo  itself.  Indigo  R  and  RR,  for  instance,  are  bromine 
derivatives  and  give  redder  shades  than  Indigo.  Indigo  2B,  4B,  and  6B 
are  respectively  di-,  tetra-  and  penta-brom-indigo,  and  range  in  shade 
from  a  bright  blue  to  a  greenish  blue  resembling  Methylene  Blue.*  Indigo 
RB  and  RBN,  Brom-indigo  FB,  Ciba  Blue  B  and  2B,  Midland  Blue  R 
are  also  brom-indigos.  Indigo  T  and  G  are  di-methyl  indigos,  and  give 
greener  shades  than  Indigo  and  are  faster  to  bleaching.  The  famous 
Tyrian  Purple  of  the  ancients  has  been  proved  to  have  been  a  di-brom- 
indigo.  Ciba  Yellow  G  is  also  a  brom  derivative  and  Indigo  Yellow  3G 
Ciba  is  a  derivative  of  dibenzoyi-indigo.  All  of  these  are  vat  dyes  and  are 
dyed  in  the  same  manner  as  the  other  vat  colors  by  the  use  of  a  hydro- 

at  a  temperature  of  100  to  140°  F.  and  it  should  be  ready  for  use  in  from  fifteen  to  thirty- 
minutes.  The  following  table  gives  the  proportions  required  to  reduce  10  parts  of  the 
dyestuff: 


Helindone  Dye  Paste. 


Water. 

Caustic 

Soda 
76°  Tw. 

Turkone 

Oil  N. 

Hydro- 
sulphite 

Cone. 
Powder. 

Temp.°  F. 

40 

7 

4 

60-100 

20 

u 

1 

140 

70 

.  5-6 

3 

70 

20 

2i 

1 

2 

u 

140 

30 

2f 

1 

H 

160 

50 

5J 

2 

2i 

140 

50 

10 

7 

4 

140 

120 

5h 

3 

2 

160 

40 

2f 

1 

U 

120 

40 

7 

4 

100 

50 

21 

1 

n 

104 

50 

8 

2 

140 

50 

4 

2 

140 

50 

2f 

u 

120 

200 

5h 

3 

4 

140 

100 

4 

6 

3 

160 

Temp,  for 

Dyeing 

°  F. 


Yellow  3G,  N.. 

Orange  R 

Orange  G,  NR. 

Scarlet  S 

Fast  Scarlet  R . 

Red  B,  3B 

PinkB 

Pink  AN,  BN.. 

Brown  G 

Brown  3G,  N .  . 
Brown  RR,  5R 
Brown  AN ...  . 

Green  G 

BlueSG,  N..  .  . 
Violet  B,  R. .  .  . 
Violet  BB.  B... 


60-  80 

90-110 

70 

80 

140 

140 

110 

120 

110 

80 

140 

140 

140 

120 
110 


When  dyeing  with  different  dyes  in  the  same  vat,  the  stock  vats  should  be  prepared 
separately  and  mixed  in  the  dyevat.  The  solution  of  the  dj^e  is  added  through  a  fine 
sieve  to  the  dyevat  which  should  have  a  temperature  of  60  to  140  F.  After  dyeing, 
wring  the  yarn  back  into  the  vat,  allow  to  oxidize  in  the  air,  and  soap  at  the  boil. 

*  When  Indigo  is  suspended  in  nitrobenzene  and  treated  with  bromine  at  elevated 
temperatures,  tri-  and  tetra-brom-indigos  are  formed;  the  corresponding  chlorine  com- 
pounds may  be  made  in  a  similar  manner.  All  of  these  compounds  dye  reddish  blue 
colors.  By  suspending  Indigo  in  concentrated  sulphuric  acid  and  treating  with  bromine 
without  heating,  penta-  and  hexa-brom-indigos  are  formed  which  dye  greenish  shades  of 
blue. 


440 


THE   VAT   DYES 


sulphite  vat.     Thoy  arc  principally  used  for  Iho  i^roduotion  of  fast  cotton 
colors. 

Certain  amino  derivatives  of  Indigo  give  brown  vat  dyes;  Ciba  Brown, 
for  instance,  is  a  hrominated  dianiino-indigo,  and  gives  a  reddish  brown 
color  fast  to  light  and  washing,  but  not  fast  to  bleaching.  Naphthalene 
indigos  have  also  been  prepared  from  aljiha  and  beta-naphthylamine; 
they  furnish  green  dyes,  which,  however,  are  of  little  value,  as  they  have 
no  special  fastness.  On  bromination,  however,  the  beta-compound  gives  a 
valuable  dye  (Ciba  Green  G  and  Helindone  Green  G). 


Fig.  225.— Ilydrosulphite  Vat  for  riece-Goocls. 


Indigo  Yellow  3G  is  of  special  interest  in  that  it  may  b(>  dyed  in  com- 
bination with  Indigo  to  give  uniform  green  shades.  Usually  when  the 
indigoid  dyes  arc  applied  in  mixtures  they  give  uneven  colors,  owing  to 
the  difference  in  the  affinities  of  the  dj^es  for  the  fiber  and  the  particular 
conditions  of  temperature  and  amount  of  alkali  that  are  required  for  the 
individual  dyes. 

Indirubin  is  red  indigo  derivative  which  occurs  in  natural  Indigo;  it 
may  also  be  prepared  sj'nthetically  by  condensing  isatin  with  indoxy]. 
It  occurs  in  th-  manufacture  of  synthetic  Indigo  when  air  is  admitted  to 
the  caustic  melt.  In  the  vat  it  is  largely  converted  into  indigo  blue,  but  as 
a  dye  of  itself  very  little  is  fixed  on  the  fiber  and  its  color  is  of  little  value 
as  it  is  not  fast  to  washing.     Certain  halogen  derivatives  of  indirubin. 


ANTHRAQUINONE   DVE8  441 

however,  are  useful  vat  dyes,  such  as  Ciha  Heliotrope  B,  which  is  a  tetra- 
brominated  indirubin. 

There  are  also  vat  dyes  of  Indigo  derivatives  which  are  obtained  l^y  the 
condensation  of  isatin  with  naphthol,  anthranol,  or  similar  compounds. 
Alizarine  Indigo  3R  is  obtained  from  dibrom-isatin  condensed  with  alpha- 
naphthol,  while  Helindone  Blue  3GN  and  Alizarine  Indigo  G  arc  anthranol 
derivatives  with  isatin. 

13.  Anthraquinone  Vat  Dyes. — These  dyes  are  derived  from  amino- 
anthraquinone  compounds,*  and  include  the  Indanthrene,  Algol,  Cibanone, 
and  some  of  the  Helindone  dyes.  Indanthrene  itself  (which  is  also  known 
as  Indanthrene  Blue  RS)  may  be  considered  as  an  azine  condensation 
product  of  di-anlhraquinone,  and  has  the  fonnula: 

/CO.  .NH.  .CO. 

CGHi<        >CoHo<         >CgHo<        >CcH4. 

^CO^  ^nh/  ^CO^ 

This  will  dye  a  blue  color  on  cotton  from  a  hydrosulphite  vat,  giving 
shades  very  fast  to  light  and  washing  but  not  to  hypochlorite  bleaching. 
By  forming  halogen  substitution  products,  however,  dyes  fast  to  chlorine 
are  obtained.  Indanthrene  Blue  RC  is  the  mono-brom  derivative; 
Indanthrene  Blue  GC  and  GCD  are  respectively  the  di-brom  and  the  di- 
chlor-dei'ivativcs.  Indanthrene  Blue  CE  and  Algol  Blue  CF  are  similar 
products.  Dihydroxy-indanthrenes  are  also  known  including  Algol  Blue 
3B,  Indanthrene  Blue  3G  and  2GS;  these  give  bright  greenish  shades  of 
blue. 

Other  related  dyes  of  this  same  grouj)  are  as  follows : 

Algol  Blue  3G  Algol  Brilliant  Orange  FR  Algol  Gray  B 

Algol  Blue  K  Algol  Brilliant  Red  2B  Algol  Green  B 

Algol  Blue  3R  Algol  Brilliant  Violet  2B  Algol  Olive  R 

Algol  Bordeaux  3B  Algol  Brilliant  "\'iolet  R  Algol  Orange  R 

*  The  discovery  of  the  anthraquinone  vat  dyes  is  the  latest  important  dovelopment 
in  tinctorial  chemistry.  Anthraquinone  is  a  cheap  raw  material  and  is  caiwble  of  a  large 
number  and  variety  of  reactions,  consequently  there  has  been  great  activity  in  the  prep- 
aration of  vat  dj'es  derived  from  this  product.  IManj-  of  tliese  compounds,  however, 
are  useless  as  dyes  as  they  possess  no  affinity  for  the  fiber.  These  anthraquinone  dyes 
are  characterized  by  a  high  molecular  weight  and  a  very  complex  chemical  constitution, 
and  apparently  this  goes  hand  in  hand  with  their  great  fastness.  Some  are  also  peculiar 
in  that  they  contain  no  nitrogen  in  the  molecule;  such  a  dye,  for  instance  as  Indanthrene 
Violet  R  has  the  empirical  formula  CsiHisOa,  which  approaches  that  of  a  hydrocarbon. 
The  anthraquinone  vat  dyes  usually  require  a  more  strongly  alkaline  vat  than  the  indi- 
goid  dyes,  and  consequently  are  applied  almost  exclusively  to  cotton  dyeing.  They 
may  be  used  for  wool  if  the  fiber  is  first  treated  with  formaldehyde  to  lessen  its  sensi- 
tiveness to  alkalies.  A  new  class  of  anthraquinone  vat  dyes  has  been  obtained  by  the 
action  of  diazo-anthraquinone  on  certain  aromatic  amines  after  the  manner  of  prejiaring 
the  azo  dyes, 


442 


THE   VAT   DYES 


Algol  Pink  R 
Algol  Red  B 
Algol  Red  5G 
Algol  Red  R 
Algol  Scarlet  G 
Algol  Violet  B 
Algol  Yellow  30 
Algol  Yellow  R 
Algol  Yellow  WG 
Anthraflavone  G 
Cibanone  Black  B 
Cibanone  Blue  3G 


Cibanone  Green  B 
Cibanone  Orange  R 
Cibanone  Yellow  R 
Helindone  Yellow  3GN 
Indanthrene  Black  B 
Indanthrene  Blue  R  * 
Indanthrene  Bordeaux  B 
Indanthrene  Dark  Blue  BO 
Indanthrene  Golden  Orange  G 
Indanthrene  Golden  Orange  R 
Indanthrene  Gray  B 
Indanthrene  Green  Bj 


Indanthrene  Maroon 
Indanthrene  Olive  Gt 
Indanthrene  Red  BN 
Indanthrene  Red  G 
Indanthrene  Scarlet  G 
Indanthrene  Violet  R 
Indanthrene  Violet  RN 
Indanthrene  Violet  RT 
Indanthrene  Yellow 
Leucole  Brown  B 
Leucole  Dark  Green  B 


It  will  be  noticed  that  these  vat  dyes  now  cover  a  wide  range  of  colors. 
They  are  very  fast  to  light  and  washing  and  many  of  them  are  also  very 


Fig.  226. — Indigo  Dyeing  Machine  for  Slubbing.     (Obermaier's  System.) 

fast  to  bleaching,  though  this  quality  varies  with  the  individual  dye,  and 
in  order  to  obtain  bleaching-fast  shades  a  proper  selection  of  dyes  must  be 
made  for  the  purpose. 

These  vat  dyes  are  brought  into  solution  in  caustic  soda  by  reduction 
with  sodium  hydrosulphite.     In  a  vat  thus  prepared,  however,  they  act 

*  Indanthrene  Blue  R  is  one  of  the  oldest  and  is  still  one  of  the  most  important  of  the 
vat  dyes.  It  is  prepared  by  heating  beta-aminoanthraquinone  with  caustic  alkali  and 
potassium  nitrate.     It  gives  a  dark  blue  vat  which  dyes  bright  blue  colors. 

t  Indanthrene  Green  B  is  an  interesting  product;  it  is  a  nitration  product  prepared 
from  Indanthrene  Blue  BO.  When  dyed  on  cotton  and  treated  with  oxidizing  agents 
a  fast  black  color  is  obtained  (Indanthrene  Black  B). 

X  Indanthrene  Olive  G,  together  with  the  Cibanone  dj'es,  are  obtained  from  anthra- 
cene by  heating  with  sulphur,  after  the  manner  of  making  sulphur  dyes.  These  colors 
are  fast  to  light  and  washing  but  not  to  bleaching. 


DYEING  VAT   COLORS  443 

very  much  after  the  manner  of  substantive  dyes  on  cotton,  some  of  them 
being  dyed  ahnost  at  the  boil,  the  dyeing  and  development  of  the  color 
taking  place  almost  simultaneously,  and  the  dyebath  becoming  practically 
exhausted.  Some  of  these  dyes,  however,  must  be  appUed  at  lower  tem- 
peratures, and  require  subsequent  oxidation  in  order  to  develop  the  color. 
The  vat  dyes  are  brought  into  trade  in  the  form  of  pastes  containing 
from  8|  to  20  per  cent  of  coloring  matter.  For  the  production  of  heavy 
shades  large  proportions  of  the  pastes  must  be  taken. 

For  the  application  of  the  vat  dyes  the  Badische  Co.  recommend  the 
following  procedure  for  cotton  yarn :  The  yarn  is  first  boiled  out  with  soda 
ash  with  or  without  the  addition  of  Turkey-red  oil.  For  dyeing  100  lbs. 
of  yarn  use  a  dye-vessel  with  225  gallons  of  water;  add  4^  gallons  of  caustic 
soda  lye  (53°  Tw.)  and  heat  to  140°  F.  (when  using  Indanthrene  Blae  GC, 
GCD  and  RC  heat  only  to  120°  F.),  skim  off  any  precipitate,  add  the 
necessary  quantity  of  hydrosulphite  (previously  dissolved  in  ten  times  its 
weight  of  cold  water),  and  finally  add  the  dyestuff  as  a  thin  paste  made  up 
with  ten  times  its  weight  of  hot  water.  Allow  the  vat  to  rest  until  the  d3'e 
has  been  completely  dissolved.  The  yarn  should  be  immersed  in  the  liquor 
on  bent  iron  sticks.  The  vat  should  be  kept  at  140°  F.  or  120°  F.  as  the 
case  may  be.  In  dyeing  light  shades,  however,  105°  F.  is  all  that  is  neces- 
sary. After  dyeing  heavy  shades  the  yarn  should  be  drained  and  then 
rinsed  in  a  bath  containing  2  ozs.  of  hydrosulpliite  cone,  per  100  gallons  of 
water.  When  preparing  a  fresh  bath  2  gallons  of  caustic  soda  lye  (53°  Tw.) 
should  be  added  per  100  gallons  of  water,  and  the  amount  of  hydrosulphite 
cone,  should  be  about  one-fourth  that  of  the  dj^estuff  used;  in  no  case, 
however,  should  it  be  less  than  1  lb.  nor  more  than  4  lbs.  per  100  gallons. 

A  hydrosulphite  solution  that  will  keep  for  some  time  may  be  prepared 
by  slowly  adding  10  lbs.  of  hydrosulphite  cone,  (anlwdrous  sodium  hydro- 
sulphite) to  9  gallons  of  cold  water,  and  when  dissolved  add  4  pints  of 
caustic  soda  lye  (53°  Tw.).  Of  the  ordinary  paste  dyes,  from  |  to  50  per 
cent  may  be  used  (calculated  on  the  weight  of  the  cotton) ;  but  when 
employing  the  dry  powder  brands,  from  10  to  12|  per  cent  will  give  heavy 
shades.  The  dyebath  is  usually  not  exhausted  when  dyeing  heavy  colors, 
and  it  may  be  used  as  a  continuous  vat,  only  one-sixth  to  one-fifth  of  the 
caustic  soda  originally  added  should  be  used,  and  afterwards  the  necessaiy 
amounts  of  dyestuff s  and  hydrosulphite. 

After  dyeing  the  colors  may  be  brightened  by  soaping  at  140°  F.  with 
3  to  5  lbs.  of  soap  per  100  gallons. 

Cotton  piece-goods  should  be  dyed  in  an  under-water  jigger,*  and 

*  Piece-goods  may  also  be  dyed  with  the  vat  dyes  in  the  dipping  vat.  For  this 
purpose  the  goods  are  well  boiled,  dried,  and  stretched  on  the  dipping  frame  and  im- 
mersed in  the  well-stirred  vat  at  160  to  180°  F.  for  ten  to  twenty  minutes.  The  frame 
is  then  raised  and  placed  in  water  without  delay.     After  the  goods  have  been  slightly 


444 


THE   VAT   DYES 


ufter  dyeing  rinse  in  a  bath  containing  2h  ozs.  of  hydrosiilphite  per  100 
gallons;  then  wash  free  from  soda,  and  sour  with  1  to  2  joints  of  sulphuric 
acid  per  100  gallons,  rinse,  and  soap  at  the  boil.  In  order  to  oxidize  the 
dyestuff  more  rapidly  after  dyeing,  5  to  8  ozs.  of  sodium  bichromate  should 
be  added  per  100  gallons  of  the  souring  licjuor.  This  aids  in  producing 
more  uniform  shades  and  also  increases  the  fastness  to  soaping.  Piece- 
goods  may  also  be  dyed  by  padding.* 

14.  The  Carbazol  Vat  Dyes. — Certain  vat  dyes  of  great  importance  are 
obtained  from  carbazol  f  by  treatment  with  sodium  polysulphide,  somewhat 
after  the  manner  of  making  the  sulphur  dyes.  These  dyes  include  the 
Hydron  Blues  and  Indocarbon  S.  The  are  applied  in  hydrosulphite  vats 
in  the  usual  manner  and  give  colors  wliich  are  very  fast  to  light,  washing 
and  bleaching. 

For  the  dyeing  of  Hydron  Blues  on  cotton  yarn  the  following  method 
is  recommended  by  the  manufacturer:  t 


Dj'estuff  (20  per  cent  paste) 

Hydrosulphite  cone,  powder 

Caustic  soda  lye  (75°  Tw.) 

Proportion  of  yarn  to  liquor,  1  :  2:i 


starting  Ba!h, 
Per  Cent. 


2  to  30 
2  to  15 
2  to  15 


Additions, 
Per  Cent. 


2  to  24 
1  to  12 
1  to    8 


Heat  the  bath  to  al)out  120  to  140°  F.,  add  the  caustic  soda  and  the 
dyestuff,  gradually  stir  in  the  hydrosulj^hite  (either  in  powder  form,  or 
better  dissolved  in  cokl  water)  and  stir  well  until  the  dye  has  been  com- 
pletely reduced.  Dye  for  one-half  hour  at  120  to  140°  F.,  preferably  on 
bent  sticks,  squeeze  or  wring,  oxitlize  in  the  air,  and  rinse.  The  yarn  should 
be  finally  soured  with  sulphuric  acid  solution,  thoroughly  washed  and 

rinsed  they  are  removed  from  the  frame  and  soured  with  ^  gallon  sulphuric  acid  per  100 
g.illons  of  water,  rinsed  well  and  soaped  at  tlie  boil.  To  produce  deep  shades  several 
dips  should  be  given. 

*  The  padding  liquor  may  be  prepared  as  follows:  1  to  20  lbs.  of  the  dyestuff  paste  are 
cu'cfully  mi.xed  with  122  to  15  lbs.  or  gum  thickener  (1  :  1)  and  made  up  to  10  gallons 
with  water.  Filter  through  cotton  cloth;  pad  and  develop  for  one-half  to  three-quarters 
of  an  hour  in  an  ordinary  jigger  nearly  filled  with  water,  containing  2^  gallons  caustic  soda 
lye  (53"  Tw.)  and  Ij  to  I5  lbs.  of  hydrosulphite  powder  per  100  gallons  of  water.  The 
goods  are  finally  given  two  ends  in  water  containing  .3  ozs.  hydrosulphite  powder  per 
100  gallons,  rinsed,  soured,  rinsed  again,  and  soaped  at  the  boil. 

t  Carbazol  is  a  product  occurring  in  coal-t;ir  in  association  with  anthracene,  and  is 
obtained  in  the  purification  of  the  latter. 

X  Hydron  Blue  is  often  dyed  in  a  vat  made  up  with  sodium  suli)hide,  caustic  soda, 
and  hydrosulphite,  better  penetration  being  obtained  by  the  use  of  the  sodium  sulphide. 
This  dye  may  also  be  dyed  like  a  sulphur  color  by  dissolving  in  sodium  sulphide  alone, 
but  the  colors  obtained  this  way  are  not  so  good. 


EXPERIMENTAL  STUDIES 


445 


soaped.  Piece-goods  may  be  dyed  on  the  jigger,  which  should  be  pro- 
vided with  squeezing  rollers;  dyeing  for  one-half  to  three-quarters  of  an 
hour  at  140°  ¥.,  squeeze,  pass  through  the  air  to  oxidize,  rinse  first  in 
acidulated  water  and  then  in  pure  water. 

15.  Experimental.  Exp.  150.  Preparation  of  Indigo  Solution.— Mix  75  grams  of 
Indigo  paste  (20  per  cent)  with  40  ec.  of  hot  water,  and  90  cc.  of  caustic  soda  *  solution 
( 12°  Tw.)  and  50  grams  of  hydrosulphite  powder  (Blankit  T)  dissolved  in  200  cc.  of 
water.  Stir  gently  and  keep  the  temperature  at  about  110°  F.  In  a  short  time  the 
liquor  should  be  of  a  clear  amber-yellow  color  with  a  film  of  blue  on  the  top.  Tlio  liquid 
now  contains  indigo-white  and  serves  as  a  stock  Indigo  solution  for  the  preparation  of 
the  dvevat.  The  hydrosulphite  powder  (Blankit  T)  is  a  anhydi'ous  compound 
of  sodium  hydrosulphite  and  is  a  fairly  stable  body  compared  with  most  hydrosulijliite 


Fig.  227. — Dyeing  Machine  for  Slubbing.     (Simonis.) 


derivatives.  It  is  a  strong  rsducing  agent  and  converts  the  indigo-blue  into  indigo- 
white.  In  place  of  this  prepai'sd  form  of  hydrosulphite  the  solution  of  sodium  hydro- 
sulphite itself  may  be  used,  in  w'lich  case  it  may  be  prepared  as  follows:  130  grams  of 
zinc  dust  are  made  into  a  paste  with  55  cc.  of  water,  wliich  is  then  mixed  with  1000  cc. 
of  sodium  bisulphite  solution  of  72°  Tw.  As  the  mixtin-e  is  liable  to  become  heated,  the 
temperature  should  be  kept  below  100°  F.  by  the  addition  of  ice  or  cold  water;  when 
the  chemical  action  has  ceased,  dilute  to  2  liters  and  allow  to  stand  for  one  hour.  Then 
stir  in  200  cc.  of  a  20  per  cent  milk-of-lime  solution,  cold,  and  allow  to  stand  for  two 
hours.  This  causes  the  precipitation  of  all  the  zinc  as  zinc  hydrate.  The  liquor  is 
then  strained  to  free  it  from  sediment  and  preserved  in  a  closed  bottle.  The  hydro- 
sulphite solution  thus  prepared,  if  kept  in  a  cool  place,  will  last  for  several  weeks,  and 
its  keeping  quality  will   be   enhanced  by  the   addition   of  a   small   quantity  of  caustic 


*  The  caustic  soda  may  be  replaced  by  140  cc.  of  milk-of-lime  (20  per  cent").  The 
latter,  however,  is  objectionable  on  account  of  the  sediment  in  the  vat.  Where  lime  is 
used  in  the  vat  it  is  also  necessary  to  acidify  the  dj'ed  material  to  remove  traces  of  lime. 


446 


THE  VAT   DYES 


soda  solution.     When  zinc  dust    reacts  with  a  solution  of  sodium  bisulphite    the  fol- 
lowing chemical  change  takes  place: 


Zn 

+     3  NaHSOs 

=     NaHSOj     + 

Zn(XaSO.O 

+      H2O. 

Zinc 

Sodium  bisulphite 

Sodium  hydro- 
sulphite 

Zinc-sodium 
bisulphite 

Water 

Sodium  hydrosulphite  is  a  strong  reducing  agent,  being  itself  oxidized  finallj'  to 
sodium  bisulphate,  NaHSOi.  Its  use  forms  a  verj^  convenient  means  for  the  prepara- 
tion of  dyeing  solutions  of  Indigo  as  well  as  the  other  vat  dyes.  The  sodium  hydrosul- 
phite solution  is  usually  prepared  by  the  dyer  as  a  stock  solution,  and  used  as  occasion 
requires  for  the  reduction  of  the  dyestuff  to  be  added  to  the  vat. 


Fig.  22s. — Indigo  Dyeing  Machine.     (James  Hunter  Machine  Co.) 


Exp.  151.  Dyeing  Indigo  with  Hydrosulphite  Vat. — Prepare  the  dyevat  as  follows: 
to  one  liter  of  water  (120°  F.)  add  2  grams  of  hydrosulphite  powder  (or  10  cc.  of  the  above 
prepared  hydrosulphite  liquor);  0.5  cc.  of  ammonia  water,  and  4  cc.  of  glue  solution 
(1 :10) ;  allow  to  stand  for  fifteen  minutes,  then  run  in  100  cc.  of  the  stock  Indigo  solution 
by  means  of  a  long-tubed  funnel.  Stir  gently  and  allow  to  stand  for  thirty  minutes 
When  the  liquor  is  clear  and  of  an  amber-yellow  color  it  is  ready  for  use.  Take  a  test 
skein  of  cotton  yarn  which  has  been  boiled  out  and  squeezed  (but  not  dried)  and  pass  it 
through  this  indigo  vat  without  heating.  Take  care  to  manipulate  the  dyeing  so  as  to 
disturb  the  liquor  as  little  as  possible,  as  much  exposure  to  the  air  will  cause  undue 
oxidation  and  considerable  Indigo  will  be  precipitated  in  the  vat.  When  the  skein 
has  become  thoroughly  and  evenly  saturated  with  the  hquor,  squeeze  it  out  well,  and 


EXPERIMENTAL  STUDIES  447 

then  expose  the  skein  to  the  air  for  five  to  ten  minutes.  When  the  skein  first  comes 
from  the  vat  it  should  be  of  a  yellowish  green  color;  on  exposure  to  the  air  it  soon  turns 
blue.  The  dyed  skein  is  then  washed  well  in  water  and  afterwards  in  a  warm  soap 
solution  in  order  to  remove  aU  alkali  and  unfixed  dyestuff.  Dye  a  second  test  skein  of 
cotton  yarn  in  a  similar  manner,  but  after  oxidizing  in  the  air  give  it  a  second  passage 
through  the  indigo  vat  and  oxidize  again,  after  which  wash  and  soap.  This  will  repre- 
sent the  color  obtained  by  two  dips.  In  the  same  manner  dye  a  third  skein,  giving  it 
four  dips.  Also  dye  skeins  of  woolen  yarn  in  the  same  manner,  giving  one  dip,  two  dips 
and  four  dips.  For  the  woolen  yarn  use  a  first  wash  water  acidulated  with  a  little 
sulphuric  acid  in  order  to  neutralize  the  alkali;  then  wash  well  again  in  plain  water  and 
finally  soap.  If  the  dyevat  turns  bluish  owing  to  oxidation  a  fresh  quantity  of  hydro- 
sulphite  must  be  added,  the  liquor  stirred  gently  and  allowed  to  stand  for  fifteen  minutes. 
When  the  vat  is  maintained  for  some  time  a  little  ammonia  and  glue  solution  are  occa- 
sionally added.  To  maintain  the  proper  dyeing  strength  of  the  vat  fresh  additions  of  the 
stock  solution  of  Indigo  are  made  from  time  to  time  as  needed.  If  too  much  hydrosul- 
phite  is  present  in  the  vat  the  color  will  not  be  well  taken  up  and  the  blue  will  not  develop 
quickly  on  exposure  to  the  air. 

The  hydrosulphite  vat  for  Indigo  is  the  simplest  and  the  most  popular  method  of 
applying  this  dyestuff  at  the  present  time.  Other  forms  of  vats,  depending  on  the 
nature  of  the  reducing  agent,  have  been  used.  The  fermentation  vat  is  the  oldest  form 
of  Indigo  dyeing  and  is  still  used  to  a  considerable  extent  in  wool  dyeing.  Its  operation 
depends  on  the  reducing  action  of  certain  ferments,  and  it  is  prepared  with 
bran,  woad,  and  madder.  The  woad  is  supposed  to  furnish  the  particular  ferment 
while  the  bran  and  madder  serve  as  nourishment  for  the  growth  of  the  ferment.  The 
alkali  employed  is  Ume,  which  serves  the  double  purpose  of  neutralizing  the  acid  lib- 
erated in  the  fermentation  and  providing  the  alkali  necessary  for  the  solution  of  the 
reduced  Indigo.  The  fermentation  vat  is  difficult  to  prepare  and  also  difficult  to  main- 
tain in  proper  working  condition.  The  warm  fermentation  vat  is  employed  where  the 
work  is  regularly  continuous;  where  rapid  dyeing  is  desired  or  where  the  dyeing  is 
irregularly  carried  on,  the  hydrosulphite  vat  is  more  advantageous.  The  cold  fermen- 
tation vat  is  largely  used  in  Oriental  countries,  where  time  is  not  an  essential  factor  in 
the  operation.  The  copperas  vat  employs  ferrous  sulphate  as  the  reducing  agent  and 
lime  as  the  alkali.*  It  is  a  cumbersome  and  imsatisfactory  method  and  is  not  used  at 
present.  The  zinc  vat  uses  zinc  dust  for  the  reducing  agent  and  either  lime  or  caustic 
soda  as  the  alkali.     It  is  quite  an  efficient  form  of  vat  and  is  still  employed  considerably 

*  A  copperas  vat  of  medium  strength  may  be  prepared  as  follows: 

20  lbs.  Indigo  paste. 
25  lbs.  quick-lime. 
20  lbs.  copperas. 

Make  up  to  40  gallons  and  allow  to  stand  for  four  to  six  hours  with  occasional  stirring. 
When  the  color  of  the  liquor  is  yellow  it  is  ready  for  use.  This  forms  the  stock  vat  and 
the  liquor  is  poured  off  from  the  sediment  into  the  dyeing  vat  as  needed.  As  long  as  the 
sediment  is  yellow  in  color  the  vat  is  in  proper  condition,  and  if  the  liquor  becomes 
blue  during  working,  on  stirring  up  and  settling  it  will  turn  yellow  again.  When  the 
reducing  power  of  the  sediment  becomes  exhausted  more  copperas  and  lime  must  be 
added.  In  the  copperas  vat  a  considerable  portion  of  the  Indigo  is  destroyed  by  over- 
reduction or  by  the  formation  of  a  useless  iron  compound.  This  loss  generallj'  amounts 
to  25  per  cent,  though  this  may  be  increased  if  the  stock-vat  is  kept  too  long.  The 
advantage  the  copperas  vat  possessed  over  the  old  form  of  fermentation  vat  was  that  it 
was  comparatively  easy  to  set  and  did  not  easily  get  out  of  order. 


448  THE   VAT   DYES 

in  cotton  dyeing.*  All  of  these  vats,  however,  contain  a  large  amount  of  sediment, 
and  care  must  be  taken  in  dyeing  not  to  disturb  this  sediment  or  it  will  get  into  the 
goods  being  dyed.  There  is  also  considerable  loss  of  Indif.>()  in  these  vats,  whereas  in 
the  hydrosulphite  vat  there  is  no  sediment,  and  the  loss  of  Indigo  is  exceedingly  small. 

Test  the  fastness  of  the  Indigo  dyeings  to  light,  washing,  fulling,  acids,  and  chloring 
(on  cotton). 

Exp.  152.  Reactions  of  Indigo. — (1)  Take  about  1  cc.  of  Indigo  paste  in  a  small 
test  tube,  and  1  cc.  caustic  soda  solution,  then  fill  the  tube  with  hydrosulphite  solution, 
stop  with  a  cork  and  shake  well  until  the  Indigo  is  all  reduced  and  a  clear  yellow  solu- 
tion results.     The  following  reaction  has  taken  place: 

/COx  /COv 

CeH/  >C=C<  ^CeHi+NaHSOs  +  IIoO 

\nh/  \nh/ 

Indigotine 


/C(OH)^  y^CiOUK 

=  C6H/  yC—Cf  >C6H4+NaHS03 

\   NH   /  \   NH   / 


Indigo-white 

Now  add  a  few  drops  of  hydrochloric  acid  to  the  solution  of  indigo- white,  taking  care 
to  avoid  the  introduction  of  any  air,  which  will  cause  the  formation  of  indigo  blue.  As 
the  solution  becomes  neutralized  a  white  flaky  precipitate  of  indigo-white  separates  out. 

(2)  Place  a  drop  of  Indigo  paste  in  a  test  tube,  shake  with  a  little  water,  and  then 
add  several  drops  of  a  solution  of  potassium  permanganate.  The  Indigo  will  be  decol- 
orized due  to  the  strong  oxidizing  action  of  the  potassium  permanganate.  On  this  is 
based  the  method  of  analysis  of  Indigo  samples. 

(3)  Repeat  this  test,  using  a  few  drops  of  potassium  bichromate  solution  instead  of 
permanganate.  The  Indigo  will  also  be  decolorized.  This  reaction  is  used  very  largely 
in  the  discharge  of  Indigo  in  calico  printing. 

(4)  Repeat  the  test,  using  instead  of  potassiiuii  bichromate  a  solution  of  hydrogen 
peroxide.     The  same  effect  will  be  obtained. 

(5)  Repeat  the  test,  using  an  acid  solution  of  stannous  chloride  and  apply  heat.  The 
color  of  the  Indigo  will  be  rapidly  discharged. 

(6)  Place  a  small  quantity  of  Indigo  powder  in  a  test  tube;  add  a  few  cc.  of  clear 
aniline  oil  and  warm  carefully  (vapors  of  aniline  are  inflammable) .  The  Indigo  will  pass 
into  solution  giving  a  bluish  or  greenish  blue  liquid  (greenish  on  account  of  the  yellowish 
color  of  the  aniline  oil) . 

*  The  zinc-lime  vat  may  be  prepared  in  the  following  manner: 

20  lbs.  of  Indigo  paste. 

2§  lbs.  of  zinc  dust. 

8  to  10  lbs.  of  quicklime  previously  slaked  to  a  uniform  paste. 

16  gallons  of  hot  water. 

This  mixture  is  stirred  occasionally  during  three  to  five  hours,  when  it  should  bo  yellow 
in  color  and  ready  for  use.  This  forms  the  stock  solution.  The  dyevat  (for  200 
gallons)  is  set  with  ^  lb.  of  zinc  dust  and  2  lbs.  of  lime  (slaked),  stirred  up  and  allowed  to 
stand  for  some  hours.  The  stock  liquor  is  then  added.  This  vat  is  in  good  working 
condition  when  its  sediment  is  yellow  in  color.  It  is  freshened  up  by  additions  of 
I  to  1  lb.  of  zinc  dust  and  1  to  2  lbs.  of  lime.  In  the  zinc  vat  the  loss  of  dyestufF  is  less 
than  10  per  cent,  in  which  respect  it  has  an  advantage  over  the  copperas  vat.  The 
sediment  is  also  not  so  large,  hence  it  may  be  maintained  in  use  for  a  much  longer  i)eriod 
of  time. 


EXPERIMENTAL  STUDIES  449 

(7)  Repeat  this  test,  using  a  few  cc.  of  glacial  acetic  acid,  which  will  also  be  found  to 
dissolve  the  Indigo.  On  adding  water  the  Indigo  will  be  reprecipitated.  Indigo  is  also 
soluble  in  nitrobenzene,  but  not  in  alcohol  or  ether. 

(8)  To  a  small  quantity  of  Indigo  powder  in  a  test  tube  add  a  few  cc .  of  concentrated 
sulphuric  acid  and  warm  gently.  A  deep  blue  solution  results;  dilute  with  a  large 
amount  of  water,  bring  to  a  boil  and  dye  a  skein  of  wool  therein.  The  Indigo  has  been 
converted  into  Indigo  Extract,  an  acid  dye. 

(9)  To  a  small  quantity  of  Indigo  powder  in  a  test  tube  add  a  few  cc.  of  concen- 
trated nitric  acid.  The  Indigo  is  decolorized,  and  becomes  yellow.  This  is  the  basis 
of  the  nitric  acid  test  for  Indigo. 

(10)  To  a  small  quantity  of  Indigo  paste  in  a  test  tube  add  a  few  cc.  of  a  solution  of 
chloride  of  lime.     The  Indigo  will  soon  be  decolorized. 

Exp.  153.  Indigo  Extract. — (1)  Starting  with  100  grams  of  powdered  Indigo,  prepare 
a  sample  of  Saxony  Blue  as  described  on  page  431.  Using  a  small  quantity  of  this  as  a 
dyestuff,  dye  several  samples  of  loose  wool,  3'arn,  and  cloth.  The  dyebath  will  not 
require  the  addition  of  any  acid,  as  the  extract  itself  contains  considerable  excess  of  sul- 
phuric acid;  add,  however,  20  per  cent  of  glaubersalt  to  the  bath,  and  dye  in  the  usual 
manner  for  acid  colors. 

(2)  Take  about  one-fifth  of  the  Saxony  Blue  paste,  dilute  with  twice  its  volume  of 
water,  and  pour  into  a  saturated  solution  of  salt;  filter  ofT  the  precipitate  formed,  and 
preserve  as  a  sample  of  acid  indigo  extract.  Dye  several  samples  of  wool  with  a  small 
amount  of  this  extract,  in  the  manner  above  described. 

(3)  Take  another  fifth  part  of  the  Saxony  Blue  paste,  dilute  with  twice  its  volume 
of  water,  and  pour  into  a  saturated  solution  of  salt;  filter  off  the  precipitated  coloring 
matter.  Dissolve  in  a  small  amount  of  water;  add  a  solution  of  sodium  carbonate  until 
effervescence  ceases;  then  pour  into  a  saturated  solution  of  salt  again,  and  filter.  Test 
the  precipitate  for  acid,  and  if  not  perfectly  neutral  repeat  the  operations  again.  Pre- 
serve this  sample  as  sweet  extract  of  indigo ;  and  dye  several  samples  of  wool  therewith, 
employing  the  usual  acid  dyebath  of  4  per  cent  sulphuric  acid  and  20  per  cent  glauber- 
salt. Compare  with  the  several  samples  for  purity  and  clearness  of  tone.  Also  com- 
pare these  colors  obtained  with  Indigo  Extract  with  those  prepared  from  vat  Indigo. 
It  will  be  found  that  the  extract  gives  much  brighter  shades,  and  that  the  tone  is  some- 
what different.  Make  tests  on  samples  of  the  two  colors  for  light  (thirty  days'  exposure) ; 
washing,  fulling,  acids,  and  alkalies.  It  will  be  found  that  vat  dyed  Indigo  is  a  great  deal 
faster  than  the  extract. 

Exp.  154.  Use  of  Thio-Indigo  Red. — Stir  50  grams  of  Thio-indigo  Red  B  paste  with 
200  cc.  of  water,  add  10  cc.  of  caustic  soda  solution  of  76°  Tw.,  then  gradually  stir  in  10 
grams  hydrosulphite  powder  (Blankit  T).  Heat  to  120°  F.  and  allow  to  stand  for  two 
hours,  or  until  the  reduction  is  complete  and  the  solution  is  of  a  yellow  color.  Dilute 
to  one  liter  and  preserve  as  a  stock  solution  for  dyeing.  For  the  dyevat  take  400  cc.  of 
water  of  a  temperature  of  about  100°  F.,  add  20  grams  of  salt,  a  small  quantity  (0.1 
gram)  of  hydrosulphite  powder  and  a  few  drops  of  caustic  soda  solution  (76°  Tw.). 
Stir  well,  allow  to  stand  for  fifteen  minutes  and  then  add  100  cc.  of  the  stock  dye  solution. 
Stir  gently  and  allow  to  stand  for  one  hour,  when  the  vat  should  be  of  a  clear  yellow  color 
and  ready  for  dyeing.  Steep  a  test  skein  of  cotton  yarn  in  this  vat  for  fifteen  minutes, 
then  squeeze  and  oxidize  in  the  air  for  thirty  minutes.  Dye  another  skein  in  the  same 
manner,  giving  it  three  dips,  and  a  third  skein,  giving  it  five  dips.  The  addition  of  salt 
is  for  the  purpose  of  causing  a  more  rapid  fixation  and  better  exhaustion  of  the  dyestuff. 
The  bath  may  be  strengthened  by  further  additions  of  the  stock  solution.  If  the  bath 
becomes  red  and  loses  its  clear  yellow  color  a  little  more  hydrosulphite  powder  should 
be  added,  and  the  liquor  stirred  gently  and  allowed  to  stand  for  fifteen  to  thirty 
minutes  to  allow  it  to  become  thoroughly  reduced  again. 


450  THE   VAT   DYES 

Piepare  a  vat  with  Thio-indigo  Scarlet  R  in  tlic  same  manner  as  above  and  make 
d\-eings  with  one  dip,  three  dips  and  five  dips. 

When  the  dyeings  have  been  exposed  to  the  air  sufficiently  to  become  thoroughly 
oxidized,  they  should  be  well  washed  in  water  and  then  in  warm  soap  solution  to  rcuio\  e 
all  unfixed  dj-cstuff  and  chemicals. 

Test  the  fastness  of  the  two  dyestuffs  to  light,  washing,  and  bleaching. 

Exp.  155.  Use  of  Indanthrene  Blue. — Prepare  a  dychath  with  400  cc.  of  water,  8  cc. 
of  caustic  soda  solution  (53°  Tw.),  and  8  grams  of  Blankit  T.  Heat  to  120°  F.,  and  then 
stir  in  2  grams  (20  per  cent)  of  Indanthrene  Blue  GCD.  When  the  liquor  is  clear  and 
shows  no  undissolved  particles  (test  by  dropping  on  a  piece  of  filter  paper),  the  bath  is 
ready  for  dyeing.  Dye  a  test  skein  of  cotton  yarn  in  this  bath  for  one  hour  at  120°  F. 
Keep  the  cotton  beneath  the  liquor  and  expose  the  bath  as  little  as  possible  to  the  action 
of  the  air.  After  dj^cing  rinse  well  in  water,  then  in  water  slightly  acidulated  with  sul- 
phuric acid,  and  finally  in  a  dilute  soap  bath.  Test  the  fastness  of  this  color  to  light, 
washing,  and  bleaching. 

The  Indanthrene  colors  are  best  applied  in  mechanical  dyeing  apparatus  so  that  the 
liquor  during  circulation  comes  into  contact  with  the  air  as  little  as  possible.  The  Indan- 
threne dyestuffs  are  somewhat  different  in  their  behavior  than  the  Indigo  dyes,  as  they 
exhaust  very  well  from  the  bath  and  the  color  dyes  up  directly  on  the  fiber  and  does  not 
require  a  subsequent  oxidation.  On  this  account  the  amount  of  coloring  matter  to  be 
used  may  be  based  directly  on  a  percentage  of  the  material  dj^ed. 

Exp.  156.  Use  of  Indanthrene  Yellow. — Prepare  a  dyebath  as  above,  using  10  per 
cent  of  Indanthrene  Yellow  G,  and  dye  a  test  skein  of  cotton  yarn  for  one  hour  at  a  tem- 
perature of  140°  F.  It  will  be  noticed  that  this  dyestuff  on  reduction  gives  a  blue  solu- 
tion and  that  the  cotton  is  blue  in  color  when  first  taken  from  the  dyebath.  For  the 
better  development  of  this  color,  after  dyeing,  squeeze,  rinse  in  water,  and  then  pass 
through  a  very  dilute  cold  solution  of  chrome  (0.1  gram  per  liter).  This  facilitates  the 
oxidation  of  the  color  very  materially.  Finally  wash  well  and  soap  as  usual.  Test  this 
color  for  fastness  to  light,  washing,  and  bleaching. 

Exp.  157.  Production  of  Fast  Pink  with  Indanthrene  Dyes. — Prepare  a  dyebath  as 
in  Exp.  155,  using  3  per  cent  of  Indanthrene  Red  B,  and  dye  a  test  skein  of  cotton  yarn 
for  one  hour  at  140°  F.  Wash  well  and  rinse  in  dilute  acid,  and  finally  soap.  This  color 
gives  a  rather  bright  pink  when  used  in  small  percentages  and  the  color  is  very  fast  to 
light,  washing,  acids,  and  bleaching.  By  combining  with  small  amounts  of  Indanthrene 
Yellow  R,  bright  yellowish  pinks  may  be  obtained. 

Exp.  158.  Use  of  Ciba  Blue. — Prepare  the  dyevat  as  follows:  Make  a  paste  with  0.5 
gram  of  Ciba  Blue  2B  (powder),  1  cc.  caustic  soda  (76°  Tw.)  solution,  and  some  hot 
water;  also  dissolve  2  grams  of  hydrosulphite  powder  (Blankit  T)  in  15  cc.  of  cold  water 
and  1  cc.  of  caustic  soda  solution.  Then  add  this  hydrosulphite  solution  to  the  dyestuff, 
dilute  to  400  cc.  with  hot  water  and  slowly  boil.  The  dyevat  should  then  be  com- 
pletely reduced  and  be  of  a  golden-yellow  color.  Dye  a  test  skein  of  cotton  yarn  in  this 
bath  for  thirty  minutes  at  170°  F.,  squeeze  well,  and  allow  to  oxidize  in  the  air  for  fifteen 
minutes;  then  rinse  well  in  cold  water,  and  finally  work  in  a  boiling  dilute  soap  bath. 
The  treatment  with  the  boiling  soap  bath  very  materiallj^  brightens  the  color,  and  also 
gives  it  greater  fastness  to  washing  and  bleaching.  A  still  greater  fastness  to  bleaching 
may  be  obtained  by  an  after-treatment  with  bluestone  in  the  usual  manner. 


CHAPTER  XIX 
ANILINE  BLACK 

1.  Chemistry  of  Aniline  Black. — The  method  of  dyeing  with  Aniline 
Black  was  discovered  by  Lightfoot  in  1863.*  It  is  a  dyestuff  formed 
on  the  fiber  by  the  proper  oxidation  of  aniline,  and  gives  a  very  fast  black 
color.  It  is  used  almost  exclusively  on  cotton,  although  it  may  be  applied 
by  special  means  to  both  silk  and  wool.  Its  principal  use  is  for  the  dyeing 
of  fast  blacks  on  hosiery,  and  for  the  dyeing  of  blacks  in  calico  printing. 

When  aniline  (also  its  homologues  toluidine  and  xylidine)  is  treated 
with  strong  oxidizing  agents  a  black  substance  is  obtained  known  as 
nigraniline,  though  there  is  said  to  be  an  intermediate  product  formed  called 
emeraldine,  which  is  a  green  compound.  The  chemical  composition  and  con- 
stitution of  Aniline  Black  have  never  been  satisfactorily  solved,  although 
the  properties  of  both  emeraldine  and  nig.raniline  have  been  thoroughly 
investigated. t  Besides  the  two  products  mentioned,  it  is  claimed  that  a 
third,  called  ungreenable  black,  is  also  formed  in  the  production  of  Aniline 
Black.  J  Unless  the  aniline  is  completely  oxidized,  the  black  obtained  is 
subject  to  the  defect  of  turning  green  on  exposure  to  the  air;  it  is  therefore 
important  to  secure  complete  pxidation. 

The  theory  of  Aniline  Black  dyeing  is  to  impregnate  the  cotton  material 
with  aniline  salt  and  an  oxidizing  agent,  and  then  by  ageing  or  by  treatment 

*  A  full  account  of  Lightfoot's  work  on  this  subject  may  be  found  in  his  book  entitled 
"  Chemical  History  and  Progress  of  AniHne  Black."  His  first  patent  on  Aniline  Black 
was  Eng.  Pat.  151  of  1863. 

t  See  Willstatter  and  Moore,  Berichte,  1907,  p.  2665;  Willstatter  and  Dorogi,  Berichte, 
1909,  pp.  2148,  4118;  Willstatter  and  Cramer,  Berichte,  1910,  p.  2976;  1911,  p.  2162; 
Nover,  Berichte,  1907,  p.  288;  A.  G.  Green,  Jour.  Soc.  Dyers  and  Col.,  1909,  p.  189; 
Green  and  Wolff,  Jour.  Soc.  Dyers  and  Col.  1913,  p.  105;  Green  and  Woodhead,  Jour. 
Chern.  Soc,  1910,  p.  2388;  1912,  p.  1117;  Green  and  Johnson,  Jour.  Soc.  Dyers  and  Col. 
1913,  p.  338. 

t  The  oxidation  of  aniline  oil  to  Aniline  Black  is  said  to  proceed  in  three  well-defined 
stages :  (a)  the  formation  of  emeraldine,  the  free  base  of  which  is  blue  though  its  acid 
salts  are  green  (this  being  the  color  of  the  dyed  cotton  as  it  comes  from  the  ager) ;  (b) 
the  conversion  of  emeraldine  into  nigraniline,  of  which  both  the  free  base  and  salts  are 
dark  blue,  but  which  are  reduced  by  sulphurous  acid  to  the  green,  emeraldine;  (c) 
the  conversion  of  the  nigraniline  into  the  ungreenable  Aniline  Black  which  is  not  reduced 
by  sulphurous  acid  to  emeraldine. 

451 


452  ANILINE  BLACK 

with  an  acid  solution  of  potassium  bichromate,  to  develop  the  black  dye- 
stuff  in  the  fiber.  Potassium  chlorate  is  the  favorite  oxidizing  agent 
used.  The  action  of  this  on  the  aniline  whereby  nigraniline  is  produced 
appears  to  be  rather  complex.  Chloric  acid  itself  docs  not  convert  aniline 
into  Aniline  Black,  as  a  solution  of  aniline  chlorate  can  be  boiled  without 
decomposition,  but  if  a  small  amount  of  acid  is  added  the  black  is  imme- 
diately formed.  The  same  result  is  produced  by  the  presence  of  certain 
metallic  salts  the  chlorates  of  which  are  readily  decomposed;  such  as 
copper,  manganese,  iron,  vanadium,*  and  cerium.  These  salts  act  as 
catalyzers,  bluestono  being  the  one  chiefly  employed.  The  bichromate  of 
aniline  acts  in  the  same  manner  as  the  chlorate. 

In  the  dyeing  of  Aniline  Black  on  cotton  there  is  precipitation  of  a  con- 
siderable amount  of  pigment  in  the  fiber,  as  the  weight  of  the  cotton  is 
increased  about  10  per  cent. 

Of  recent  years  a  new  process  for  dyeing  Aniline  Black  without  the  use 
of  oxidizing  agents  has  been  patented  by  A.  G.  Green.  In  this  method 
there  is  used  a  small  proportion  of  para-phenylene-diamine  or  para-amino- 
phenol  and  ageing  (oxidation)  in  the  air  is  resorted  to;  this  method  gives  a 
very  fine  black  that  is  ungrecnable  and  there  is  little  danger  of  tendering 
the  fiber,  t 

The  number  of  methods  employed  for  the  dyeing  of  Aniline  Black  are 
legion,  almost  eveiy  dyer  of  this  color  having  his  particular  formula  and 
method  of  operation.  In  general,  however,  the  different  methods  may  be 
divided  into  three  classes  as  follows: 

(1)  Single-bath  Black. — This  is  principally  used  for  dyeing  yarn  $  (eitlic 
as  warp  or  skein).  Frequently  a  bottom  of  Sulphur  Black  is  used  and  the 
Aniline  Black  is  dyed  over  this.     Chrome  is  used  for  the  oxidation. 

(2)  Aged  or  Oxidation  Black. — This  is  chiefly  used  for  dyeing  piece- 
goods  (cither  as  woven  cloth  or  knitted  fabrics  like  hosiery),  the  dye 
liquor  being  padded  into  the  goods.  Sodium  chlorate  and  blucstone  are 
used  as  the  oxidizing  agents;  though  with  Green's  process  para-phenylene- 
diamine  and  bluestone  are  so  used.  The  oxidation  is  effected  by  ageing 
the  goods  in  a  warm-air  chamber,  and  is  usually  completed  by  giving  a 
bath  of  chrome. § 

*  It  is  said  that  1  part  of  vanadium  (as  ammonium  vanadate)  is  sufficient  to  effect 
the  oxidation  of  270,000  parts  of  aniHne  salt  when  mixed  with  sodium  chlorate. 

t  The  catalytic  agent  in  this  case  is  the  para-phenylene-diamine  and  bluestone. 

J  The  single-bath  method  is  the  simplest  to  dye,  but  the  color  obtained  is  not  fast  to 
light  or  fulling;  it  also  crocks  more  or  less  badly  and  is  not  fast  to  light  bleaching.  It 
is  also  turned  green  by  sulphurous  acid.  It  is  most  used  for  black  yarn  for  the  export 
trade. 

§  The  production  of  Aniline  Black  bj'  the  ageing  process  is  chiefly  employed  for  the 
dyeing  of  hosiery;  it  gives  a  fine  shade  of  black  fast  to  light,  washing  and  bleaching;  it 
is  not  turned  green  by  sulphurous  acid. 


DYEING   ANILINE   BLACK 


453 


(3)  Steam  Black. — This  is  used  chiefly  in  cloth  dyeing  and  in  printing. 
Potassium  ferrocyanide  is  usually  employed  as  the  catalyzer  for  this  method ; 
the  cloth  being  padded  with  a  solution  of  aniline  salt,  sodium  chlorate,  and 
ferrocyanide,  then  steamed  for  a  few  minutes  in  an  ager.  If  an  alkaline 
paste  is  printed  on  before  steaming  the  black  does  not  develop  and  thus 
white  resists  may  be  obtained. 

2.  Dyeing  of  Aniline  Black;  One-bath  Method.*— A  large  number  of 
methods  or  recipes  for  this  process  of  dyeing  are  available,  among  which 
the  following  have  been  selected  (based  on 
the  dyeing  of  100  lbs.  of  cotton  yarn). 

(1)  Prepare  the  bath  with  5  lbs.  aniline 
oil,  12  lbs.  hydrochloric  acid,  and  6  lbs. 
chrome;  or  use  3.6  lbs.  anihne  oil,  3.6  lbs. 
hydrochloric  acid,  2  lbs.  sulphuric  acid,  9.8 
lbs.  chrome  and  |  lb,  bluestone.  Enter  the 
goods  cold,  work  one  hour,  then  raise  to 
boil  in  one  hour  and  dye  at  boil  for  one-half 
hour.     Rinse  and  soap  f  (Hochst). 

(2)  ]\Iake  two  solutions  as  follows:  (a) 
12  lbs.  aniline,  18  lbs.  hydrochloric  acid,  24 
lbs.  sulphuric  acid,  45  gallons  water;  and  (6) 
24  lbs.  chrome  in  45  gallons  water.  Allow 
to  cool;  mix  in  equal  parts  and  steep  the 
yam  therein  in  small  lots  (2  lbs.  at  a  time) 
for  a  few  minutes;  a  bronzy  black  is 
developed,  wring  out  and  steam  for  twenty 
minutes  at   3^   lbs.  pressure  t   when  a  jet 

black  that  is  ungreenable  will  be  produced,  wash  and  soap  at  the 
boil.  If  hydrochloric  acid  alone  is  used  a  bluish  black  will  be  obtained, 
and  sulphuric  acid  alone  gives  a  reddish  black;  but  a  mixture  of  the  two 
gives  a  jet  black  §  (Noelting). 

(3)  Prepare  a  bath  with  10  lbs.  chrome,  2  lbs.  sulphuric  acid  and  3  lbs. 


Fu 


229. — Vat  for  Dj-eing  Yarn 
With  Aniline  Black. 


*  The  one-bath  method  is  also  known  as  "  dyed  black."  The  dye  is  not  as  well  fixed 
in  this  process  as  with  an  aged  black;  also  the  color  usually  rubs  badly  and  has  a  dead 
flat  appearance.     But  the  fiber  is  not  so  liable  to  be  tendered  as  with  an  aged  black. 

t  For  soaping  use  5  to  10  lbs.  of  soap  per  150  gallons  of  water.  It  is  also  beneficial  to 
add  1  to  2  ozs.  of  olive  oil  to  the  soap  bath  as  this  gives  increased  softness  and  bright- 
ness. The  soaping  also  increases  the  fastness  of  the  color;  this  can  also  be  improved 
by  steaming. 

I  If  the  black  is  not  steamed  at  this  rather  high  temperature  the  color  is  liable  to 
turn  green. 

§  Logwood  may  be  used  for  topping  Aniline  Black  to  influence  the  tone  and  to  make 
the  color  more  bloomy.  The  Logwood  is  fixed  directly  as  there  is  already  sufficient 
chrome  on  the  fiber  to  act  as  a  mordant. 


454  AXILIXE   BLACK 

hydrochloric  acid  in  80  gallons  water;  stir  well  and  add  5  lbs.  aniline  salt 
previously  dissolved.  Work  the  yarn  in  the  cold  bath  for  1|  hours;  heat 
to  120°  F.,  in  one  hour  raise  to  175°  F.     Rinse  well  and  soap  (Badische). 

(4)  Prepare  a  bath  with  13  lbs.  aniline  salt,  20  lbs.  hydrochloric  acid, 
14  lbs.  chrome  (previously  dissolved  in  hot  water)  and  200  gallons  water.* 
Work  the  yarn  cold  for  one  hour;  raise  slowly  to  175°  F.  for  one-half  hour. 
Rinse  and  soap  (Oehler). 

(5)  Prepare  a  bath  with  14  lbs.  aniline  salt,  13  lbs.  chi'ome,  2  lbs.  blue- 
stone,  2  gallons  hydrochloric  acid  and  200  gallons  water.  Work  the  yarn 
in  cold  bath  for  one  and  one-half  hours,  then  raise  to  boil  in  forty-five 
minutes.  Then  work  in  fresh  bath  containing  4  lbs.  copperas  and  6  lbs. 
sulphuric  acid  for  ten  minutes  at  200°  F.  The  second  bath  removes  the 
bronzy  appearance  of  the  black.     Finally  wash  and  soap. 

(6)  For  a  cold  process  prepare  tlie  following  solutions:  (a)  8  lbs. 
aniUne  oil,  16  lbs.  hydrocliloric  acil,  4  gallons  water;  (6)  20  lbs.  sul- 
phuric acid,  4  gallons  water;  (c)  14  lbs.  chrome,  4  gallons  boihng  water; 
(d)  10  lbs.  copperas,  t  4  gallons  water.  Use  a  dyebath  of  300  gallons  cold 
water;  add  one-half  of  the  solutions  in  the  order  given;  work  the  yarn 
cold  for  one  hour;  hft  and  add  remainder  of  solution;  work  yarn  for  one 
and  one-half  hours  more.     Rinse  and  soap  {  at  the  boil. 

(7)  According  to  Hummel  Aniline  Black  may  be  dyed  in  the  form  of 
a  vat  like  Indigo. 

The  Anihne  Black  is  first  prepared  separately,  namelj^  b^^  heating  a 
solution  containing  aniline  hydrochloride,  potassimn  chlorate,  ammonium 
chloride,  and  copper  sulphate.  The  black  pigment  thus  produced  is  puri- 
fied by  boiling  with  water,  and  afterwards  with  alcohol.  It  is  then  heated 
with  a  solution  of  caustic  potash,  and  the  color-base  of  the  black  thus 
liberated  is  washed,  dried,  and  dissolved  in  fuming  sulphuric  acid.  This 
solution  is  poured  into  cold  water,  and  the  greenish  black  precipitate  thus 
produced  is  dissolved  in  caustic  alkali,  and  reduced  by  heating  with  the 
addition  of  glucose,  hydrosulphite  of  soda,  or  zinc  powder.  Ferrous  sul- 
phate and  lime  are  inoperative.  If  cotton  be  steeped  in  the  brownish 
yellow  solution  thus  obtained,  and  then  exposed  to  the  air,  it  acquires 
gradualty  a  blue  color.  By  submitting  this  color  to  a  supplementary  oxi- 
dation it  changes  to  a  light  graj^  or  deep  black,  according  to  the  concen- 

*  The  aniline  salt  should  be  dissolved  first,  then  the  acid  is  added  and  afterwards 
the  cold  solution  of  the  chrome. 

t  The  use  of  the  copperas  is  for  the  purpose  of  rendering  the  black  less  liable  to 
turn  green;  in  the  bath  it  is  changed  to  ferric  sulphate,  and  this  acts  as  an  oxidizing 
agent. 

f  Bj'  adding  a  small  amount  of  soda  ash  to  the  soap  bath  the  color  is  given  a  bluer 
tone.  The  same  effect  may  also  be  produced  bj'  using  a  small  amount  of  JMethyl  Violet, 
and  this  also  makes  the  color  faster  to  greening. 


OXIDATION  BLACK  455 

tration  of  the  vat.  A  judicious  combination  of  the  aniline  black  vat  with 
an  indigo  vat  may  yield  very  fast  deep  blues.* 

(8)  Whittaker  furnishes  the  following  formula:  20  lbs.  sodium  bichro- 
mate are  dissolved  in  hot  water  and  added  to  the  cold  [dyebath;  then 
add  10  lbs.  of  iron  liquor,  then  10  lbs.  sulphuric  acid,  and  stir  up  the  bath 
well.  Next  mix  up  10  lbs.  aniline  oil  with  10  lbs.  hydrochloric  acid  in  a 
bucket  with  a  little  water  to  prevent  fuming;  stir  until  the  aniline  is  com- 
pletely dissolved,  and  add  the  solution  to  the  dyebath  just  before  the 
yarn  is  entered.  Work  the  yarn  for  one  hour  cold,  then  slowly  raise  to  the 
boil.     Wash  off  well,  soap  at  the  boil  and  treat  with  an  emulsion  of  oil. 

3.  Aged  or  Oxidation  Black. — In  this  method  the  oxidation  is  principally 
effected  by  exposure  to  warm  moist  air,  though  it  is  necessary  to  have 
present  with  the  aniline  on  the  fiber  some  form  of  catalyzer,  or  "  carrier  " 
of  oxygen,  as  the  oxygen  of  the  air  does  not  act  directly,  f 

The  dye  liquor  with  its  various  ingredients  is  made  up  in  a  rather  con- 
centrated form,  and  in  the  case  of  cloth,  the  liquor  is  padded  on  in  a  suit- 
able padding  machine.  In  the  case  of  hosiery  (which  is  veiy  largely  dyed 
by  this  process)  the  liquor  is  padded  into  the  made-up  hose  in  a  tramping 
machine  which  is  known  as  a  "  tom-tom,"  the  liquor  being  forced  into  the 
fiber  by  the  blows  of  wooden  hammers  that  rise  and  fall.  After  thorough 
saturation  and  removal  of  the  excess  of  liquor,  the  goods  are  dried  and  aged 
in  a  suitable  room  or  apparatus'in  wliich  a  moist  heat  can  be  maintained.  % 

*  Aniline  Black  is  sometimes  used  in  connection  with  substantive  blue  or  black  dyes 
on  cotton  in  order  to  obtain  a  deep  fast  black.  After  the  cotton  has  been  dyed  with 
the  substantive  color  it  is  treated  with  a  cold  bath  prepared  as  follows :  4  per  cent  chrome, 
2  per  cent  copper  sulphate,  3  per  cent  aniline  salt,  and  4  per  cent  sulphuric  acid.  The 
goods  are  worked  in  the  cold  bath  for  one-half  hour,  and  then  the  bath  is  gradually 
heated  to  160°  F.  and  run  at  that  temperature  for  one  hour.  Squeeze,  allow  the  goods  to 
cool  down  in  the  open  air,  wash,  soap,  and  dry.  In  preparing  the  bath  the  chrome  and 
bluestone  should  be  dissolved  separately  in  as  little  hot  water  as  possible,  so  as  not  to 
increase  the  temperature  of  the  cold  aniline  bath,  and  both  of  these  solutions  should  be 
added  directly  to  the  bath  just  before  entering  the  cotton.  The  black  obtained  in  this 
manner  is  much  faster  than  that  produced  by  the  substantive  dyes  alone,  also  the  fiber 
is  better  preserved  than  when  oxidation  Aniline  Black  is  used,  and  the  color  is  faster  to 
rubbing  than  when  the  single-bath  Aniline  Black  process  is  used. 

t  In  the  oxidation  there  are  four  essential  ingredients :  (a)  aniline  (either  oil  or  salt) ; 
(6)  oxidizing  agent  (usually  sodium  chlorate) ;  (c)  an  oxygen  carrier  (copper  sulphide, 
copper  sulphate  or  vanadium  salt) ;  (d)  a  hygroscopic  substance  (ammonium  chloride) . 
The  latter  also  acts  by  its  dissociation  at  the  high  temperature  of  ageing  in  starting  the 
reaction. 

t  When  the  goods  are  squeezed  or  hydro-extracted,  they  should  contain  about  their 
own  weight  of  liquor.  Sometimes  the  padding  liquor  is  made  more  viscid  by  the  addi- 
tion of  starch  or  dextrin.  This  favors  a  more  even  distribution  and  penetration  of  the 
dye  liquor.  A  recipe  of  this  kind  especially  suitable  for  padding  yarn  is  as  follows: 
(a)  3  lbs.  aniline  oil  are  mixed  with  3  lbs.  hydrochloric  acid;  (6)  1§  lbs.  bluestone,  1| 
lbs.  ammonium  chloride  and  Ij  lbs.  potassium  chlorate  are  dissolved  in  water;    (c) 


456  ANILINE  BLACK 

The  proper  regulation  of  the  temperature  and  moisture  is  veiy  important  in 
order  to  prevent  tendering,  as  much  acid  fume  is  developed  in  the  ageing. 
Special  ageing  machines  arc  built  so  as  to  permit  of  accurate  regulation  of 
air,  heat,  and  steam.  The  ageing  is  usually  done  at  a  temperature  of  110 
to  115°  F.  Provision  should  also  be  made  to  keep  the  goods  in  motion; 
in  the  case  of  cloth  the  material  is  generally  slowly  passed  through  the  ager 
continuously;  with  hosiery,  a  large  rotating  cage  is  usually  provided  which 
tumbles  the  goods  about  so  as  to  expose  all  parts  uniformly  to  the  air  and 
steam.  Unevenness  of  treatment  is  to  be  carefully  avoided,  otherwise 
streaks  and  stains  will  result. 

When  the  goods  have  been  sufficiently  aged  they  show  a  dark  green  or 
blackish  green  color.  The  time  of  ageing  is  important,  and  can  be  told 
only  by  experience  with  the  special  form  of  goods,  formula  of  dye,  and  the 
conditions  of  ageing.  It  is  also  important  that  proper  moisture  be  main- 
tained during  the  ageing,  as  this  is  very'  essential,  not  only  to  the  develop- 
ment of  a  good  black,  but  also  to  prevent  tendering  of  the  cotton.*  Ex- 
perienced workmen  can  usually  tell  when  the  ageing  is  properly  completed 
by  the  color  of  the  goods.  After  ageing,  the  goods  are  chromed  in  a  bath 
containing  4  ozs.  chrome  and  1  oz.  sulphuric  acid  per  10  gallons  water  at 
160°  F.  They  are  finally  soaped  hot  in  a  solution  containing  4  ozs.  soap  per 
10  gallons  water,  then  rinsed  and  dried.  If  the  chroming  is  done  at  a 
higher  temperature  the  black  will  show  a  redder  shade. 

The  following  are  some  recipes  recommended  for  the  ageing  method  of 
dyeing  Aniline  Black: 

(1)  For  1000  parts  of  liquor  of  15°  Tw.,  use  126  parts  aniline  salt,  40 
parts  sodium  chlorate,  150  parts  aluminium  acetate  (22°  Tw.),  5.7  parts 
aminonium  chloride,  and  3  parts  bluestone.  The  dj^e  liquor  for  padding  is 
diluted  to  12°  Tw.  and  refreshed  with  additions  of  above  standard  solution 
of  15°  Tw.  After  impregnation,  diying,  and  ageing  chrome  for  one-half 
hour  at  140°  F.,  in  a  bath  containing  2|  per  cent  chrome,  ^  per  cent 
aniline  salt  and  |  per  cent  sulphuric  acid.     Rinse  well  and  soap.    (Hochst.) 

(2)  Pad  with  the  'ollowing  liquor,  which  is  made  from  the  solutions 
prepared  separately,  mixed  cold  and  made  up  to  100  gallons  with  water: 
120  lbs.  aniline  salt  in  30  gallons  water;  5|  lbs.  bluestone  in  10  gallons 
water;  38  lbs.  sodium  chlorate  in  8  gallons  water;  4  lbs.  ammonium  chloride 
in  3  gallons  water;    5  gallons  aluminium  acetate  solution     (150°  Tw.). 

§  lb.  starch  is  boiled  up  with  water  and  diluted.  When  cold,  (a)  is  mixed  with  (6)  and 
then  (c)  is  added  and  made  up  to  5  gallons  with  water.  Pad  in  this  liquor,  age  at  90°  F., 
chrome,  wash,  and  soap. 

*  The  goods  should  not  be  washed  between  the  ageing  and  the  chroming.  The 
ageing  usually  lasts  from  six  to  eight  hours.  During  the  ageing  it  is  important  that  drops 
of  water  do  not  come  in  contact  with  the  goods,  as  gray  spots  will  be  formed.  Also 
alkali  must  not  come  in  contact  with  the  material  before  ageing,  as  this  will  form  a  resist 
to  the  development  of  the  black  and  make  a  white  spot. 


OXIDATION    BLACK 


457 


Impregnate  so  that  cloth  retains  own  weight  of  hqiior;    dry  at  100°  F.; 
age  for  several  hours  at  100°  F.,  then  chrome  and  soap.     (Oehler.) 

(3)  Green's  method  (Eng.  Pat.  16189,  of  1907),  which  is  said  to  be 
very  successful,  is  as  follows:  The  padding  liquor  consists  of  a  solution  of 
48  parts  cupric  cliloride,  140  parts  ammonium  chloride,  and  14  parts  sodium 
meta-bisulphite  in  500  parts  cold  water;  this  is  added  to  a  solution  of  50 
parts  aniline,  2  parts  para-phenylene-diamine,  15  parts  hydrochloric  acid, 
and  15  parts  formic  acid  in  1500  parts  cold  water.  The  material  is  padded 
with  this  solution,  dried,  aged,  and  chromed  as  usual. 


Fig.  230.— Impregnating  Machine  for  Yarn.     (Haubold.) 


(4)  Vanadium  salt  is  sometimes  used  as  a  catalyzer  as  follows:  Pre- 
pare a  liquor  with  90  parts  aniline  salt,  20  parts  aniline  oil,  40  parts  sodium 
chlorate;  5  parts  vanadium  chloride  solution  (1  :  100),  and  845  parts  water. 
Pad  the  material  with  this  solution,  dry,  age,  and  chrome  as  usual.  The 
vanadimn  cliloride  solution  is  prepared  ^\ith  10  parts  ammonium  vana- 
date, 70  parts  hydrochloric  acid,  40  parts  water,  7  parts  glycerin;  make 
up  to  1000  parts  with  water  and  heat  until  the  solution  becomes  blue  in 
color.  Vanadium  black  is  more  used  in  printing  than  in  dyeing,  as  in  using 
it  there  is  great  danger  of  tendering  the  fiber. 

Whittaker  gives  the  following  formulas  for  aged  Aniline  Black : 


458 


ANILINE   BLACK 


(5)  For  a  black  fast  to  bleaching  on  yarn,  using  bluestone,  dissolve 
60  parts  aniline  salt  in  320  parts  water  and  make  perfectly  neutral,  if 
necessary,  by  the  addition  of  aniline  oil;  2f  parts  copper  sulphate  in  50 
parts  of  water,  19  parts  sodium  chlorate  in  37  parts  of  water,  2  parts  ammo- 
nium chloride  in  12  parts  water,  and  24  parts  aluminium  acetate  15°  Tw. 
On  mixing  these  together  the  resulting  liquor  should  stand  at  about  12° 
Tw.  Pad  the  yarn  in  this  liquor  2  lbs.  at  a  time,  and  WTing  out  so  that  it 
holds  its  own  weight  of  Hquor.     Drj'  in  a  hot  room  at  95°  F.  on  sticks  which 


Fig.  231. — Yarn  Drying  Machine.     (Haubold.) 


have  been  saturated  with  the  above  liquor  to  avoid  stick  marks.  Turn 
the  yarn  every  two  hours  (the  workmen  should  have  dry  hands,  as  wet 
hands  will  make  finger  marks).  When  dry  turn  steam  into  the  hot  room 
till  the  drj'  bulb  shows  95°  F.  and  the  wet  bulb  86°  F.  Keep  at  this  tem- 
perature for  six  hours,  when  the  yarn  shows  a  dark  bottle-green  color. 
Then  chrome  for  fifteen  minutes  at  180°  F.  with  4  per  cent  of  chrome  and 
1  per  cent  of  sulphuric  acid.  This  gives  a  jet  black  color.  Wash  well  and 
soap  for  fifteen  minutes  at  180°  F. 


STEAM  BLACK 


459 


(6)  In  another  recipe  copper  sulphide  in  the  form  of  a  paste  is  used  as 
the  oxygen  carrier.  It  is  made  as  follows:  37|  parts  copper  sulphate  are 
dissolved  in  150  parts  water;  add  39  parts  sodium  sulphide  (crystals)  in  100 
parts  water;  filter  and  press  to  54  parts,  in  which  form  it  is  used.  The 
dye  liquor  is  made  with  15  parts  aniline  salts  made  neutral  with  aniline 
oil,  5  parts  copper  sulphide  paste,  5  parts  sodium  chlorate  and  75  parts 
water.  Cloth  is  padded  with  this  liquor  and  then  squeezed  till  it  retains 
its  own  weight  of  the  solution.  Dry  and  give  a  three-minute  passage 
through  an  ager  at  140°  F.     Then  chrome,  wash,  and  soap.* 


Fi^.  232. — Tom-Tom  Machine  for  Hosiery.      (Delahunty  Dyeing  Machine  Co.) 


Steam  Black  with  Aniline. — This  is  really  a  rapid  method  of 
ageing  the  Aniline  Black  by  steaming  and  ferrocyanide  of  potash  is  used  as 
the  carrier  of  oxygen.  The  ageing  is  carried  out  in  a  steam  chamber  through 
which  the  goods  pass  continuously,  f  The  method  is  principally  used  for 
black  on  piece-goods  and  for  printing.  After  impregnation  of  the  material 
with  the  dye  liquor,  the  pieces  are  dried  rapidly,  steamed  for  about  three 

*  The  copper  method  is  used  more  than  the  vanadium  process  because  with  the  latter 
the  hquor  oxidizes  more  quickly,  and  hence  it  is  not  as  stable. 

t  It  is  said  that  the  steam  black  gives  a  color  less  liable  to  turn  green  than  the  black 
obtained  by  the  ageing  process.  Also  the  danger  of  tendering  the  fiber  is  less.  As  the 
color  is  not  developed  so  far  in  the  steaming  the  after-chroming  must  be  more  thorough. 


460 


ANILINE   BLACK 


minutes,  chromed,  washed,  and  soaped.  The  following  are  typical  recipes 
for  padding  liquors : 

(a)  Prepare  a  liquor  with  75  parts  aniline  salt,  35  parts  sodium  chlorate, 
40  parts  potassium  ferrocyanide,  and  make  up  with  water  to  1000  parts. 

(6)  Use  40  lbs.  aniline  salt  in  6  gallons  water,  26  lbs.  potassium  ferro- 
cyanide in  15  gallons  water,  and  15  lbs.  sodium  chlorate  in  3  gallons 
water.  For  light  delicate  goods,  it  is  well  to  make  the  padding  liquor 
slightly  alkaline  with  ammonia  (Oehler). 

5.  Aniline  Black  on  Other  Fibers. — Owing  to  the  reducing  action  of 
wool  and  silk  Aniline  Black  does  not  develop  on  these  fibers  as  on  cotton, 
also  owing  to  the  very  satisfactory  blacks  available  for  wool  there  is  no 


Fig.  233. — Oxidizing  Machine  for  Hosiery. 


especial  call  for  Aniline  Black  in  this  field.*  A  special  application  of  Aniline 
Black,  however,  is  made  to  a  class  of  silk  and  mohair  pile  fabrics  used  for 
making  imitation  chinchilla,  giving  the  goods  a  black  color  with  white  tips. 
The  process  is  carried  out  as  follows :  Work  the  goods  for  fifteen  minutes 
in  a  cold  bath  containing  5  parts  potassium  permanganate,  7  parts  magne- 
sium sulphate,  f  and  100  parts  water.  Gradually  raise  the  temperature  to 
120°  F.  for  one-half  hour,  then  wash  and  diy.     The  fiber  now  has  a  dark- 

*  Lightfoot  (in  1865)  showed  that  by  chlorinating  the  wool  before  dyeing  or  printing 
the  fiber  could  be  so  prepared  as  to  take  the  color  of  Aniline  Black.  Many  other 
processes  have  also  been  suggested  for  the  application  of  Aniline  Black  to  wool,  but 
none  of  these  has  had  any  commercial  success. 

t  The  magnesium  sulphate  is  used  to  neutralize  the  caustic  alkali  that  is  liberated 
from  the  permanganate  and  so  prevent  its  action  on  the  fiber. 


DIPHENYL  BLACK 


461 


brown  color  due  to  the  oxide  of  manganese.  To  make  the  white  tips  a 
"cutting"  Kquor  is  prepared  as  follows:  3  qts.  hydrogen  peroxide,  1 
pint  acetic  acid  and  1  oz.  oxalic  acid  in  1  pint  water.  This  is  suitably 
thickened  with  British  gum  to  make  a  paste  which  is  brushed  on  the  goods 
in  any  desired  design.  The  cloth  is  then  dried  and  the  black  developed 
by  washing  for  ten  minutes  in  a  cold  bath  of  1000  parts  water,  5  parts 
aniline  oil  and  5  parts  sulphuric  acid.  The  color  is  then  further  developed 
by  soaping  at  100°  F.  with  the  addition  of  a  little  ammonia.  The  cutting 
paste  acts  as  a  resist  and  leaves  the  fiber  white. 

6.  Diphenyl  Black. — This  is  an  oxidation  black  similar  to  Aniline  Black, 
but  uses  para-amino-diphenylamine   in  place  of  aniline.     It  is  dyed  in 


Fig.  234. — Tom-Tom  with  Reciprocating  Motion.     (Haubold.) 


practically  the  same  manner  by  the  ageing  process,  but  an  after-chroming  is 
not  necessary.  It  is  also  claimed  to  be  ungreenable,  and  not  to  injure  the 
fiber.  It  is  chiefly  employed  on  piece-goods  and  for  suiting.  The  pad- 
ding liquor  is  made  up  as  follows:  (Hochst.)  (a)  6  lbs.  gum  tragacanth 
gum  (1:  10)  and  1  gallon  water,  4  lbs.  Diphenyl  Black  Base  dissolved  warm 
in  5  lbs.  lactic  acid  (50  per  cent)  and  13  lbs.  acetic  acid  (40  per  cent) ;  add 
water  to  make  up  to  50  lbs.;  (6),  21  lbs.  aluminium  chloride  (53°  Tw.), 
6.4  ozs.  cupric  chloride  (77°  Tw.),  and  4  gallons  water;  then  add  3  lbs. 
sodium  chlorate  dissolved  in  1  gallon  boiling  water  and  1  lb.  oil  of  tur- 
pentine;   dilute  with  water  to  100  lbs.     After  padding,  age  for  one-half 


462 


ANILINE  BLACK 


hour  and  steam  in  a  Mather-Platt  steamer  for  two  minutes;    soap  at  140° 
F.,  rinse  and  drj'.* 

7.  Paramine  Brown. — This  is  a  color  produced  on  the  fiber  by  the 
oxidation  of  para-phenylene-diamine.  f  It  is  dyed  in  a  manner  similar 
to  that  of  steam  Aniline  Black.  It  is  dyed  in  the  following  manner 
(Badische) :  Dissolve  20  parts  Paramine  (para-phenylene-diamine)  in 
300  parts  hot  water  and  dilute  with  450  parts  cold  water;  add  I5  parts 
Rongalite  C,  and  then  add  successively  20  parts  sodium  chlorate  dissolved 
in  50  parts  water,  10  parts  ammonium  chloride  dissolved  in  50  parts  water, 
15  parts  ammonium  vanadate  solution  (1:  1000)  and  40  parts  tartar  emetic 
solution  (prepared  by  dissolving  40  parts  tartar  emetic  in  620  parts  water 


Fig.  235. — Ageing  Machine  for  Cloth.     (Zittauer.) 

and  340  parts  glycerin).  Dilute  to  1000  parts.  In  one  hour  the  solution 
should  become  colorless.  Pad  the  cloth  in  this  liquor,  diy  at  105  to  115° 
F.,  steam  for  five  minutes  in  the  ager,  rinse  and  soap.  Instead  of  steaming 
the  goods  may  be  passed  through  a  warm  solution  of  3  parts  chrome  to 
1000  parts  water.  The  tartar  emetic  is  used  for  the  purpose  of  delaying 
the  oxidation,  and  is  chiefly  important  when  making  resist  prints. 

*  Diphenj4  Black  Base  was  para-amino-diphenylamine  while  Diphenyl  Black  Oil  DO 
consisted  of  1  part  amino-diphenylamine  dissolved  in  3  parts   aniline  oil. 

t  Paramine  is  the  name  under  which  para-phenylene-diamine  is  sold  when  used  for 
this  purpose.  Fuscamine  is  a  more  yellowish  brown  obtained  by  using  para-amino- 
phenol  in  place  of  Paramine.  It  is  also  known  as  Bistramine  Brovm.  A  similar  color 
known  as  Ortamine  Brown  is  prepared  from  ortho-dianisidine. 


EXPERIMENTAL  STUDIES 


463 


8.  Experimental.  Exp.   169.  After-Chromed  Method  for  Aniline   Black. — Prepare 

a  bath  contaming  the  following:    15  grams  potassium    chlorate;  10  grams  b.luestone; 
26  grams  aniline    hydrochloride;  200  cc.  water.     Use  a  test  skein   of  cotton   which 


Fig.  236. — Drying  and  Ageing  Machine  for  Warps.     (Zittauer.) 


Fig.  237. — Machine  for  Dyeing  Warps  with  Aniline  Black.  ^ 

has  been  well  wet    out,  and  saturate  it  thoroughly  with  the  above  solution;    squeeze^ 
and  dry  in  a  hot-air  chamber  until  the  cotton  is  of  a  uniform  green  color;  then  work 
for  one-half  hour  at  180°  F.  in  a  bath   containing:    3  grams  potassium  bichromate;  2 
grams  sulphuric  acid;  300  cc.  water.   -Finally  soap  and  wash.  * 


464 


ANILINE   BLACK 


Exp.  160.  One-bath  Process. — Prepare  a  bath  as  follows:  300  cc.  water;  10  grams 
aniline  salt;  3  grams  potassium  bichromate.  The  aniline  salt  is  dissolved  in  the  water, 
after  which  the  potassium  bichromate  is  dissolved  in  a  little  water  and  also  added. 
The  cotton  is  worked  in  this  solution  cold  for  one  hour,  then  the  temperature  is  grad- 
ually raised  to  150°  F. 

The  process  may  be  varied  somewhat  by  adding  to  the  bath  only  one-half  the  above 
ingredients  at  a  time.  The  more  concentrated  the  solution,  and  the  greater  its  acidity 
the  more  rapidly  will  the  dyeing  take  place.  E.xcess  of  acid  and  prolonged  heating  tend 
to  give  bronzj'-colored  blacks,  and  much  of  the  coloring  matter  will  only  be  superficially 
fixed.  If,  however,  the  heating  has  been  of  only  short  duration,  the  black  will  have  a 
bluish  tone,  and  is  liable  to  turn  green  when  treated  with  acids.     The  temperature  of 


r 


I 


Fig.  238.— Aniline  Black  Ageing  Machine.     (Mather  &  Piatt.) 

the  bath  should  be  raised  very  gradually,  else  there  will  be  a  considerable  loss  of  coloring 
matter  by  precipitation  in  the  bath.     After  dyeing  the  cotton  should  be  well  washed  in 
water,  and  then  in  a  boiling  soap  solution  containing  5  to  10  grams  of  soap  per  liter,  to 
which  a  little  soda  ash  may  also  be  added.      Due  to  the  strong  acidity  of  the  bath  un- 
less the  process  is  conducted  very  carefully  the  cotton  will  be  liable  to  become  tendered. 
Exp.  161.  Cold  Process  for  Aniline  Black. — In  this  method  the  operation  is  con- 
ducted  entirely  in   tlie   cold.     Pro]xire  a   bath   containing:     16  cc.  hydrochloric  acid; 
12  cc.  sulphuric  acid;   10  grams  aniline  oil;  20  grams  potassium  bichromate;   10  grams 
^opperas;  200  cc.  water.     Work  the  cotton -in  this  bath  cold  until  a  full  black  color 
^s  developed,  which  will  require  from  one  to  two  hours.     Hydrochloric  acid  alone  tends 
to  produce  bluish  blacks,  while  sulphuric  acid  gives  a  reddish  hue,  hence  a  mixture  of 
the  two  acids  gives  a  more  pleasing  tone  to  the  color  finally  produced.     The  ferrous 
sulphate  is  added  for  the  purpose  of  rendering  the  black  less  liable  to  turn  green;   in 


EXPERIMENTAL  STUDIES 


465 


=3 


a 
IS 


m 


m 


466 


ANILINE   BLACK 


the  bath  it  Is  changed  to  ferric  sulphate,  which  acts  as  an  oxidizing  agent.  After 
dj'eing  cotton  must  be  washed  and  well  boiled  in  a  soap  solution.  The  use  of  soap  alone 
gives  blacks  of  a  violet  tone,  while  if  soda  ash  is  added  a  bluer  tone  results. 

In  order  to  render  the  black  obtained  either  by  this  method  or  the  preceding  ungreen- 
able,  it  is  necessary  to  give  the  cotton  a  further  oxidation.  For  this  purpose  the  follow- 
ing bath  is  used:  20  grams  copperas;  5  grams  chrome  and  18  cc.  sulphuric  acid;  70  cc. 
water.  To  500  cc.  water  add  5  cc.  of  this  solution  and  work  the  cotton  therein  for  three- 
quarters  of  an  hour  at  170°  F.,  then  wash  well  and  soap. 

Another  method  for  ])reventing  the  black  from  becoming  green  Is  to  dye  it  in  a  weak 
solution  of  Methyl  \'iolet,  which  may  be  done  in  the  soap  bath.  This  basic  dyestuff 
evidently  combines  with  the  cotton  by  reason  (jf  the  fiber  having  been  more  or  less  con- 
verted into  oxycellulose.  The  effect  of  the  green  and  violet  produces  a  bluish  black, 
hence  the  color  appears  to  remain  unchanged.     . 


Fig.  240. — Machine  for  Oxidizing  in  Hot  Flue.     (Zittauer.) 


Exp.  162.  Use  of  Bluestone  in  Aniline  Black. — This  is  a  very  common  ingredient  in 
formulas  for  the  dyeing  of  Aniline  Black.  Make  a  solution  as  follows:  25  grams  aniline 
hydrochloride,  3  grams  bluestone,  5  grams  ammonium  chloride,  and  100  cc.  of  water. 
Work  a  test  skein  of  cotton  in  this  bath  cold  until  thoroughlj^  impregnated;  squeeze, 
and  oxidize  in  a  fresh  bath  containing  10  grams  chrome,  1  gram  sulphuric  acid,  and  200 
cc.  water.     Wash  well  and  finally  soap. 

Exp.  163.  Ageing  Process  for  Aniline  Black. — The  best  blacks  are  obtained  with 
aniline  which  has  been  aged  for  some  time  in  a  hot-air  chamber  containing  the  proper 
amount  of  moisture.     Make  three  solutions  as  follows: 

a.  Dissolve  12  grams  potassium  chl.orate  in  a  small  amount  of  water. 

b.  Dissolve  22  grams  potassium  ferrocyanide  in  100  cc.  water. 

c.  Dissolve  35  grams  aniline  hydrochloride  in  100  cc.  w^ater. 

Mix  these  three  solutions  cold.  Work  a  test  skein  of  cotton  in  the  bath  for  one-half 
hour  cold;  squeeze,  and  age  in  a  hot-air  chamber  at  about  175°  F.,  the  air  of  which  is 
not  too  dry.     The  material  should  turn  a  dark  green  during  this  treatment;   then  work 


EXPERIMENTAL  STUDIES 


467 


468 


ANILINE  BLACK 


Fig.  242. — Steaming  Cottage  for  Hank  Yarn,  the  Carriage  Provided  with   Wooden 

Ears. 


Fig.  243. — Yarn  Impregnating  and  Wringing  Machine.     (Haubold). 


EXPERIMENTAL  STUDIES  469 

for  one-half  hour  at  160"  F.  in  a  bath  containing  2  per  cent  chrome.  Finally  wash  and 
soap. 

Exp.  164.  Use  of  Manganese  Chloride  in  Aniline  Black. — This  salt  maj-  be  used  for 
the  production  of  the  oxide  of  manganese  on  the  hher,  which  acts  as  an  oxidizing  agent 
with  aniline  and  thereby  produces  the  black.  Work  a  test  skein  of  cotton  in  a  cold 
bath  containing  10  per  cent  manganese  chloride;  squeeze,  and  pass  through  a  bath  con- 
taining 5  per  cent  caustic  soda  cold  for  fifteen  minutes.  This  causes  the  lower  oxide  of 
manganese,  MnO,  to  be  precipitated  on  the  cotton;  rinse,  and  work  for  fifteen  minutes 
cold  in  a  bath  of  chloride  of  lime  at  2°  Tw.  in  order  to  oxidize  the  manganese  compound 
to  the  higher  oxide,  Mn20.3.  Rinse,  and  pass  through  a  solution  containing  10  grams 
aniline  hydrochloride  in  200  cc.  water,  acidified  with  2  cc.  hydrochloric  acid. 

Exp.  165.  Use  of  Vanadium  in  Aniline  Black  Dyeing. — The  salts  of  this  element 
appear  to  act  as  good  carriers  of  oxygen  in  Aniline  Black  dyeing,  but  their  expense  has 
prohibited  their  general  use.  Prepare  a  bath  containing:  10  grams  aniline  hydrochlo- 
ride, 0.1  gram  ammonium  vanadate,  and  100  cc.  water;  impregnate  a  test  skein  of  cot- 
ton with  this  solution;  squeeze,  age  in  hot-air  room  as  before  described,  and  then  oxidize 
in  chrome  bath,     Finally  wash  well  and  soap. 


CHAPTER   XX 
USE  OF  LOGWOOD  IN  DYEING 

1/  General  Use  of  Natural  Dyes. — Previoui?  to  the  discovery  of  the 
coal-tar  dyes  the  textile  colorist  had  to  rely  upon  either  the  mineral  pig- 
ments or  the  dyestuffs  derived  from  the  various  vegetable  substances  for 
the  production  of  his  effects.  The  vegetable  dyes  nearly  all  belong  to  the 
mordant  class  of  dyestuffs,  though  a  few  such  as  Turmeric,  SafSower,  and 
Annatto  exhibit  substantive  properties  to  a  certain  degree,  and  may  be 
dj^ed  directly  on  cotton.  In  general,  however,  in  using  the  natural  dye- 
woods  on  either  wool  or  cotton  it  is  first  necessary  to  mordant  the  material 
in  the  usual  manner  with  metaUic  salts.* 

The  coloring  matters  present  in  the  dyewoods  were  usually  extracted 
by  the  dyer  himself  l^y  simply  boiling  the  rasped  wood  in  water  and  using 
this  solution  as  a  dyebath.  Under  these  conditions,  however,  the  coloring 
matter  so  obtained  was  never  in  a  pure  condition,  but  was  contaminated 
with  more  or  less  resinous  and  tannin  matter  which  acted  frequently  in  a 
deleterious  manner  in  the  dj^eing.  The  first  application  of  chemical 
science  to  the  art  of  dj'eing  was  the  attempt  to  manufacture  purer  and 
more  homogeneous  dye  products  from  the  extracts  of  the  various  dyewoods 
or  other  vegetable  coloring  matters.  At  the  present  time  the  use  of  the 
natural  dyewoods  has  almost  disappeared  with  the  exception  of  Logwood, 
Fustic,  Quercitron, and  Indigo;  and  even  the  latter  is  now  a  coal-tar  product 
which  is  rapidly  driving  the  natural  article  from  the  market.  Logwood  still 
holds  its  own  for  the  production  of  cheap  l^lacks  on  wool  and  cotton,  and  it 
is  also  largely  used  in  the  l^lack  dyeing  of  silk.  Fustic  is  used  to  some  extent 
in  connection  with  the  foregoing  to  tone  the  shade  of  the  black  obtained 
but  even  its  use  in  this  manner  is  gro^dng  less  and  less,  being  replaced  by 
other  yellow  coloring  matters  which  possess  a  greater  degree  of  fastness. 
Cutch  is  stiU  used  for  the  production  of  brown  shades  on  cotton,  but  it 
is  more  used  as  a  tannin  mordant  than  as  a  self  color. 

*  The  affinity  of  the  natural  dyestuffs  for  wool  is  based  upon  the  same  general  princi- 
ples as  in  the  case  of  the  coal-tar  dj-es.  The  majority  of  the  natural  dyes  belong  to  the 
mordant  class,  though  a  few  will  combine  with  wool  directly  after  the  manner  of  acid 
dyes,  and  a  limited  number  act  in  the  same  manner  as  substantive  dyes. 

470 


CHARACTERISTICS  OF  LOGWOOD  471 

The  natural  dyewoods  yield  coloring  matters  from  which  may  be  dyed 
black,  red,  brown,  yellow,  blue,  violet,  etc.;  there  is,  however,  no  good 
green  dye  among  the  list  of  natural  dyestuffs.  The  colors  obtained  with 
the  natural  dyes,  as  a  rule,  are  rather  dull  in  appearance,  and  many  of 
them  are  of  questionable  fastness,  there  being  many  of  the  mordant  coal- 
tar  dyes  which  are  far  superior  in  this  respect. 

2.  Logwood. — Logwood  is  obtained  from  the  Campeachy  wood, 
known  botanically  as  Hcematoxylin  Campechianujn;  it  is  a  large  tree  and 
grows  principally  in  tropical  and  sub-tropical  America.*  The  wood  itself 
is  really  a  red- wood,  but  the  color-lake  as  finally  developed  is  black  or  blue 
depending  on  its  intensity.  When  freshly  cut  the  wood  is  colorless  or 
looks  about  like  that  of  any  other  tree;  on  exposure  to  the  influence  of  the 
oxygen  of  the  air,  however,  the  outside  of  the  wood  becomes  of  a  dark 
reddish  brown  color,  due  to  the  development  of  the  coloring  matter. 
The  coloring  principle  of  Logwood  is  called  hematoxylin  f  and  this  on  oxida- 
tion yields  hematine,  which  is  the  real  coloring  matter  of  the  prepared 
Logwood.  X  In  order  to  prepare  the  wood  for  use  by  the  dyer,  the  logs, 
after  having  the  outer  sapwood  stripped  off,  are  either  rasped  or  chipped, 
the  chips  being  placed  in  large  heaps  and  moistened  with  water.  These 
heaps  are  turned  over  from  time  to  time  to  allow  the  oxygen  of  the  air  free 
access  to  the  wood.  Fermentation  occurs,  which  results  in  the  formation  of 
the  hematine.  §     The  dye  wood  in  this  state  may  now  be  used  by  the  dyer, 

*  Logwood  was  not  introduced  into  dyeing  until  after  the  discovery  of  America. 

t  Hematoxylin  may  be  prepared  from  Logwood  by  extracting  the  freshly  prepared 
aqueous  solution  of  the  wood  with  ether,  and  subsequently  crystallizing.  The  purified 
crystals  are  white  and  prismatic  in  form.  On  exposure  to  the  air  they  soon  become 
oxidized  to  hematine,  which  is  of  deep  cherry-red  color.  The  fresh  wood  contains  about 
8  to  10  per  cent  of  hematoxylin. 

t  The  coloring  matter,  as  it  exists  in  the  wood,  is  probably  in  the  form  of  a  glucoside. 
When  freshly  cut  the  wood  is  colorless,  and  looks  like  any  other  tree;  but  soon,  on 
exposure  to  the  influence  of  the  oxygen  of  the  air,  the  wood  on  the  outside  becomes  of  a 
dark  reddish  brown  color,  while  on  the  inside  it  is  a  pale  yellow  or  orange.  The  form 
in  which  the  coloring  matter  exists  in  the  wood  is  still  a  mooted  question,  however, 
and  some  claim  that  the  hematoxylin  is  present  as  such. 

§  Gardner  has  shown  that  the  ageing  process  in  the  preparation  of  Logwood  chips  is 
not  essential,  as  the  unaged  chips  may  be  used  with  equal  results  if  an  oxidizing  mordant 
is  employed  (chrome  alone  or  chrome  with  sulphuric  acid) .  This  is  on  account  of  the 
fact  that  in  the  fresh  chips  the  coloring  matter  exists  principally  as  hematoxylin,  which 
requires  to  be  o.xidized  in  the  dyeing  to  develop  the  full  advantage  of  the  color;  whereas 
in  the  aged  chips  the  coloring  matter  is  principally  hematine,  and  this  is  most  advan- 
tageously dyed  on  a  reduced  mordant  (chrome  and  tartar).  The  idea  that  ageing  was 
necessary  in  preparing  the  chips  was  no  doubt  a  result  of  the  times  before  an  o.xidizing 
mordant  like  chrome  was  known,  and  when  only  non-oxidizing  mordants  like  copperas 
were  used.  Hummel  has  shown  that  when  dyeing  with  fresh  Logwood  chips  the  addi- 
tion of  chalk  or  calcium  acetate  to  the  dyebath  develops  the  coloring  power  to  a  remark- 
able extent,  and  has  the  effect  almost  as  if  hematine  were  used.  This  is  probably  due 
to  the  formation  of  a  salt  of  the  coloring  matter  with  the  lime. 


472 


USE  OF   LOGWOOD   IX    DYEING 


but  at  the  present  time  it  is  customary  to  carry  tlie  manufacture  of  the 
djTstuff  still  further  and  prepare  an  extract  either  in  the  solid  or  the  liquid 
form.* 

Logwood  is  about  the  only  natural  coloring  matter  which  is  still  exten- 
sively used  (with  the  exception  of  Indigo  and  Quercitron).  Its  principal 
use  at  the  present  time  is  for  the  black  dyemg  of  silk  and  leather;  its  use 
on  cotton  is  decreasing,  and  on  wool  it  is  used  only  for  very  cheap  blacks. 


Fig.  244. — Reel  Dyeing  Machine  for  LogiA^ood. 

This  is  due  to  the  fact  that  there  arc  several  blacks  for  both  wool  and  cotton 
which  are  much  faster  than  Logwood. 

*  The  chipped  or  rasped  Logwood  as  it  occiu-s  in  trade  often  contains  an  abnormal 
amount  of  water,  sometimes  as  high  as  50  per  cent,  while  the  normal  amount  in  well- 
matured  wood  is  only  about  30  per  cent.  In  the  natural  unmatured  wood  the  amount  is 
only  about  14  per  cent.  The  appearance  of  well-matured  chips  is  a  dark  brownish  red 
color,  which  when  dried  assumes  a  greenish  bronze  appearance. 

Log^vood  extract  occurs  in  trade  in  a  liquid  form  of  various  densities,  but  usually 
standing  between  40  and  51°  Tw.  The  specific  gravity,  however,  is  no  guide  as  to  the 
value  of  the  extracts,  as  inferior  extracts  are  often  brought  up  to  a  high  specific  gravity 
by  the  addition  of  glucose,  salt,  or  more  generally,  by  the  addition  of  molasses,  which 
makes  a  convenient,  cheap,  and  difficultly  detectable  adulterant.  Solid  extracts  are 
often  sophisticated  with  salt,  and  sometimes  with  farina  and  various  tannin  extracts. 


REACTIONS  OF  LOGWOOD  473 

In  combination  with  the  various  mordants  Logwood  gives  colors  as 
follows: 

With  iron gray  to  black 

With  copper green-blue  to  black 

With  chromium blue  to  black 

With  aluminium violet-gray. 

With  tin purple 

The  fastness  to  light  of  colors  obtained  with  Logwood  varies  somewhat 
with  the  nature  of  the  mordant  on  which  they  are  dyed.  The  logwood- 
chrome  lake  is  fairly  fast,  but  fades  to  a  greenish  tone;  the  iron  lake  is 
about  equally  fast  and  fades  to  a  gray  tone;  the  tin  and  aluminium  lakes 
are  not  especially  fast,  fading  rather  rapidly  to  a  gray  tone;  the  copper 
lake  is  the  most  permanent  to  light.*  There  are  black  coal-tar  mordant 
dyes  which  are  faster  to  light  than  Logwood;  Diamond  Black,  for  instance, 
together  with  the  black  dyes  of  its  same  general  class,  have  largely  super- 
seded Logwood  for  the  dyeing  of  blacks  on  high-grade  woolen  and  worsted 
fabrics,  especially  those  which  require  an  excellent  fastness  to  light.  In 
former  years,  when  Logwood  blacks  were  principally  employed  for  the 
dyeing  of  men's  suitings  and  overcoat  cloth,  it  was  quite  customary  to 
notice  the  faded  greenish  coat  or  hat ;  but  at  the  present  time  such  a  defect 
is  very  seldom  seen  if  the  fast  coal-tar  black  dyes  have  been  used. 

Logwood  extract  (51°  Tw.)  is  usually  about  three  to  four  times  as  strong 
as  the  chip  Logwood  (aged) .  f     The  former  consists  of  a  mixture  of  hema- 

*  The  fastness  of  Logwood  black  to  light  may  be  increased  by  using  a  fast  red  or  violet 
dyestuff  in  the  Logwood  bath;  the  result  being  that  as  the  Logwood  turns  to  a  greenish 
tone,  the  red  coloring  matter  will  neutralize  this  green,  thus  preserving  the  true  black. 
Alizarine  Red  is  largely  used  for  this  purpose,  taking  the  place  of  the  madder  which  was 
formerly  used.  GaUocyanine,  Archil,  and  the  red-woods  have  also  been  used,  but  as 
they  are  not  as  fast  as  Alizarine  Red,  they  are  not  so  satisfactory,  though  GaUocyanine 
gives  very  good  results,  especially  as  the  black  it  gives  in  connection  with  Logwood  is  of  a 
rich  bloomy  tone. 

t  Logwood  extract  is  usually  made  from  the  unaged  wood,  as  in  the  first  place  the 
hematoxylin  is  much  more  soluble  and  more  readUy  extracted  than  the  hematine,  which  is 
present  in  the  aged  wood.  In  the  second  place,  in  the  process  of  extraction  and  concen- 
tration there  is  always  a  certain  amount  of  unavoidable  oxidation,  and  if  hematine  were 
present  this  might  lead  to  the  destruction  of  considerable  coloring  matter.  Further- 
more, it  is  mostly  required  in  the  preparation  of  Logwood  extracts  to  have  a  low  degree 
of  oxidation.  There  are  two  general  methods  of  extraction;  the  French  method  treats 
the  chips  in  open  pans  with  boiling  water,  whereas  the  American  method  extracts  in  a 
closed  kier  with  steam  under  15  to  30  lbs.  pressure.  The  American  method  gives  a  yield 
about  25  per  cent  greater  than  the  other  process,  but  it  is  said  that  the  extra  amount 
consists  mostly  of  extractive  matters  other  than  coloring  matters,  so  that  the  apparent 
advantage  of  having  a  larger  yield  is  discounted.  It  is  also  claimed  that  the  French 
method  gives  an  extract  which  yields  brighter  and  purer  colors  in  dyeing,  owing  to  the 
presence  of  less  brown  extractive  matters.  A  good  wood  will  yield  by  the  French  process 
about  16  per  cent  of  extractive  matters  and  by  the  American  process  about  20  per  cent. 


474 


USE  OF  LOGWOOD   IN    DYEING 


toxylin  and  hematine,  whereas  the  latter  consists  almost  entirely  of  hema- 
toxylin. According  to  the  degree  of  oxidation  the  extracts  (either  liquid 
or  solid)  are  known  as  "  Logwood  Extract  "  or  as  "  Hematine  Extract." 
The  sohd  hematine  extracts  are  usually  known  as  "  Hematine  Crystals." 
A  good  Logwood  extract  will  show  about  20  per  cent  oxidation ;  that  is  to 
say,  about  20  per  cent  of  the  hematoxylin  has  been  converted  into  hematine. 
On  the  other  hand,  a  good  sample  of  hematine  usually  shows  an  80  per 
cent  oxidation. 

Cheap  grades  of  Logwood  extract  are  frequently  mixed  with  chestnut 
extract  for  cotton  dyeing;    as  this  extract  runs  high  in  tannin,  and  it  is 


//Z77^. 


Fig.  245. — Open  Width  Dyeing  M-achine  for  Log^^'ood.     (Haubold.) 

sometimes  difficult  to  tell  from  a  dyeing  test  that  the  Logwood  is  weaker, 
owing  to  the  tannin  giving  a  black  color  with  the  iron  mordant  used  in  the 
dj'eing  of  the  cotton,  and  also  on  account  of  the  coloring  matter  of  the 
chestnut  extract. 

Hematines  are  made  from  Logwood  extracts  by  air  oxidation  (usually 
blowing  of  air  through  the  extract  until  the  proper  degree  of  oxidation  has 
been  reached.*     Quicker  and  more  complete  oxidation  may  be  obtained 

*  The  bronzy  appearance  to  be  noticed  on  aged  Logr^'ood  chips  is  often  supposed 
to  be  due  to  the  formation  of  hematine;  but  this  is  not  the  case,  as  the  bronzy  appear- 
ance is  due  to  the  presence  of  an  ammonia  compound. 


TESTING  OF  LOGWOOD  475 

by  the  addition  of  sodium  nitrite  or  of  copper  sulphate.  In  this  same  con- 
nection it  may  be  stated  that  in  the  dyeing  of  Logwood  extract  on  the  fiber 
the  addition  of  a  small  amount  (1  per  cent)  of  sodium  nitrite  to  the  bath 
when  the  dyeing  is  almost  completed  will  produce  a  much  fuller  shade 
of  black  with  the  same  quantity  of  Logwood,  Copper  sulphate  may  also 
be  used  in  the  same  manner.* 

In  the  valuation  of  Logwood  chips  and  extracts  (including  also  the 
hematine  extracts)  there  has  always  been  more  or  less  confusion.  This  is 
particularly  true  of  those  who  are  not  familiar  with  the  dyeing  properties 
and  practical  use  in  dyeing  of  the  various  Logwood  products.  But  much  of 
the  same  confusion  also  exists  even  among  the  dyers  themselves.  Thia 
is  chiefly  due  to  the  presence  in  the  Logwood  of  the  two  ingredients,  the 
hematoxyhn  and  the  hematine,  which  behave  differently  in  dyeing,  depend- 
ing on  the  character  of  the  mordant  employed.  A  sample,  for  example, 
rich  in  hematoxylin  and  of  high  color  value,  may  show  up  poorly  if  tested 
against  a  sample  rich  in  hematine  yet  of  lower  color  value  if  dyed  on  a 
reduced  mordant  (of  chrome  and  tartar) .  Furthermore  a  sample  consisting 
mostly  of  hematine  might  be  considered  poor  by  a  dyer  who  is  accus- 
tomed to  using  an  oxidizing  mordant  (of  chrome  alone  or  chrome  with  sul- 
phuric acid),  as  the  oxidizing  mordant  may  cause  overoxidation  of  the 
color  and  the  consequent  production  of  a  pale  shade.  It  is  necessary, 
therefore,  thoroughly  to  understand  the  difference  in  the  nature  and 
behavior  of  the  hematoxylin  and  the  hematine,  and  to  regulate  the  testir.g 
and  comparison  of  samples  accordingly.  The  full  tinctorial  power  of 
the  extract  or  the  wood  may  generally  be  obtained  by  testing  on  wool 
mordanted  w'th  3  per  cent  of  chrome  alone;  whereas  the  tinctorial  power 
due  principally  to  the  hematine  present  may  be  tested  by  dyeing  on  wool 
mordanted  with  3  per  cent  of  chrome  and  4  per  cent  of  tartar. 

The  possible  presence  of  impurities  in  Logwood  extracts  must  also  be 
taken  into  consideration.  In  the  case  of  Logwood  for  cotton  dyeing,  for 
example,  the  addition  of  tannin  (such  as  chestnut  extract)  to  as  much  even 
as  20  per  cent  may  not  cause  a  lower  tinctorial  value  in  the  Logwood  owing 
to  the  fact  that  the  tannin  combines  with  the  iron  mordant  used  in  cotton 
dyeing  to  give  a  black  color  somewhat  similar  to  the  Logwood  itself.  If 
used  in  wool  dyeing,  however,  such  an  extract  would  show  up  much  inferior 
to  one  possessing  the  same  amount  of  actual  Logwood,  but  not  containing 
tannin,  as  here  an  iron  mordant  is  not  used  and  furthermore  the  tannin 
reduces  the  dyeing  power  of  the  wool.  If  the  adulterant,  however,  were 
molasses  or  glucose  such  a  difference  would  not  be  noted  on  the  wool. 

*  According  t©  a  patent  of  Lepetit,  Dollfus  and  Gannser  {Jour.  Soc.  Dyers  and  Col., 
1905,  p.  251),  the  addition  of  15  to  20  per  cent  of  magnesium  sulphate  to  Logwood  extract 
has  the  effect  of  producing  a  much  deeper  black.  The  effect,  however,  is  more  due  to 
the  bluestone  which  is  also  employed  than  to  the  magnesium  sulphate. 


476  USE   OF  LOGWOOD   IX   DYEING 

r   I 

'-3.  Dyeing  on  Wool. — On  wool  Logwood  is  now  almost  entirely  used  on  a 
chrome  mordant,  and  the  color  obtained  is  a  Ijluish  black.  About  15  per 
cent  of  Logwood  extract  is  required  for  the  production  of  full  shades.  To 
neutralize  the  bluish  tone  of  the  straight  Logwood,  it  was  formerly  the  cus- 
tom to  use  some  Fustic  (a  yellow  wood  color)  in  connection  with  the  Log- 
wood. Fustic  is  still  used  in  this  manner,  but  as  it  is  rather  fugitive,  it  is 
better  to  employ  a  faster  mordant  yellow  dyestuff  for  this  purpose.  In 
the  dyeing  of  Logwood  it  is  to  be  noticed  that  an  excess  of  chrome  in  the 
mordanting  bath  is  injurious  to  the  color.  Sometimes  Logwood  black  on 
wool  is  after-chromed  for  the  purpose  of  making  the  color  faster  to  washing 
and  fulling.  Stannous  chloride  is  at  times  added  to  the  dyebath  for  the 
purpose  of  giving  a  violet  tone  to  the  black.  Logwood  extract  is  some- 
times mixed  with  copperas  and  bluestone  and  sold  in  the  form  of  a  paste 
as  a  direct  Logwood  black  for  wool ;  it  is  dissolved  by  adcUng  oxalic  acid  to 
the  bath.*  A  direct  chrome  black  can  also  be  prepared  by  precipitating 
a  solution  of  Logvrood  with  chrome  and  dissolving  the  precipitate  in  oxalic 
acid.  Sometunes  wool  is  firet  dyed  in  the  indigo  vat  to  a  blue,  and  then 
topped  off  with  Log\\'Ood,  giving  a  bluish  black;  this  is  known  as  a 
"  woaded  "  black,  f 

Formerlj'  Log^\•ood  black  was  dj^ed  on  wool  with  an  iron  mordant, 
copperas  being  employed  for  this  purpose.     This  was  previous  to  the 

*  Bonsor's  Fast  Direct  Black  was  a  paste  consisting  of  a  Log^-ood  lake  with  copperas 
and  a  small  amount  of  bluestone.  The  dj'e  is  insoluble  in  water,  but  is  brought  into 
solution  by  the  addition  of  oxalic  acid,  giving  an  amber-brown  solution;  the  amount  of 
oxalic  acid  to  be  added  can  be  determined  only  by  trial  To  dye  the  wool  the  material 
is  simply  boiled  in  the  oxalic  acid  solution  for  about  two  hours,  then  a  small  amount  of 
soda  ash  is  added  to  neutralize  the  acidity  of  the  bath  and  help  to  further  develop  the 
color.  The  bath  may  be  used  continuousl}-  with  additions  of  dye  and  oxalic  acid  as 
required.  Too  much  acid  should  be  avoided,  as  this  retards  the  dyeing  and  gives  thin 
colors.  Many  acid  dj'es  may  be  used  in  the  bath  to  modifj^  the  shade.  A  black  obtained 
in  this  manner  is  quite  fast  to  light.  The  follov/ing  one-bath  process  for  Log^sood  on  wool 
IS  given  bj'  Gardner:  Use  a  bath  containing 

G  to  8  per  cent  of  chrome  alum, 
3  to  4  per  cent  of  o.xalic  acid, 
1  per  cent  of  chalk, 
10  to  25  per  cent  of  Logwood  extract. 

The  dyeing  must  be  carefully  conducted,  as  otherwise  the  color  will  come  up  uneven  or 
speckled  in  appearance.  Other  one-bath  blacks  for  wool  are  as  follows:  Dye  with  a 
mixture  of  15  per  cent  of  Logi^-ood  extract,  G  per  cent  of  ferrous  sulphate  and  3  per  cent 
of  oxalic  acid;  start  the  dyeing  lukewarm  and  gradually  heat  to  boihng.  A  greenish 
shade  of  black  may  be  obtained  by  using  the  following:  15  per  cent  of  Logwood 
extract,  4  per  cent  of  copper  sulphate  and  1  per  cent  of  oxaUc  acid. 

t  The  blue  obtained  by  dyeing  Logwood  in  small  amount  (1  to  5  per  cent)  on  wool 
with  a  chrome  mordant  is  somewhat  similar  in  color  to  Indigo,  but  is  not  nearly  as  fast  to 
light.  During  the  war  when  there  was  a  great  shortage  of  Indigo,  Alizarine  Blues,  and 
other  blue  dj'cs  for  wool,Log^vood  was  used  for  this  purpose  to  a  very  considerable  degree. 


DYEING   WOOL  WITH   LOGWOOD  477 

knowledge  of  chrome  and  its  properties  as  a  mordant.  When  properly- 
dyed,  it  is  said  that  the  copperas  black  on  wool  is  superior  in  many  ways 
to  the  chrome  black,  being  less  liable  to  turn  green  on  exposure  to  light 
and  it  also  gives  the  dyed  cloth  a  softer  or  "  kinder  "  handle,  the  chrome 
mordant  making  it  more  harsh  to  the  feel.  The  copperas  black  was 
usually  dyed  by  after-mordanting,  the  cloth  being  first  boiled  for  one  to  two 
hours  in  a  bath  containing  the  Logwood  decoction  together  with  a  little 
Fustic  for  shading;  then  5  per  cent  of  copperas  and  2  per  cent  of  bluestone 
are  added  to  the  bath  and  the  wool  boiled  for  one  hour  longer.  Or  a  sep- 
arate bath  may  be  used  for  the  mordant.  This  process  was  known  as 
"  saddening."  The  addition  of  the  copper  salt  helps  to  develop  the  full 
color  of  the  Logwood  by  its  catalytic  action  in  the  oxidation  of  the  hema- 
toxylin. It  also  makes  the  color  somewhat  faster  to  light.  If  hematine 
(liquid  or  crystal)  is  used  the  bluestone  is  not  so  essential.* 

Sulphuric  acid  is  usually  employed  as  the  assistant  in  the  chrome  bath, 
and  care  should  be  taken  that  its  amount  should  not  exceed  one-third 
that  of  the  chrome  (usually  3  per  cent  of  chrome  and  1  per  cent  of  sul- 
phuric acid) ,  in  order  to  prevent  dull  colors.  This  use  of  sulphuric  acid  is 
especially  necessary  when  the  Logwood  chips  or  the  unoxidized  Logwood 
extract  are  used.  With  chrome  and  sulphuric  acid,  an  "  oxidizing  "  mor- 
dant is  obtained,  as  it  is  probable  that  the  mordant  consists  of  a  yellowish 
chromate  of  chromium.  This  mordant  in  connection  with  Logwood  oxidizes 
the  hematoxylin  to  hematine  and  thus  utilizes  completely  the  coloring 
matter.  If  the  ordinary  chrome  and  tartar  mordant  is  employed  a  green 
reduced  chromium  oxide  is  obtained  on  the  fiber  which  has  no  oxidizing 
properties;  consequently,  on  dyeing  with  Logwood,  the  color  obtained  is 
chiefly  due  to  the  hematine  combining  with  the  mordant  and  the  hema- 
toxylin is  not  completely  utilized.  This  accounts  for  the  fact  that  different 
dyers  may  obtain  entirely  different  results  with  the  same  lot  of  Logwood 
extract.  In  case  W'here  the  Logwood  extract  used  contains  a  large  amount 
of  hematine,  the  reduced  mordant  of  chrome  and  tartar  may  be  used.     It 

*  Logwood  black  on  wool  obtained  with  a  chrome-copper  mordant,  though  fast  to 
fulling  is  not  so  to  light,  and  is  apt  to  turn  green.  The  chrome  logwood  black  is  fast  to 
fulling  and  rather  faster  to  light  than  the  chrome  copper  black,  but  it  is  more  liable  to 
turn  green.  The  iron  logwood  black  is  faster  to  light  than  either  of  the  foregoing  and 
is  less  apt  to  turn  green,  but  it  is  not  so  fast  to  fulling.  The  best  copper-chrome  black  is 
dyed  by  first  mordanting  with  li  to  2^  per  cent  chrome  and  1  to  2  per  cent  bluestone  and 
§  to  I5  per  cent  sulphuric  acid.  After  mordanting  the  goods  should  be  well  washed  and 
then  freed  from  any  trace  of  chromic  acid  by  means  of  a  cold  bath  of  a  dilute  solution  of 
sodium  hyposulphite.  This  is  very  important,  as  the  presence  of  free  chromic  acid  is 
the  chief  factor  in  the  color  turning  green.  Lactic  acid  or  lactolin  may  be  used  with 
the  mordant  in  place  of  sulphuric  acid.  The  goods  are  next  dyed  as  usual  with  Logwood 
and  Fustic.  By  treatment  with  ferrous  sulphate  after  dyeing,  a  deeper  black  faster  to 
light  is  obtained.    This  black  has  but  a  slight  tendency  to  turn  green  and  is  fast  to  fulling. 


478 


USE  OF  LOGWOOD   IN   DYEING 


is  said  that  this  method  of  dyeing  gives  brighter  and  faster  colors  than  when 
an  oxidizing  mordant  is  used  with  Logwootl;  but  this  is  a  mooted  question, 
and  the  difference  in  the  results  may  depend  on  other  factors. 

Wool  may  also  be  mordanted  previously  to  the  dyeing,  in  which  case 
tartar  is  used  in  connection  with  the  copperas.  Alum  and  bluestone  are 
also  frequently  added  with  the  copperas  to  vary  the  tone.  The  dyebath  is 
prepared  with  Logwood  and  a  little  Fustic  for  shading;  it  is  also  recom- 
mended to  add  a  small  amount  of  calcium  acetate  as  it  increases  the  inten- 
sity of  the  color,  this,  however,  need  be  done  only  in  cases  where  a  very 
soft  water  (free  from  lime  salts)  is  used  in  dyeing.  It  is  also  considered 
beneficial  to  let  the  mordanted  wool  lie  overnight  before  dyeing.     It  is 


Fig.  246. — .Sizing  Mangle  for  Cotton  and  Linen  Pieces.     (Zittauer.) 


probable  that  under  these  circumstances  some  of  the  iron  oxide  is  con- 
verted into  the  higher  oxide  (ferric  oxide),  and  this  acts  as  an  oxidizing 
mordant  with  the  Logwood.  "When  bluestone  is  used  with  the  copperas, 
or  when  hematine  is  employed  in  place  of  the  regular  Logwood  decoction,  it 
cannot  be  seen  what  advantage  the  ageing  niay  have.  In  former  days, 
when  only  the  wood  decoction  was  used  in  the  dj-eing  it  was  always  neces- 
essary  to  have  some  oxidizing  effect  in  order  to  convert  the  hcmatoxj'lin 
into  hematine  so  that  the  full  color  might  be  developed.  This  will  often 
account  for  some  of  the  rather  lengthy  processes  to  be  noted  in  the  old 
recipes  for  the  dyeing  of  Logwood.  Also  many  other  natural  dycwoods 
were  frequently  added  with  the  Logwood  in  varj-ing  amounts  in  order  to 
modify  the  tone  of  the  black  obtained  and  also  to  increase  its  fastness; 
madder,  archil,  and  sumac  were  much  used  for  this  purpose. 


D^'EIXG   COTTON    WITH   LOGWOOD  479 

In  order  to  obtain  a  Logwood  black  wliich  is  perfectly  fast  to  washing 
and  rubbing,  it  must  be  borne  in  mind  that  after  coming  from  the  dyebath 
there  is  always  some  unfixed  dyestuff  in  the  fiber,  which  cannot  be  readily 
removed  by  simple  washing  in  water.  Hence  the  goods  are  given  an 
after-mordanting  treatment  (called  "  back-chroming  ")  in  a  third  bath 
with  a  small  amount  of  chrome  (not  over  1  per  cent)  and  at  a  tempera- 
ture of  about  180°  F.  Especial  attention  must  here  be  drawn  to  the  fact 
that  if  too  much  chrome  is  used  in  this  finishing  bath,  the  black  so  obtained, 
though  fast  to  washing,  will  be  hable  to  turn  green  on  exposure  to  light. 
Instead  of  using  a  back-chroming  bath  for  the  purpose  of  fixing  the  excess 
dyestuff,  copperas  (3  per  cent)  may  be  added  directly  to  the  dyebath  after 
dj-eing.  This  will  give  a  dead  black  and  one  not  so  "  clean  "  as  when 
chrome  is  employed.  In  place  of  copperas,  stannous  chloride  (2  per  cent) 
ma}'  be  used,  which  will  give  a  rich  violet  black. 

Navy  blue  on  wool  is  frequently  dyed  ^^•ith  Logwood  on  a  chrome 
mordant  with  the  addition  of  Indigo  extract  to  the  LogAvood  bath  (also 
some  sulphuric  acid  must  be  added).  Such  a  blue,  however,  is  not  fast 
to  light,  as  it  soon  fades  to  gray. 

4.  Dyeing  on  Cotton. — Logwood  is  chiefly  dyed  on  cotton  in  connection 
with  an  iron  mordant,  "  nitrate  of  iron  "  being  principally  used.  The 
iron  salt  is  genei'ally  fixed  on  the  cotton  by  tannm  preliminary  to  dyeing, 
but  at  times  the  fixation  of  the  iron  is  accomplished  by  the  tannin  nat- 
urally present  in  the  Logwood  extract.  As  the  iron  mordant  gives  a  brown- 
ish or  rusty  black,  it  is  advisable  to  chrome  the  color  obtained  to  produce  a 
clearer  and  more  desirable  black.  The  development  of  the  rusty  appear- 
ance on  an  iron-logwood  black  on  cotton  may  also  be  prevented  more  or 
less  by  soaping  the  dyed  color.  By  the  addition  of  bluestone  to  the  dye- 
bath the  color  is  also  said  to  be  improved  in  appearance. 

By  using  a  tannin  and  iron  mordant  wliich  develops  a  gi-ay  to  black 
color  itself,  less  Logwood  is  required  than  when  an  iron  mordant  alone  is 
used.  Logwood  extracts  used  for  the  dyeing  of  cotton  usually  have  con- 
siderable tannin  in  them,  as  this  is  beneficial  in  fixing  the  iron ;  Logwood 
extracts  for  wool  dyeing,  on  the  other  hand,  should  contain  but  little 
tannin,  as  tanned  wool  becomes  less  absorptive  of  the  dyestuff.  The 
amount  of  tannin  in  the  extract  is  regulated  by  the  method  of  extraction 
of  the  coloring  matter  from  the  wood.  The  better  blacks  are  dj-ed  on 
cotton  by  first  steeping  in  tannin  (sumac,  myrabolams,  etc.),  fixing  with 
''  nitrate  of  iron,"  giving  a  bath  of  lime  water  (to  neutralize  the  acid  and 
further  fix  the  iron),  dyeing  with  Logwood  and  Fustic,  then  "  saddening  " 
in  the  dj-ebath  with  2  per  cent  of  copperas,  and  finally  finishing  off  bj-  soap- 
ing. A  cheap  method  for  the  dj-cing  of  piece-goods  is  to  pad  the  cloth  with 
pjTolignite  of  iron,  dry,  give  a  bath  with  lime  water,  and  dj'-e  with  Log- 
wood.    A  method  for  the  dyeing  of  cotton-warp  unions  is  to  pad  with 


480 


USE   OF  LOGWOOD   IN   DYEING 


tannin,  then  pass  through  a  Ixath  of  copper  sulphate,  and  finally  dye  with 
Logwood. 

A  chrome  Logwood  black  may  ho  dyed  in  one  bath  on  cotton  in  the  fol- 
lowing manner:  Dissolve  1^  lbs.  chrome  in  a  small  amount  of  water, 
mix  with  a  solution  of  15  lbs.  of  Logwood  extract,  and  then  add  3^  lbs. 
hj^drochloric  acid.  Start  the  dyeing  cold  and  gradually  raise  the  bath 
to  a  boil.  The  cotton  at  first  will  acquire  a  deep  indigo  blue  color  which 
becomes  a  bluish  black  on  washing  with  calcareous  water  (Hummel). 
Another  one-bath  method  is  to  use  20  lbs.  of  solid  Logwood  extract,  4  lbs. 
of  bluestone,  and  4  lbs.  soda  ash.  Heat  to  180°  F.  and  pass  the  cotton 
through  rather  rapidly,  then  ''  smother  "  for  five  to  six  hours  to  allow  to 


1 


Fig.  247. — Railway  Sewing  and  Rolling  Machine  for  Sewing  Pieces  to  Make  a  Con- 
tinuous Roll.     (Curtis  &  Marble.) 


oxidize.  In  order  to  get  a  good  black  it  is  necessary  to  repeat  the  opera- 
tions one  or  more  times.  This  black  is  rather  expensive  but  stands  fulling 
with  soap  very  well. 

A  Logwood  black  for  loose  cotton  to  l)e  fast  to  fulling  is  as  follows 
(Hummel) ; 

Wet  out  the  cotton  well  in  ])oiling  water,  then  l)oil  in  a  strong  solution 
of  about  30  per  cent  of  solid  Logwood  extract,  drain,  and  allow  it  to  lie 
exposed  to  the  air  for  some  time ;  complete  the  oxidation  thus  begun  by 
working  it  one  hour  in  a  cold  solution  of  8  per  cent  of  bichromate  of  potash 
and  6  per  cent  of  copper  sulphate;  wash  and  complete  the  dyeing  in  a 
bath  containing  10  per  cent  of  Logwood  extract;  enter  the  cotton  cold 
and  raise  the  temperature  gradually  to  the  boiling  point.  Wash,  soap,  and 
dry. 


DYEING   SILK   WITH   LOGWOOD  481 

In  the  first  bath  the  cotton  shnply  absorbs  the  coloring  matter  of  the 
Logwood;  in  the  second  this  is  oxidized,  and  at  the  same  time  combined 
with  a  sufficient  amount  of  the  mordant,  copper,  and  chromic  oxide,  to 
enable  it  to  take  up  still  more  coloring  matter  in  the  third  bath.  The 
first  Logwood  bath  is  analogous  to  the  tannin  bath  alluded  to  in  a  previous 
process. 

X  5.  Dyeing  on  Silk. — Logwood  is  still  used  extensively  for  the  black 
d>Wng  of  silk,  both  unweighted  and  weighted.  It  is  used  in  connection 
with  a  tannin-iron  mordant,  the  tannin  employed  usually  being  cutch. 
Logwood  seems  to  make  the  silk  fiber  opaque,  which  is  a  necessary  condi- 
tion for  the  production  of  a  full  deep  black;  the  coal-tar  blacks,  as  a  rule,  do 
not  make  the  silk  sufficiently  opaque.* 

Logwood  black  on  silk  is  not  only  dyed  for  the  color,  but  also  for 
the  purpose  of  weighting  the  silk.  This  is  accomplished  by  using  a  heavy 
mordant  of  tannin  and  iron  in  connection  with  the  Logwood.  The  weight- 
ing is  usually  about  100  per  cent,  though  it  frequently  ranges  up  to  as  high 
as  400  per  cent.  By  alternate  and  successive  treatments  of  the  silk  with 
solutions  of  tannin  (cutch,  gambier,  chestnut  extract,  etc.)  and  iron  salts 
(pyrolignite  of  iron,  "  nitrate  "  of  iron,  yellow  prussiate)  a  heavy  deposit 
of  iron  tannate  can  be  fixed  in  the  fiber.  In  sufficient  amount  this  iron 
tannate  alone  would  furnish  a  black  color  (and,  in  fact,  this  was  the  man- 
ner in  which  black  was  dyed  on  silk  in  ancient  times)  on  silk  but  it  gives  a 
rather  unpleasant  and  harsh  shade;  whereas  by  dyeing  with  Logwood,  a 
pleasing  bloomy  shade  of  black  is  obtained. 

The  number  of  various  recipes  recommended  for  dyeing  silk  black 
with  Logwood  is  legion,  depending  upon  the  character  of  fiber  (whether 
completely  boiled-off  or  not),  the  tone  of  color  desired,  and  the  degree 
of  weighting  required.  The  general  outline  of  the  process,  however,  is  to 
first  steep  the  silk  for  several  hours  in  a  rather  concentrated  (10  to  15°  Tw.) 
solution  of  gambier  or  chestnut  extract  at  120°  F. ;  then  steep  in  a  solution 
of  p>Tolignite  of  iron  at  12  to  15°  Tw.  at  140°  F.  Squeeze  and  expose 
to  the  air  for  one  or  two  hours,  then  wash.  One  such  treatment  will 
increase  the  weight  of  the  silk  about  20  to  30  per  cent.     Higher  degrees  of 

*  Logwood  is  especially  valuable  in  the  black  dyeing  of  silk,  because  it  renders  the 
fiber  opaque  and  thus  produces  a  full  and  brilliant  black.  This  is  probably  due  to  the 
pigment  nature  of  the  color-lake  and  its  combination  with  the  metallic  mordants  in  the 
fiber.  The  various  coal-tar  black  dyes  on  silk  nearly  all  have  a  slaty  faded  appearance 
when  their  color  is  compared  with  a  Logwood  black.  This  is  by  reason  of  the  silk  fiber 
being  so  translucent  that  the  full  black  color  is  diluted  with  an  excess  of  transmitted 
light.  With  the  exception  of  Logwood,  however,  there  is  perhaps  no  branch  of  dyeing 
in  which  the  natural  vegetable  dyes  are  now  used  to  a  lesser  extent  than  in  that  of  silk 
dyeing.  The  very  nature  of  the  sLlk  fiber  militates  against  the  use  of  dyestuffs  requiring 
metallic  mordants  and  severe  and  complicated  processes  of  dyeing.  Even  Indigo  is  but 
Little  used  in  the  dyeing  of  silk  on  account  of  the  dyevat  containing  lime,  and  the  treat- 
ment being  injurious  to  the  softness  and  luster  of  the  fiber. 


482  USE  OF  LOGWOOD  IX   DYEING 

weighting  are  obtained  by  repeating  the  treatments  in  the  tannin  and  iron 
liquors.  Nitrate  of  iron  may  also  be  used.  A  treatment  with  yellow 
prussiate  of  potash  is  at  times  given  which  not  only  adds  weight,  but  also 
gives  a  blue  color  (Prussian  Blue)  on  the  fiber,  which  is  beneficial  to  the 
appearance  of  the  ultimate  color.  After  the  mordantmg  has  been  carried 
to  the  desired  point  the  silk  is  washed  and  dyed  with  Log\N-ood  extract 
together  with  a  little  Fustic  (depending  on  the  shade  desired) .  The  dye- 
bath  is  usually  not  rmi  at  over  160°  F.  temperature.  After  dyeing  the  silk 
is  generally  aged  by  exposure  to  the  air  for  an  hour,  it  should  then  be 
soaped,  adding  to  the  soap  bath  a  small  amount  of  oil  (2  to  4  per  cent)  for 
the  purpose  of  softening  and  brightening  the  fiber. 

Black  silks  that  are  not  weighted  are  known  as  "  pure  dye  "  black. 
Such  a  color  is  usually  produced  by  first  treating  the  silk  in  a  bath  at 
160°  F.  with  Logwood  extract  (15  per  cent) ;  Fustic  (5  per  cent) ;  copperas 
(5  per  cent)  and  copper  acetate  (3  per  cent).  Allow  to  age  in  the  air  for 
one  hour  and  then  dj-e  again  in  a  fresh  bath  with  15  per  cent  of  Logwood 
extract  and  15  per  cent  of  soap  for  one  hour  at  160°  F,  In  the  case  of 
silk  for  pile  fabrics  (plushes,  etc.),  where  it  is  desired  to  have  a  blue  over- 
cast, the  silk  may  be  mordanted  with  alimi  and  dyed  without  the  use  of 
Fustic.  Sometimes  Logwood  black  is  dj-ed  on  raw  silk  which  is  to  be  used 
for  pile  fabrics  or  for  the  backhig  of  satins,  etc.,  and  it  is  desirable  not  to 
remove  any  more  of  the  silk  gum  than  necessary.  In  this  case  the  tem- 
perature of  the  baths  should  not  go  over  140°  F,  and  soaping  should  be 
omitted. 

6.  Reactions  of  Logwood. — A  solution  of  Logwood  according  to  its 
strength,  possesses  an  orange-j^ellow  to  a  dark  reddish  brown  color.  It 
gives  the  following  characteristic  reactions: 

Dilute  hydrochloric  acid. — Solution  becomes  paler. 

Strong  hydrochloric  acid. — Blood  red  color,  becoming  orange-yellow  on  dilution. 

Sulphuric  acid  gives  the  same  reactions  as  the  above. 

Sodium  carbonate. — Purple  color,  becoming  blue  and  then  brown. 

Sodium  hydrate  gives  same  reaction  as  above. 

A7nmonia. — Deep  reddish  purple,  quickly  turning  brown. 

Lime  water. — Violet-black  precipitate. 

Alum  solution. — Rich  plum  color  slowl}'  developing. 

Lead  acetate. — Dark  violet  precipitate. 

Basic  acetate  of  lead. — Bluish  black  i)rpcipitate. 

Ferrous  sulphate. — Violet-black  precipitate. 

Ferric  sulphate. — Same,  but  redder. 

Copper  sulphate. — Dark  red  precipitate,  becoming  violet. 

Stannous  chloride. — Reddish  violet  precipitate. 

Silver  nitrate. — Yellowish  brown  precipitate. 

Potassium  bichromate. — Black  color  slowly  developing,  on  boiUng  a  black  precipitate. 

^7.  Detection  of  Logwood  on  the  Fiber, — If  a  sample  of  fabric  dyed  with 
Logwood  on  a  chrome  mordant  is  thoroughly  ignited  to  a  complete  ash  the 


DETECTION  OF  LOGWOOD 


483 


color  of  the  residue  should  be  yellowish  or  brownish  green.  On  fusing 
with  a  Uttle  potassium  chlorate  a  bright  yellow  mass  will  be  obtained;  on 
dissolving  this  in  water  and  adding  a  little  acetic  acid  and  lead  acetate 
solution,  a  bright  yellow  precipitate  of  lead  chromate  will  be  formed. 
Chrome-mordanted  Logwood  will  also  give  the  following  tests : 

Concentrated  hydrochloric  acid — I'eddish  violet  color,  slowly  forming. 
Concentrated  sulphuric  acid — olive-brown  color  becoming  yellow  on  dilution. 
Caustic  soda  (10  per  cent) — violet  color,  slowly  forming. 
Concentrated  ammonia — little  action,  slowly  violet. 
Stannous  chloride  solution — reddish  violet. 


Fig.  248. — Rotary  Pressing  Machine. 


These  tests  should  all  be  made  cold  and  most  conveniently  in  small  porce- 
lain dishes  in  order  that  the  developed  color  may  be  readily  seen. 

Logwood  dyed  on  an  iron  mordant  when  ignited  to  an  ash  gives  a  red- 
dish brown  residue;  on  dissolving  this  in  hydrochloric  acid  and  adding  a 
few  drops  of  potassium  ferrocyanide  solution  a  blue  color  is  produced,  con- 
firming the  presence  of  iron.  When  the  dyed  cloth  is  tested  with  above- 
mentioned  reagents  the  color  is  more  crimson  and  more  easily  extracted 
with  hydrochloric  acid  than  when  a  chrome  mordant  is  in  question;  also 
with  caustic  soda  the  color  is  more  rapidly  developed,  while  with  stannous 
chloride  the  color  is  light  red,  otherwise  the  tests  are  the  same. 

Boiling  alcohol  has  no  effect  on  a  dyed  sample  of  Logwood,  and  the 
same  is  true  of  a  boiling  solution  of  soap  or  a  dilute  (|  per  cent)  solution  of 
soda  ash.  When  boiled  with  dilute  hydrochloric  or  sulphuric  acid  the 
color  is  partially  removed  and  the  solution  becomes  red,  the  fiber  being  left 


484  USE  OF  LOGWOOD   IX   DYEING 

a  purplish  color.  Caustic  soda  in  excess  addod  to  the  acid  solution  turns  it 
a  violet  color,  which  gradually  disappears  with  the  formation  of  a  brown 
precipitate.  If  this  test  is  made  with  Logwood  black  containing  AUzarine, 
the  alkaline  solution  remains  purple  after  the  Logwood  has  been  precip- 
itated, and  on  adding  dilute  acid,  the  purple,  if  due  to  Alizarine,  will  turn 
a  deep  yellow.* 

8.  Experimental.  Exp.  166.  General  Method  of  Dyeing  Logwood  on  Wool. — 
Mordant  four  test  skeins  of  woolen  yarn  in  the  usual  manner  with  3  per  cent  of  chrome 
and  1  per  cent  of  sulphuric  acid;  wash  well.  Dye  the  first  skein  in  a  bath  containing 
2  per  cent  of  Logwood  extract  (solid);  enter  at  140°  F.,  gradually  raise  to  the  boil,  and 
dye  at  that  temperature  for  three-quarters  of  an  hour,  then  wash  well  and  dry.  Dj^e  the 
second  skein  in  a  bath  containing  5  per  cent  of  Logwood  extract  in  the  same  manner. 
Dye  the  third  skein  in  the  same  way  with  15  per  cent  of  Logwood  ex-tract.  The  lower 
percentages  of  Logwood  give  bluish  shades  on  a  chrome  mordant,  which  deepen  into  a 
bluish  black  in  the  heavy  percentage.  Dye  the  fourth  skein  in  a  bath  containing 
a  decoction  made  by  boiling  50  per  cent  of  chipped  Logwood  in  300  cc.  of  water.  Notice 
that  at  first  the  dj'ebath  is  of  a  reddish  color,  but  that  the  black  develops  on  boiling. 
Logu'ood  extract  requires  an  oxidizing  mordant  (clirome  and  sulphuric  acid,  which 
gives  chromic  acid  on  the  fiber)  in  order  property  to  develop  the  color,  as  it  is  necessary 
to  oxidize  the  hematoxylin  to  hematine  to  form  the  color-lake.  To  show  the  difference 
in  the  use  of  an  oxidizing  and  reduced  mordant,  mordant  one  skein  with  chrome  and 
sulphuric  acid  and  another  chrome  and  tartar;  then  dye  both  with  5  per  cent  of  Logwood 
extract. 

Exp.  167.  Effect  of  Over-chroming. — Mordant  a  test  skein  of  woolen  yarn  with  10 
per  cent  of  chrome  and  5  per  cent  of  sulphuric  acid  in  the  usual  manner;  wash  well,  and 
dye  in  the  manner  described  above  with  15  per  cent  of  Logwood  extract.  It  wiU  be  found 
that  only  a  gray  color  is  produced;  this  is  the  result  of  employing  too  much  chrome, 
whereby  the  fiber  becomes  oxidized  and  loses  its  affinity  for  the  dyestuff .  It  maj'  also  be 
probable  that  the  excess  of  chrome  has  some  injurious  action  on  the  Logwood  itself. 

Exp.  168  Dyeing  with  Hematine. — This  requires  the  use  of  a  reduced  mordant 
(i.e.,  chrome  and  tartar  instead  of  chrome  and  sulphuric  acid)  as  hematine  is  already 
oxidized.  Mordant  two  test  skeins  of  woolen  yarn  with  3  per  cent  of  chrome  and  4 
per  cent  of  tartar.     Dye  the  first  in  a  bath  containing  2  per  cent  of  hematine  crystals 

*  LogAA'ood  when  dj^ed  in  connection  with  Alizarine  Blue  or  Gallocyanine,  may  be 
detected  in  the  following  manner:  Treat  the  dyed  sample  with  cold  concentrated  sul- 
phuric acid;  if  dyed  with  Logwood,  as  already  stated,  a  brownish  red  solution  will  be 
obtained  which  becomes  yellow  on  dilution  with  water;  Alizarine  Blue  gives  a  deep 
violet-blue  solution,  becoming  red-violet  on  dilution;  Gallocyanine  gives  a  violet 
solution  becoming  redder  on  dilution;  Indigo  gives  a  green  solution  which  turns  blue, 
and  remains  blue  on  dilution.  With  a  mixture  of  Indigo  and  Logwood  the  solution  is 
green  after  adding  sulphuric  acid  and  diluting  with  water,  but  after  filtering  the  solution 
several  times,  the  Indigo  is  retained  on  the  filter,  and  the  yellow  of  the  Logwood  only  is 
obtained  in  the  filtrate.  The  delicate  pink  given  by  small  amounts  of  Alizarine  Blue  or 
Gallocyanine,  becomes  red,  orange,  to  orange-yellow  in  the  presence  of  Logu'ood,  depend- 
ing upon  the  amount  of  the  latter  present.  Logwood  may  at  once  be  detected  in  an 
Indigo-tlyed  fabric  by  boiling  with  a  5  per  cent  solution  of  sulphuric  acid,  which  removes 
the  Logwood,  giving  a  reddish  solution,  and  leaves  the  Indigo  on  the  fiber.  Material 
dyed  with  Indigo  and  Logwood  colors  hydrochloric  acid  red  and  a  10  per  cent  solution 
of  caustic  soda  violet,  whereas  pure  Indigo  yields  no  color  with  either  solution. 


EXPERIMENTAL  STUDIES  485 

and  the  second  with  6  per  cent  of  Hematine  crystals,  compare  these  dyeings  with  those 
of  Logwood  extract. 

Exp.  169.  Shading  with  Fustic. — Mordant  a  test  skein  of  wool  with  3  per  cent  of 
chrome  and  2  per  cent  of  sulphuric  acid,  rinse  and  dye  with  15  per  cent  Logwood  extract 
(paste)  and  5  per  cent  Fustic  extract  (paste) .  It  will  be  found  that  the  black  so  obtained 
has  not  the  bluish  cast  of  the  preceding,  but  is  more  on  the  order  of  a  dead  black,  the 
yellow  color  of  the  Fustic  having  neutralized  the  blue  tone  of  the  Logwood. 

Exp.  170.  Shading  Logwood  with  Alizarine  Yellow. — This  is  for  the  purpose  of 
obtaining  a  deep  black  without  the  bluish  tone  of  the  straight  Logwood  black.  Mordant 
a  skein  of  woolen  yarn  in  the  usual  manner  with  3  per  cent  of  chrome  and  4  per  cent  of 
tartar;  wash,  and  dye  in  a  bath  containing  15  per  cent  of  Logwood  extract  and  j  per  cent 
of  Alizarine  Yellow  AW.  Enter  at  100°  F.,  gradually  raise  to  the  boil,  and  dye  at  that 
temperature  for  three-quarters  of  an  hour;  then  wash  well  and  dry.  Compare  the  color 
of  this  skein  with  that  dyed  with  Logwood  alone. 

Exp.  171.  After-chroming  Logwood  on  Wool.^This  method  is  practiced  in  order  to 
give  a  black  which  is  faster  to  washing  and  fulling,  the  result  probably  being  that  the 
outermost  layer  of  Logwood  in  the  dyeing  of  the  wool  is  only  incompletely  fixed  by 
the  underlying  mordant,  and  the  after-mordanting  sarves  to  more  thoroughly  fix  this 
layer  and  hence  furnishes  faster  colors  than  would  otherwise  be  the  case.  Mordant 
a  test  skein  of  wool  in  the  usual  manner  with  chrome,  dye  with  15  per  cent  of  Logwood 
extract  (paste),  and  finally  finish  off  in  a  bath  containing  1  per  cent  of  chrome;  work 
for  a  half  hour  at  1S0°  F.,  and  then  wash  well.  If  too  much  chrome  is  used  in  the  last 
bath  the  black  will  be  apt  to  turn  green  on  exposure.  Instead  of  using  chrome,  other 
salts  may  be  employed  for  the  after-fixing,  such  as :  (a)  Mordant  a  test  skein  of  wool 
with  chrome  in  the  usual  manner,  dye  with  15  per  cent  of  Logwood  extract  (paste),  and 
fix  by  adding  to  the  bath  3  per  cent  copperas,  work  for  one-quarter  hour  longer.  A 
dead  black  is  obtained  in  this  manner  and  the  excess  of  coloring  matter  is  fixed,  but  the 
color  has  not  the  same  purity  or  cleanness  as  the  foregoing.  (6)  Mordant  a  test  skein 
of  wool  with  cnrome  in  the  usual  manner,  dye  with  15  per  cent  of  Logwood  extract 
(paste),  and  then  add  to  the  dyebath  2  per  cent  stannous  chloride,  and  work  for  one- 
quarter  hour  longer.     This  fixes  the  coloring  matter  and  gives  a  rich  violet  black. 

Exp.  172.  Logwood  Black  on  Wool  with  Iron  Mordant. — This  method  of  producing 
blacks  on  wool  was  formerly  very  largely  used,  but  at  the  present  time  it  has  mostly 
given  place  to  the  use  of  Alizarine  and  other  mordant  blacks,  such  for  instance  as  Dia- 
mond Black,  (a)  Mordant  a  test  skein  of  wool  in  a  bath  containing  S  per  cent  copperas 
and  10  per  cent  tartar;  enter  at  140°  F.,  gradually  bring  to  the  boil  and  continue  for 
one-half  hour.  Wash  well  and  dye  with  2  per  cent  Logwood  extract  (paste) .  Repeat 
the  test,  using  5  per  cent,  10  per  cent,  and  15  per  cent  of  Log^'ood  extract  (paste).  With 
small  amounts  of  Logwood  only  slaty  blue  or  bluish  gray  colors  are  produced,  but  with 
the  last  test  a  full  black  color  should  be  obtained.  Usually  alum  and  bluestone  are 
also  added  to  the  mordant  bath,  in  order  to  prevent  the  rather  rusty  appearance  which 
the  iron  salt  alone  imparts. 

(6)  Mordant  a  test  skein  of  wool  with  5  per  cent  copperas,  2  per  cent  bluestone,  and 
2  per  cent  alum,  and  10  per  cent  tartar.  Dye  with  15  per  cent  Logwood  extract.  In 
order  to  produce  a  fuller  shade  of  dead  black,  a  little  Fustic  is  sometimes  added  to  the 
dyebath  as  in  the  test  with  chrome  blacks.  The  copperas  black  with  Logwood  is  said 
to  be  superior  to  the  chrome  black,  as  it  is  less  liable  to  turn  green  and  the  handle  of 
the  goods  remains  softer.  Instead  of  mordanting  before  dyeing,  the  process  may  be 
reversed  and  the  copperas  bath  may  be  used  last.  This  method  is  said  to  give  better 
results  than  the  foregoing. 

(c)  Dye  a  test  skein  of  wool  in  a  bath  containing  15  per  cent  of  Logwood  extract  and 
2  per  cent  of  Fustic  extract,  add  5  per  cent  copperas  and  2  per  cent  bluestone  to  the  dye-i 


486 


USE  OF   LOGWOOD   IN   DYEING 


bath,  and  boil  for  three-quarters  of  an  hour  longer.  This  method  is  known  as  the  "  sad- 
dening "  process.  The  addition  of  bluestone  appears  to  make  the  black  faster  to  light, 
and  it  is  also  probable  that  it  assists  in  the  development  of  the  black  by  reason  of  its 
oxidizing  action  on  the  Logwood.  The  wool  must  not  be  washed  between  the  opera- 
tions of  dyeing  and  mordanting,  as  a  large  part  of  the  dyestuff  would  be  removed,  as 
it  is  not  yet  fixed  in  the  fiber. 

The  addition  of  a  small  amount  of  calcium  acetate  to  the  dyebath  with  Logwood  is 
said  to  be  beneficial,  in  that  it  gives  a  greater  intensity  of  color;  the  addition  of  this  salt, 
however,  is  only  necessary  where  the  water  employed  is  deficient  in  lime  salts.  Better 
results  are  also  obtained  when  the  mordanted  wool  is  allowed  to  "  age  "  for  several 
hours  before  being  dyed;  this  is  probably  due  to  the  oxidation  of  the  ferrous  oxide  in 
the  fiber  to  the  ferric  condition,  and  this  no  longer  exerts  a  reducing  action  on  the  Log- 
wood. 


Fig.  249. — Hydraulic  Mangle.     (Weisbach.) 


Exp.  173.  Direct  Chrome  Black  for  Wool. — By  boiling  a  solution  of  Logwood  with 

potassium  bichromate  a  black  precipitate  is  obtained  which  may  be  used  by  the  dyer  as 
a  direct  chrome  black.  The  paste  is  mixed  with  water  and  dissolved  in  oxalic  acid, 
and  the  wool  is  then  dyed  in  this  solution.  The  results  obtained  by  this  direct  black, 
however,  are  not  as  good  as  those  produced  with  the  preceding  direct  dyestuff  prepared 
from  iron  and  copper  salts.  Take  10  grams  of  Logis'ood  extract  (paste),  boil  up  with  a 
little  water,  and  add  3  grams  of  potassium  bichromate  previously  dissolved  in  a  little 
water;  boil  the  mixture  for  one-half  hour;  filter.  With  a  portion  of  the  precipitate  so 
obtained,  prepare  a  dyebath  by  mixing  the  pasty  precipitate  with  water  and  adding 
sufficient  oxalic  acid  to  dissolve  it.  Dye  a  test  skein  of  wool  in  this  bath  at  the  boil 
for  one  hour. 

Exp.  174.  Woaded  Black  on  Wool. — This  is  tl:c  name  apjilied  to  a  black  obtained 
by  first  dyeing  the  wool  a  blue  in  the  Indigo  vat,  then  topping  off  with  Logwood,  either 
with  the  copperas  or  chrome  method.  Take  a  test  skein  of  wool  which  has  been  dyed 
a  medium  shade  of  blue  in  the  Indigo  vat,  mordant  it  in  the  usual  manner  with  2  per  cent 


EXPERIMENTAL  STUDIES  487 

of  chrome  and  4  per  cent  of  tartar;  then  dye  with  10  per  cent  Logwood  extract  (paste). 
The  purpose  of  the  Indigo  bottom  is  to  give  a  richer  and  bloomier  black,  and  one  which 
is  faster  to  light.  Also,  Logwood  black  on  exposure  is  liable  to  become  somewhat  rusty 
in  appearance,  whereas  if  dyed  over  an  Indigo  blue,  this  rusty  appearance  is  prevented. 
The  mordanting  of  the  wool  with  chrome  must  be  done  without  the  use  of  acid,  other- 
wise the  Indigo  will  be  oxidized  and  destroyed,  and  even  if  carried  out  in  the  manner 
given  above,  it  is  very  probable  that  a  considerable  amount  of  Indigo  is  removed  from 
the  wool.  If  only  a  small  amount  of  Indigo  is  used  in  the  first  \Aace  the  chances  are 
that  scarce!}'  any  Indigo  will  be  left  in  the  fiber,  consequently  its  effect  will  be  negligible. 
Sometimes  the  Indigo  is  not  dyed  on  the  fiber  until  after  the  chroming,  in  order  to 
prevent  loss  of  Indigo.  Although  woaded  blacks  have  a  good  name,  it  is  doubt- 
ful if  they  are  as  good  as  blacks  obtained  by  the  use  of  Logwood,  Fustic,  and 
Alizarine. 

Exp.  175.  Logwood  with  Aluminium  Mordant. — Logw-ood  in  connection  with  an 
aluminium  mordant  gives  a  violet-blue  color.  Mordant  a  test  skein  of  wool  with  6 
per  cent  alum  and  6  per  cent  tartar  in  the  usual  manner;  wash  well  and  dye  with  2  per 
cent  Logwood  extract  (paste).  Repeat  the  e\-periment,  using  5  per  cent,  8  per  cent,  10 
per  cent,  and  finally  15  per  cent  of  Logwood  extract.  Unless  the  water  of  the  dyebath 
contains  considerable  lime,  there  should  be  added  4  per  cent  calcium  acetate,  as  this  will 
give  brighter  shades.  Water  Blue  may  be  added  to  the  mordant  bath  in  order  to  brighten 
the  ultimate  color. 

Exp.  176.  Logwood  with  Tin  Mordant. — Logwood  in  connection  with  a  tin  mordant 
on  wool  gives  a  purple.  The  color  is  seldom  used  as  a  self  shade,  but  Logwood  blacks 
are  frequently  given  a  purplish  tone  by  the  addition  of  a  small  amount  of  starmous 
chloride.  Mordant  a  test  skein  of  wool  in  the  usual  manner  with  4  per  cent  stannous 
chloride  and  4  per  cent  o.xalic  acid;  wash  well,  and  dye  with  2  per  cent  Logwood  extract. 
Also  dye  skeins  mordanted  in  the  same  manner  with  5  per  cent,  8  per  cent,  10  per  cent, 
and  15  per  cent  of  Logwood  extract.  This  color  is  not  especially  fast,  and  the  tin  mor- 
dant also  imparts  a  harsh  feel  to  the  wool. 

Exp.  177.  Logwood  Black  on  Cotton  with  an  Iron  Mordant. — The  principal  use  of 
Logwood  on  cotton  is  for  the  production  of  blacks  and  grays  in  connection  with  an  iron 
mordant.  The  chief  salt  used  for  this  purpose  is  the  so-called  "  nitrate  of  iron."  The 
mordant  is  fixed  by  means  of  tannin.  Steep  a  test  skein  of  cotton  yarn  in  a  bath  con- 
taining 4  per  cent  of  tannic  acid;  enter  at  180°  F.,  work  for  fifteen  minutes  at  that  tem- 
perature, then  allow  to  steep  under  the  liquor  without  further  heating  for  one  hour. 
Squeeze,  and  pass  through  a  bath  of  nitrate  of  iron  at  4°  Tw.  for  fifteen  minutes  cold; 
then  squeeze  and  pass  through  a  weak  bath  of  lime-water  cold  for  ten  minutes,  and 
finally  wash  well.  The  tannate  of  iron  thus  formed  on  the  fiber  imparts  to  the  cotton  a 
dark  gray  color.  Now  dye  the  skein  in  a  bath  containing  15  per  cent  of  Logwood  extract 
(solid)  and  2  per  cent  soda  ash;  enter  at  160°  F.,  gradually  raise  to  the  boil,  and  dye 
at  that  temperature  for  three-quarters  of  an  hour.     Wash  well  and  dry. 

Exp.  178.  To  Obtain  a  Faster  and  Clearer  Black. — Mordant  a  test  skein  of  cotton 
yarn  in  the  same  manner  as  above  with  4  per  cent  of  tannic  acid,  and  then  fix  by  passing 
through  the  baths  of  nitrate  of  iron  and  lime-water.  Then  dye  as  before  with  15  per 
cent  of  Logwood  extract.  After  dyeing,  work  the  skein  in  a  bath  containing  1  per  cent 
of  chrome;  enter  at  180°  F.,  work  for  fifteen  minutes  at  that  temperature,then  squeeze 
and  wash  well,  and  finally  soap  off  in  a  warm  dilute  soap  bath.  Instead  of  using  the 
chrome  bath  the  dyed  material  may  be  passed  back  into  the  nitrate  of  iron  bath.  This 
after-treatment  and  scouring  with  soap  have  the  effect  of  preventing  the  rusty  appear- 
ance liable  to  develop  when  Logwood  is  dyed  with  an  iron  mordant.  It  is  sometimes 
the  practice  to  pass  the  cotton  through  a  weak  lime  bath  after  coming  from  the  tannin 
bath  and  before  entering  the  bath  of  nitrate  of  iron;  this  causes  the  formation  of  tannate 


488 


USE  OF   LOGWOOD   IN    DYEIXG 


of  lime,  and  prevents  a  large  amount  of  the  unfixed  tannin  from  passing  into  the  iron 
bath  and  precipitatinj?  tannate  of  iron. 

Exp.  179.  Dyeing  Logwood  without  Tannin. — Cotton  may  also  be  dyed  with  iron 
and  Logwood  without  the  intervention  of  tannin.  Steep  a  test  skein  of  cotton  yarn  in  a 
bath  containing  nitrate  of  iron  at  8°  Tw.,  cold,  for  one-half  hour;  squeeze  and  work  for 
fifteen  minutes  in  a  bath  containing  5  grams  of  soda  ash  at  140°  F.  This  causes  a  pre- 
cipitation of  ferric  oxide  or  iron  buff  in  the  fiber.  Wash,  and  dye  as  previously  described 
in  experiment  1  with  15  per  cent  of  Log\v()od  extract. 

Exp.  180.  Logwood  on  Cotton  with  Copperas. — This  salt  is  usually  employed  for 
mordanting  inferior  qualities,  while  nitrate  of  iron  is  used  for  better  qualities  of  black. 

(a)  Steep  a  test  skein  of  cotton  in  the  sumac  bath  as  before  described ;  pass  through 
a  bath  containing  10  per  cent  copperas  at  140°  F.,  then  through  a  weak  bath  of  lime  water. 


Fig.  250. — Friction  Mangle  and  Sizing  Machine  for  Heavy  Goods. 

Wash  and  dye  with  15  per  cent  Logwood  extract.     After  dyeing  pass  back  into  c()])peras 
bath  for  a  short  time  to  fix  any  excess  of  coloring  matter;  finally  soap  off. 

(b)  Sometimes  bluestone  is  added  together  with  the  copperas  as  a  mordant  for  the 
purpose  of  improving  the  tone  of  the  black  obtained  and  also  to  increase  its  fastness  to 
light.  Mordant  a  test  skein  of  cotton  with  sumac  as  before  described;  pass  through  a 
bath  containing  10  per  cent  copperas  and  5  i)er  cent  l)luestone  at  140°  F.,  then  through  a 
weak  bath  of  lime  water.  Wash  and  dye  with  15  per  cent  Logwood  extract  and  3  per 
cent  Fustic  extract;  after  dyeing  add  to  the  dyebath  5  per  cent  copperas,  and  boil  for 
fifteen  minutes  longer.     Finally  soap  off. 

,  (c)  In  order  to  give  a  purplish  cast  to  the  black  obtained,  alum  may  be  added  with 
the  iron  as  a  mordant.  Mordant  a  test  skein  of  cotton  with  sumac  as  before;  pass 
through  a  bath  containing  10  per  cent  copperas  and  5  per  cent  alum  at  140°  F.,  then 
through  a  weak  liath  of  lime  water.  Wash  and  dye  with  15  per  cent  Logwood,  and 
finally  soap  off. 

Exp.  181.  Chrome  Black  on  Cotton.— .V'.t'.DU'^h  there  are  a  number  of  methods 


EXPERIMENTAL  STUDIES  489 

whereby  this  black  may  be  obtained  on  cotton,  it  is  not  as  satisfactory  a  black  as  that 
obtained  with  the  iron  mordant. 

(a)  Boil  a  test  skein  of  cotton  in  a  bath  containing  100  per  cent  Logwood  extract 
for  one  hour;  squeeze  and  expose  to  the  air  for  two  hours,  then  work  cold  for  one  hour 
in  a  solution  containing  6  per  cent  chrome  and  5  per  cent  bluestone;  wash,  and  next 
work  in  a  bath  containing  10  per  cent  Logwood  extract;  enter  cold,  and  slowly  raise  to 
the  boil.  Although  a  very  strong  solution  of  Logwood  is  required  for  this  method,  the 
liquors  may  be  kept  for  subsequent  lots  of  cotton,  and  only  slight  additions  of  dyestuff 
need  be  made  to  the  bath  each  time. 

(6)  Chrome  Black  in  One  Bath. — Dissolve  1.5  grams  potassium  bichromate  in  a  small 
quantity  of  water,  and  mix  with  300  cc.  of  a  solution  of  Logwood  extract  at  3°  Tw., 
then  add  3.5  cc.  of  hydrochloric  acid.  Dye  a  test  skein  of  cotton  in  this  solution  for 
one  hour,  entering  cold  and  slowly  raising  to  the  boil.  The  cotton  is  at  first  dyed  a  deep 
blue  color.  Next  work  for  one-half  hour  in  a  bath  containing  5  per  cent  calcium 
acetate,  and  the  color  will  change  to  a  blue  black.  A  modification  of  this  process  is  to 
work  the  cotton  in  a  solution  containing  at  first  only  the  chrome  and  hydrochloric  acid, 
and  adding  the  Logwood  to  the  bath  in  small  portions  at  a  time,  slowly  raising  the  tem- 
perature to  the  boil. 

A  composition  prepared  by  boiling  together  a  solution  of  Logwood  and  chromium 
acetate  has  been  sold  under  the  name  of  Indigo  Substitute.  It  is  a  purplish  blue  liquid, 
and  cotton  is  dyed  by  simply  working  it  in  a  hot  solution  of  the  mixture. 

Chrome  black  on  cotton  is  less  affected  by  acids  than  the  iron  black,  and  it  may  be 
distinguished  by  spotting  with  strong  sulphuric  acid  when  it  becomes  of  a  dark  olive 
color,  whereas  the  iron  black  turns  reddish  brown.  Chrome  black  is  also  quite  fast  to 
scouring  and  fulling,  but  it  is  not  very  fast  to  light,  as  it  assumes  a  greenish  cast.  This 
bad  effect,  however,  may  be  more  or  less  overcome  by  adding  to  the  dyebath  a  small 
amount  of  a  suitable  red  dyestuff,  such  as  Alizarine. 

Exp.  182.  Logwood  with  Copper  Mordant. — Cotton  may  be  dyed  with  Logwood  in 
one  bath  with  this  mordant. 

(a)  Dye  a  test  skein  of  cotton  in  a  bath  of  Logwood  extract  at  3°  Tw.  and  6  per  cent 
copper  acetate,  entering  cold  and  slowly  bringing  to  the  boil,  and  continuing  for  one 
hour.     Wa.sh  in  a  weak  hot  bath  of  lime  water. 

(6)  Another  method  is  the  following:  Prepare  a  bath  of  Logwood  extract  at  3°  Tw., 
and  add  4  per  cent  bluestone  and  4  per  cent  soda  ash.  Dye  a  test  skein  of  cotton  in 
this  bath  at  180°  F.  for  one  hour;  squeeze  and  age  in  the  air  for  several  hours.  In  order 
to  obtain  a  deep  full  black  the  operation  must  be  repeated  two  to  three  times.  The 
method  is  not  a  very  economical  one,  but  it  is  said  to  give  a  color  which  is  very  fast  to 
fulling.  Instead  of  using  the  mi.xture  of  bluestone  and  soda  ash,  copper  carbonate  itself 
may  be  used. 

Exp.  183.  Logwood  Gray  on  Cotton. — This  may  be  produced  in  a  variety  of  ways  by 
using  small  amounts  of  the  coloring  matter. 

(o)  One-bath  Method. — Dye  a  test  skein  of  cotton  in  a  bath  containing  5  per  cent 
Logwood  extract  and  1  per  cent  copperas  at  150°  F.  for  one  hour.  After  dyeing  the  first 
skein,  use  the  same  bath  for  dyeing  three  other  skeins  successively.  Comparatively 
little  precipitate  is  produced  in  the  bath,  and  the  color  is  fully  developed  only  after 
exposure  to  the  air  for  some  time  and  washing. 

(b)  Another  method  is  the  following :  Dye  a  test  skein  of  cotton  in  a  bath  containing 
5  per  cent  Logwood  extract  at  150°  F.  for  one-half  hour;  squeeze,  and  work  in  a  second 
bath  containing  1  per  cent  chrome  at  150°  F.  Finally  wash  and  soap.  Instead  of  using 
chrome  a  bath  of  copperas  may  be  used. 

By  adding  to  the  Logwood  bath  small  amounts  of  Fustic  or  other  coloring  matters,  a 
large  variety  of  different  shades  of  gray  may  be  obtained. 


490 


USE  OF   LOGWOOD   IN   DYEING 


Exp.  184.  Logwood  Purple  on  Cotton. — This  is  obtained  by  mordanting  the  cotton 
with  stannous  chloride,  washing  and  then  dyeing  with  Logwood. 

Steep  a  test  skein  of  cotton  in  a  bath  containing  5  per  cent  stannous  chloride  (brought 
into  solution  by  the  addition  of  the  necessary  hydrochloric  acid) ;  wash,  in  cold  water; 
this  will  cause  the  precipitation  of  the  oxychloride  of  tin  on  the  fiber.  Then  dye  in  a 
bath  containing  10  per  cent  Log\s'ood  extract  in  the  usual  manner.  The  color  so  obtained 
is  rather  fast  to  washing  but  is  not  fast  to  hght. 

Exp.  185.  Logwood  Blue  on  Cotton. — This  is  obtained  by  the  use  of  a  copper  mor- 
dant, but  is  seldom  used  at  the  present  time,  as  it  is  not  at  all  fast. 

Dj-e  a  test  skein  of  cotton  in  a  bath  containing  10  per  cent  Logwood  extract  and  5 
per  cent  copper  acetate;  enter  cold  and  slowly  raise  the  temperature  to  140°  F.  The 
color  produced  in  this  manner  has  a  strong  resemblance  to  vat  Indigo  blue. 


Fig.  251.— Three-Roll  Calender  with  Expander.     (H.  W.  Butterworth  &  Sons  Co.) 


Exp.  186. — Dyeing  Silk  a  Pure  Black  with  Logwood. — By  "  pure  "  black  is  meant 
one  which  does  not  contain  any  weighting  materials.  Mordant  a  test-skein  of  silk 
yarn  in  a  bath  containing  150  cc.  of  water  and  20  per  cent  of  cutch;  enter  at  120°  F., 
and  gradually  bring  to  the  boil,  then  allow  to  cool  in  the  bath  for  one-half  hour;  nexi, 
rinse  the  skein  slightly  and  pass  into  a  bath  of  nitrate  of  iron  at  10°  Tw.,  work  at  120° 
F.  for  fifteen  minutes,  then  pass  through  a  dilute  bath  of  soda  ash,  and  wash  well.  Next 
dye  in  a  bath  containing  150  cc.  of  water  and  25  per  cent  of  Logwood  extract  (solid) 
and  5  per  cent  of  soda  ash;  enter  at  140°  F.,  graduallj^  bring  to  the  boil,  and  dye  at  that 
temperature  for  one-half  hour,  then  wash  well  and  dry. 

Exp.  187.  Valuation  of  Logwood  and  Logwood  Extracts. — The  only  rehable  method  for 
judging  the  tinctorial  power  of  Logwood  chips  or  extracts  i^  to  make  a  comparative  dye- 
test,  using  skeins  of  woolen  yarn  which  have  been  previously  mordanted  with  3  per  cent 
of  chrome  and  1  per  cent  of  sulphuric  acid.  To  conduct  the  test  20  grams  of  the  chips 
are  taken  and  boiled  up  for  fifteen  minutes  with  200  cc.  of  water;  the  extract  is  rim  off 
into  graduated  flask  of  500  cc.  capacity,  and  the  residue  is  again  boiled  for  fifteen  minutes 
with  100  cc.  of  water,  and  the  liquid  poured  into  the  flask.     This  is  continued  until  the 


EXPERIMENTAL  STUDIES  491 

flask  is  filled  to  its  mark.  In  the  case  of  extracts,  10  grams  of  the  pastes  are  taken  or 
5  grams  of  the  solids,  and  dissolved  in  water,  and  diluted  to  200  cc.  The  standards 
for  comparison  are  made  up  in  the  same  way  and  of  the  same  strength.  The  dye-tests 
are  performed  in  the  usual  manner;  that  is  to  say,  matching  the  sample  to  be  tested 
against  the  standard  and  noting  the  relative  amounts  of  the  two  which  are  required. 
In  order  to  determine  the  relative  proportion  of  hematoxylin  and  hematine  (in  other 
words  the  degree  of  oxidation)  it  is  well  to  proceed  as  follows:  Mordant  one  test  skein 
of  wool  with  3  per  cent  of  chrome  and  1  per  cent  of  sulphuric  acid  and  a  second  skein 
with  3  per  cent  of  chrome  and  4  per  cent  of  tartar.  Dye  each  of  these  test  skeins  with 
2  per  cent  of  the  extract  under  examination,  and  compare  them  for  the  depth  of  color 
developed.  The  first  skein  will  show  the  entire  color  present  (both  the  hematoxylin  and 
the  hematine)  whereas  the  second  skein  will  show  principally  the  hematine.  By  com- 
paring the  results  with  tests  on  known  standards  of  oxidation  it  will  be  possible  to 
arrive  at  a  close  approximation  of  the  degree  of  oxidation. 


CHAPTER   XXI 
THE  MINOR  NATURAL  DYES 

1.  Fustic. — This  coloring  matter  is  obtained  from  the  wood  of  a  tree 
botanically  known  as  Morns  iinctoria.  It  is  also  known  as  Cuba  wood  or 
yellow  wood.  It  is  obtained  in  the  West  Indies  and  Central  and  South 
America,  the  best  varieties  being  obtained  from  Cuba  and  Tanipico. 
Fustic  gives  a  bright  j-ellow  color  with  an  alum  mordant,  with  chromium 
an  olive-yellow,  with  iron  a  dark  olive,  with  copper  an  olive,  and  with  tin 
a  bright  orange-yellow.  Fustic  may  be  used  either  in  the  form  of  the 
chipped  wood  or  as  the  extract,  the  latter  being  obtainable  either  as  paste 
or  solid.  At  present  it  is  seldom  used  as  a  self  color,  but  it  still  finds  con- 
siderable use  in  connection  with  Logwood  for  the  dyeing  of  dead-black 
shades. 

Fustic  appears  to  contain  two  coloring  matters,  morintannic  acid  and 
morin.  The  former,  known  also  as  maclurin,  is  readily  soluble  in  water, 
and  may  be  cr3^stallized  from  solution  in  the  form  of  light  yellow  micro- 
scopic needles.  It  has  the  composition  CisHioOc;  when  heated  with  strong 
caustic  alkali  it  is  decomposed  into  phloroglucin  and  protocatechuic  acid. 
It  dissolves  in  cold  concentrated  sulphuric  acid  with  a  yellow  color  and  is 
reprecipitated  on  dilution  with  water.  If  the  strong  acid  solution  is 
allowed  to  stand  for  some  days  it  deposits  brick-red  crystals  of  rufimoric 
acid.  If  a  solution  of  morintannic  acid  is  treated  with  zinc  and  sulphiuic 
acid,  the  solution  becomes  red  and  then  orange,  and  contains  phloroglucin 
and  machromin;  the  latter  crystallizes  in  slender  needles  which  become 
blue  on  exposure  to  the  air.  Hj'drochloric  acid  gives  a  blue  precipitate; 
and  the  alkaline  solution  also  becomes  blue  on  exposure  to  the  air.  A 
solution  of  machromin  with  ferric  chloride  gives  a  violet  color  gradually 
becoming  blue;  mercuric  chloride  gives  the  same  result.  A  solution  of 
morintannic  acid  with  gelatin  gives  a  yellow  precipitate,  with  ferro-ferric 
sulphate  a  greenish  precipitate,  acetate  of  lead  a  yellow  precipitate,  and 
stannous  chloride  an  orange  precipitate.  Morin,  on  the  other  hand,  is 
almost  insoluble  in  cold  water,  and  only  slightly  soluble  iu  boiling  water 

492 


CHARACTERISTICS  OF  FUSTIC  493 

It  is  also  known  as  moric  acid,  and  has  the  formula  CisHiqOg.  It  is  soluble 
in  alkalies,  with  a  j-ellow  color,  from  which  solution  it  is  reprecipitated  by 
the  addition  of  acids.  It  is  soluble  in  alcohol,  and  this  solution  with  ferric 
chloride  gives  an  olive-green  color.  Morin  appears  to  give  much  deeper 
shades  with  chromium  and  almninium  mordants  than  morintannic  acid, 
but  it  gives  lighter  shades  with  iron  mordants.  Morintannic  acid  may  be 
prepared  from  commercial  Fustic  extract  by  allowing  the  concentrated 
sjTupy  solution  to  stand  for  some  days,  when  an  abundant  crystalline 
deposit  will  be  formed;  this  is  washed  rapidly  with  a  little  cold  water  and 
strongly  pressed.  The  resulting  mass  is  boiled  twice  with  water,  whereon 
a  solution  containing  morintannic  acid  will  be  obtained,  the  residue  con- 
sisting of  moric  acid  and  morate  of  liine.     The  aqueous  solution  is  con- 


FiG.  252.— Overhead  Folding  Attachment.     (Curtis  &  Marble.) 

centrated  by  evaporation,  and  precipitated  by  the  addition  of  hydro- 
chloric acid.  Pure  moric  acid  may  be  obtained  from  the  residue  by  treat- 
ing with  cUlute  hydrochloric  acid  (to  decompose  the  calcimn  morate)  and 
dissolving  in  alcohol.  On  diluting  with  water  this  solution  deposits  moric 
acid  in  the  form  of  yellow  needles. 

A  solution  of  Fustic  gives  the  following  reactions: 

Alkalies:  Orange  to  brown  color. 

Weak  acids:   Pale  yellow  precipitate. 

Aluin:  Bright  yellow  precipitate. 

Lead  acetate:  Orange  precipitate. 

Copper  acetate:  Brownish  yellow  precipitate. 

Ferrous  sulphate:  |  ^^  ^^^^  ^j.^^  ^^j^^,^  ^j^^^  brownish  olive  precipitate  on  standing. 

Feme  sulphate:    ) 


494  THE   MINOR   NATURAL   DYES 

Stannous  chloride:   Brownish  yellow  precipitate. 
Copper  sulphate:   Dark  green  precipitate. 
Gelatin:  Yellow  flocculent  precipitate. 

Fustic  occurs  in  commerce  in  the  form  of  log,  chipped,  rasped,  ground, 
or  as  an  extract.  The  extract  is  frequently  sophisticated  with  glucose 
and  Quercitron  bark  extract,  and  varies  in  its  specific  gravity  from  40  to 
51°  Tw,  The  specific  gravity,  however,  like  that  of  Logwood,  is  of  no  guide 
to  its  value,  on  account  of  it  being  increased  by  the  addition  of  adul- 
terants.* The  best  method  of  making  a  valuation  of  Fustic  in  any  of  its 
forms  is  to  conduct  a  series  of  comparative  dye-tests  on  skeins  of  woolen 
yarn  which  have  been  previously  mordanted  with  3  per  cent  of  chrome 
and  4  per  cent  of  tartar,  as  in  the  case  of  Logwood,  or  with  3  per  cent  of 
stannous  chloride  and  5  per  cent  of  oxalic  acid.  The  tests  are  carried  out 
in  the  usual  manner. 

Fustic  is  more  used  on  wool  than  on  cotton,  and  the  general  mordant 
employed  is  chrome,  though  when  bright  yellow  colors  are  desired  alum- 
inium or  tin  mordants  are  used.f  The  color  obtained  with  the  latter, 
however,  is  not  very  fast  to  washing  and  is  quite  fugitive  to  light,  becom- 
ing duller  and  browner  on  exposure.  Even  on  a  chrome  mordant,  how- 
ever, the  color  cannot  be  classified  as  fast  to  light.  In  the  dyeing  of  Fustic 
prolonged  boiUng  must  be  avoided,  as  this  causes  the  color  to  be  dull  and 
brownish,  probably  due  to  the  presence  of  considerable  tannin  matter  in 
the  dyestuff  which  by  protracted  boiling  and  oxidation  suffers  decomposi- 
tion into  brownish  coloring  matters.  The  addition  of  some  glue  solution 
to  the  dyebath  is  said  to  obviate  this  defect. J 

*  By  treating  Fustic  with  a  diazotized  solution  of  aniline  (in  hydrochloric  acid)  a 
paste  product  is  obtained  known  as  Fustin  or  Wool  Yellow.  It  is  an  acid  dye,  but  can 
also  be  used  on  a  chrome  mordant.  It  gives  a  more  intense  but  redder  shade  than 
Fustic,  but  the  colors  obtained  are  not  so  fast.  Osage  Orange  gives  the  same  product 
in  this  respect  as  Fustic.  As  there  are  many  other  yellow  dyes  of  better  quality  than 
this  product,  it  has  little  or  no  use  at  the  present  time. 

t  The  different  metallic  mordants  give  the  following  colors  with  Fustic : 

Chromium brown-yellow 

Aluminium yellow 

Iron olive 

Tin Bright  yellow 

Copper olive 

t  Detection  of  Fustic  on  the  Fiber. — As  the  most  common  mordant  for  Fustic  is 
chromium,  where  this  dye  has  been  used,  the  ash  of  the  fabric  will  generally  contain 
chromium.  In  bright  yellows  or  oranges,  tin  is  liable  to  be  found.  Fustic  is  difficult 
to  distinguish  on  the  fiber  from  Persian  Berries  or  Quercitron  bark,  as  the  reactions  of 
these  are  very  similar.  The  presence  of  Fustic  in  compound  shades  is  also  very  difficult 
to  detect.  In  the  case  of  browns  obtained  with  Logwood,  Alizarine  and  Fustic,  the  dye 
should  be  fast  to  soap,  give  no  color  to  alcohol,  and  if  the  fabric  is  boiled  in  a  solution  of 
aluminium  acetate  a  yellow  solution  with  a  green  fluorescence  should  be  obtained;  this 


OSAGE  ORANGE 


495 


Another  coloring  matter  similar  to  Fustic,  and  which  once  had  consider- 
able use,  is  the  so-called  Young  Fustic.  This  dyestuff  consists  of  the  ground 
wood  of  the  sumac  tree,  Rhus  cotinus.  It  was  employed  in  practically 
the  same  manner  as  Fustic  (which  was  known  as  Old  Fustic),  but  was  a 
much  inferior  dyestuff,  owing  to  its  fugitive  character.  It  has  now  prac- 
tically disappeared  from  trade. 

2.  Osage  Orange  is  a  yellow  dyestuff  apparently  almost  identical  with 
Fustic.  It  is  the  extract  obtained  from  the  wood  of  the  osage  orange  tree 
which  is  found  in  great  abundance  in  the  southwestern  districts  of  the 
United  States.  It  also  is  known  under  the  trade  name  of  Aurantine, 
and  occurs  in  commerce  both  as  the  liquid  extract  of  51°  Tw.  and  the 
solid  or  powdered  extract.  This  dye  was  conmiercially  developed  to  a 
large  extent  during  the  War,  and  now  bids  fair  to  be  a  permanent  feature 
in  the  dyestuff  trade.  Osage  Orange  is  used  in  exactly  the  same  manner 
as  Fustic  and  shows  the  same  reactions  and  qualities  as  to  color.     It  yields 

solution  on  evaporation  with  nitric  acid  becomes  red.     The  following  table  gives  the 
reactions  of  wool  dyed  with  Fustic  on  a  chromium  and  on  a  tin  mordant : 


Reagent. 

Chromium. 

Tin. 

Hydrochloric  acid 

NU. 

Yellow  solution;    colorless 

on  dilution. 

Sulphuric  acid 

Little    change;     solution 
yellow ;      on     dilution 
fiber    lighter,    solution 
colorless. 

Solution  yellow,  remaining 
so  on  dilution. 

Nitric  acid 

Brown;   on  adding  soda, 
red. 

Brown;    on  adding  soda. 

red. 

Stannous  chloride 

Little  action. 

Little  action. 

Caustic  soda 

Fiber    brown;     solution 
colorless. 

Browner;  solution  yellow, 

decolorized    on    adding 
HCl. 

Boiling  alcohol 

Nil. 

Nil. 

Boiling  soap  (1  per  cent) 

Fiber    redder ;      solution 
faint  yfellow. 

Fiber   straw ;    solution 
deeper  yellow. 

Boihng  soda  ash  (^  per  cent). . 

Fiber     redder;     solution 
orange-yellow. 

As  with  soap. 

Boiling  sulphuric  acid  (5  per 
cent) 

Fiber    lighter;     solution 
yellow. 

Fiber  hardly  changed; 
solution  yellow. 

496  THE   MINOR  NATURAL   DYES 

shades  which  are  sHghtly  redder  in  tone  and  somewhat  brighter  than  most 
samples  of  Fustic. 

Fustic  is  still  employed  to  a  very  large  extent  for  the  dyeing  of  heavy 
woolens,  principally  in  compound  shades  with  other  mordant  and  natural 
dyes  such  as  Logwood,  Red-woods,  Archil,  Alizarines,  etc.  It  is  always 
used  with  a  chrome  mordant,  and  it  is  best  that  the  mordant  be  applied 
first  rather  than  after  dj-eing.  It  is  used  in  the  production  of  brown  and 
drab  shades  fast  to  fulUng.  Some  dyers  still  consider  it  the  best  yellow 
coloring  matter  available  for  wool,  though  it  is  not  as  fast  to  hght  as  some 
other  yellow  dyes.  Fustic  is  seldom  used  as  a  self  color  for  the  produc- 
tion of  j'cUows. 

In  silk  dyeing.  Fustic  is  used  to  some  extent  for  the  shading  of  Logwood 
black;  but  beyond  this  it  has  little  or  no  application  to  silk,  at  least  in  this 
country.  It  was  formerly  u^ed  for  the  d3Ting  of  olive  and  brown  shades  in 
connection  with  other  dyewoods. 

3.  Madder. — This  ctyestuff  was  formerly  of  very  gi'eat  importance,  and 
was  largely  cultivated  in  the  southern  part  of  Euro]3e  and  Asia  IMinor.  It 
was  used  for  the  production  of  Turkey  Red  on  cotton  and  the  dj'eing  of 
red  on  wool.  Madder,  however,  has  long  been  replaced  by  the  coal-tar 
Alizarine  which  is  identical  in  composition  and  properties  to  the  natural 
product. 

iMaddcr  is  the  ground  root  of  the  plant  known  as  Rubia  iindorum; 
the  principal  coloring  matters  yielded  by  the  madder  root  are  alizarine, 
purpurin,  pseudo-purpurin,  xanthin,  and  chlorogenin;  the  aqueous  extract 
also  contains  from  10  to  15  per  cent  of  sugar.  The  most  important  of 
these  constituents  is  the  AUzarine,  the  other  coloring  matters,  especially 
the  xanthin  and  chlorogenin,  have  a  deleterious  effect  in  dulling  the  color 
produced  by  the  Alizarine.  The  coloring  matters  exist  in  the  root  in  the 
form  of  glucosides,  which  are  split  up  into  the  dyestuffs  and  a  sugar  through 
the  action  of  a  particular  ferment. 

Alizarine  which  is  the  principal  coloring  matter  of  the  Madder,  may  be 
obtained  therefrom  by  extracting  the  grountl  root  with  alcohol,  c\aporating 
the  solution  to  dryness,  powdering  the  residue,  spreading  it  on  a  filter  paper 
on  a  heated  plate;  the  extract  melts  and  the  paper  absorbs  the  brown 
resinous  matters,  while  the  alizarine  sublimes  on  the  surface  of  the  mass  as 
large  orange-red  crystals. 

Alizarine  possesses  the  characteristics  of  a  phenol,  and  is  readily  soluble 
in  alkalies,  with  red  color;  it  is  only  slightly  solul)le  in  boiling  water  with  a 
yellow  color.     Its  solution  gives  the  following  reactions: 

Alkalies:  Bluish  claret  color. 
Adds:  Brownish  yellow  color. 
Alum:  Brownish  red  precipitate. 
Stannous  chloride:  Brownish  red  precipitate 


PROPERTIES  OF  MADDER  497 

Iron  salts:  Dark  brown  precipitate. 
Copper  salts:   Reddish  brown  precipitate. 
Banum  and  calcium  chlorides:  Violet  precipitates. 
Lead  acetate:  Reddish  violet  precipitate. 

When  Alizarine  is  distilled  with  zinc  it  gives  anthracene,  from  which 
reaction  its  synthetic  preparation  from  the  latter  body  was  finally  dis- 
covered. 

Purpurin,  which  also  exists  in  the  madder  root,  resembles  Alizarine 
but  is  more  yellow  in  color.  It  may  be  prepared  from  Alizarine  by  heating 
the  latter  with  manganese  dioxide  and  sulphuric  acid. 

Madder  was  used  principally  m  the  form  of  the  gi'ound  root,  but  there 
were  also  numerous  extracts  and  preparations  made  for  the  use  of  the  dyer. 
Garancin  was  obtained  by  treating  the  wet  paste  of  Madder  with  concen- 
trated sulphuric  acid;  100  parts  of  Madder  gave  from  30  to  40  parts  of 
Garancin,  but  this  possessed  four  to  five  times  the  dyeing  power  of  the  orig- 
inal Madder.  It  is  supposed  that  other  bodies  which  detracted  from  the  good 
color  of  the  Alizarine  in  the  Madder  were  removed  by  this  treatment,  and 
also  any  coloring  matter  which  may  have  been  combined  as  metallic  salts 
was  liberated  and  rendered  more  active  in  dyeing.  Garanceux  was  obtained 
from  spent  JVIadder  by  the  same  process  as  the  above;  its  coloring  power, 
however,  was  only  about  one-third  that  of  good  Garancin.  Fleurs  de  gar- 
ance,  or  flowers  of  madder,  was  prepared  by  treating  Madder  with  dilute 
sulphuric  acid,  whereby  any  yellow  coloring  matters  were  removed.  To 
prepare  it,  mix  100  parts  of  Madder  with  1  part  sulphuric  acid  and  1000 
parts  water,  and  allow  the  mixture  to  macerate  for  ten  hours ;  filter,  wash 
the  paste,  press  and  dry.  The  acid  liquors  from  this  process  were  used 
for  the  manufacture  of  alcohol,  as  they  contained  considerable  sugar;  100 
parts  Madder  yielded  about  10  parts  alcohol. 

Madder  gives  the  following  colors  with  the  different  mordants: 

Chromium:  Bluish  red  to  crimson. 
Aluminium:   Pink  to  scarlet. 
Iron:   Maroon  to  reddish  brown. 
Coppei-:  Yellowish  brown. 
Tin:  Reddish  orange. 

Madder  is  still  used  in  the  woad  indigo  vat,  but  in  this  case  it  is  more 
employed  for  its  fermenting  properties  than  for  any  coloring  power. 

The  chief  varieties  of  Madder  are  Dutch,  Alsatian,  Avignon,  and  Turk- 
ish. Dutch  Madder  is  coarsely  ground,  and  if  kept  in  a  moist  place  tends 
to  cake  together.  Crop  Madder,  which  is  the  ground  inner  portion  of  the 
root,  is  considered  as  the  best  quality,  while  the  outer  part  is  known  as 
mulle  madder,  and  is  the  poorest.  Alsatian  Madder  is  very  like  the  Dutch. 
Avignon  Madder  is  known  in  two  varieties,  the  palus  and  the  rosee.  The 
former  is  much  the  darker  in  appearance,  due  to  the  nature  of  the  soil  on 


498  THE   MINOR   NATURAL   DYES 

which  it  is  gi'own.  Avignon  Madder  does  not  require  to  be  matured  by 
storage  for  as  long  a  time  as  Dutch  and  Alsatian  Madders,  which  should 
be  stored  in  casks  for  two  years  before  use.  Turkish  Madder  is  exported 
chiefly  from  Smyrna  and  is  very  rich  in  coloring  matter. 

The  color  solution  of  Madder  is  best  prepared  by  boiling  the  rasped 
wood  in  water  and  straining  through  cheesecloth,  making  use  of  the  clear 
solution  for  the  dyebath.  The  colors  obtained  on  the  various  mordants 
are  not  as  clear  and  bright  as  those  produced  from  Alizarine.  The  use  of 
calcium  acetate  in  the  dyebath  serves  the  purpose  of  brightening  the  color; 
in  case  the  water  contains  considerable  lime  this  addition  need  not  be 
made,  but  sufficient  acetic  acid  should  be  added.  Madder  may  be  dyed 
in  a  single  bath,  using  5  per  cent  of  alum,  4  per  cent  of  tartar,  4  per  cent  of 
calcium  acetate,  and  10  per  cent  of  Madder;  enter  the  material  cold  and 


Fig.  2.53.— Lustering  Machine  fur  \N'ool,  Uniuns,  Silk  and  Half-Silk  Goods. 

slowly  bring  to  the  boil,  and  maintain  at  that  temperature  for  one  hour. 
This  method  is  used  only  for  the  dyeing  of  light  colors,  as  otherwise  there 
would  be  considerable  precipitation  of  coloring  matter  in  the  dyebath.  A 
pale  brownish  drab  stain  on  wool  may  be  produced  by  boiling  with  a  decoc- 
tion of  Madder  without  the  use  of  any  mordant  whatever.  This  method, 
in  fact,  has  been  used  in  practice.  The  colors  produced  with  Madder  on 
either  a  chromium  or  an  aluminium  mordant  may  be  considerably  bright- 
ened by  the  addition  of  a  small  amount  of  tin  crystals  to  the  mordanting 
bath.  In  order  fully  to  develop  the  coloring  power  of  Madder  it  is  neces- 
sary that  the  temperature  of  the  dyebath  be  gradually  and  regularly 
elevated  to  the  boiling  point.  The  addition  of  a  small  amount  of  sumac 
(or  other  tannin  extract)  to  the  dyebath  serves  to  give  better  exhaustion 
of  the  coloring  matter. 

4.  Archil. — This  coloring  matter  is  obtained  from  certain  species  of 
lichens,  the  principal  varieties  of  which  are  Roccella  tindoria,   Roccella 


ARCHIL 


499 


fudformm,  and  Variolaria  ordna.*    The  dyestuff  occurs  in  the  form  of  a 
paste,  and  is  prepared  by  treating  the  Hchens  to  a  process  of  oxidation  in 
the   presence   of  ammonia.     The   principal   color-producing   compounds 
existmg  m  the  lichens  are  crythrin,  lecanoric  add,  and  evernic  add      The 
lichens  are  torn  up  into  small  fragments,  placed  in  iron  drums  provided 
with  stirrers,  and  mixed  with  a  dilute  solution  of  anmionia.     The  tempera- 
ture IS  kept  at  about  100°  F.  for  several  days,  during  which  time  the  mass 
undergoes  a  fermentation  which  causes  the  development  of  the  coloring 
matter.    When  the  latter  ceases  to  increase  (which  is  determined  by  making 
tests  from  time  to  time)  the  fermentation  is  stopped.     The  product  so 
obtained  IS  Archil  paste;  Archil  liquor  is  prepared  by  removing  the  fibrous 
matter  of  the  plant.     French  purple  is  a  preparation  of  Archil  which  is  said 
to  give  faster  shades  than  the  ordinary  product;  it  is  made  by  treating  the 
hchens  with  a  dilute  solution  of  ammonia,  acidulating  the  resulting  liquid 
with  hydrochloric  acid,  which  precipitates  the  coloring  matters      This 
precipitate  is  washed,  dissolved  in  strong  ammonia,  and  kept  for  about 
three  weeks  at  a  temperature  of  160°  F.,  during  which  time  a  fine  purple 
color  is  developed;    calcium  chloride  i^  added  and  a  purple  lake  is  pre- 
cipitated.    When  used  for  dyeing  this  lake  is  mixed  with  an  equal  weight 
of  oxalic  acid  and  dissolved  in  water. 

A  solution  of  Archil  gives  the  following  reactions: 
Acids:  Solution  yellower. 
Alkalies:  Solution  bluer. 
Lead  acetate:  Crimson  precipitate. 
Calcium  chloride:  Red  precipitate. 
Stannous  chloride:  First  redder,  then  yellower. 
Alum:  Solution  redder. 
Basic  alum:  Crimson-red  precipitate. 

The  coloring  principle  of  prepared  Archil  is  known  as  orcein. 

Archil,  or  Orchil,  was  formerly  prepared  by  treating  the  lichens  with 
water  contaming  putrid  urine,  and  at  a  subsequent  stage  with  slaked  lime 
Archil  IS  chiefly  employed  for  the  dyeing  of  carpet  yarns.  Archil  is  a  sub- 
stantive dye  and  may  be  used  on  wool  or  silk  in  a  neutral,  acid,  or  slightly 
alkalme  bath.  It  dyes  very  slowly  and  evenly  and  in  heavy  shades  it  has 
great  depth  and  body  which  cannot  be  matched  advantageously  with  any 
of  the  coal-tar  dyes.  Both  Archil  and  Cudbear  dye  best  in  a  neutral  bath 
and  when  used  alone  they  give  bluish  red  or  magenta  shades.  In  acid 
baths  the  shade  is  redder  and  brighter.  Silk  is  usually  dyed  in  a  soap 
bath  broken  with  acetic  acid. 

,  1  These  lichens  are  found  in  large  quantity  in  Mediterranean  districts;  also  in  Scot- 
land and  Norway.  They  are  also  found  in  certain  portions  of  Lower  California,  and 
attempts  have  been  made  during  the  past  few  years  to  develop  an  Archil  industry  in 
that  country  The  quality  and  exact  color  produced  by  Archil  varies  considerably  with 
the  source  of  the  lichen  from  which  the  dye  is  obtained 


500  THE   MINOR  NATURAL  DYES 

Archil*  occurs  in  trade  in  three  forms:  (1)  as  a  thick  Hqiior  called  Archil; 
(2)  as  a  paste  called  Persis ;  and  (3)  as  a  reddish  brown  or  purple  powder 
termed  Cudbear.  The  liquor  varies  in  specific  gravity  from  8  to  20°  Tw. ; 
the  paste  is  usually  a  35  per  cent  one,  but  is  sometmies  as  low  as  20  per 
cent.  Archil  is  sometimes  adulterated  with  other  vegetable  coloring  mat- 
ters such  as  Logwood,  Sapan,  Brazil-wood,  etc.,  and  also  with  coal-tar  dyeS; 
especially  Magenta.  Pure  Cudbear  is  obtained  from  a  lichen  known  as 
Lecanora  tartarea.  It  is  prepared  and  used  in  exactly  the  same  manner  as 
Archil,  and  gives  the  same  colors;  it  also  yields  the  same  reactions.  In 
fact,  the  two  dyes  commercially  are  not  distinguished. 

5.  Quercitron.— This  dyestuff  is  from  the  inner  bark  of  a  species  of 
oak,  the  botanical  name  of  which  is  Quercus  citrina  or  Quercus  tinctoria. 
It  is  found  principally  in  Pennsylvania,  Georgia,  and  the  Carolinas.  Its 
dyeing  properties  are  due  to  two  principles,  quercitrin,  C3GH3SO20,  and 
quercetin,  C92H240n.  The  best  varieties  are  shipped  from  Philadelphia, 
New  York,  and  Baltimore;  the  Philadelphia  variety  being  the  most 
highly  prized,  t  It  is  principally  used  in  calico  printing  for  the  production 
of  compound  shades  in  conjunction  with  mordants  of  aluminium,  tin 
chromium,  and  iron.  It  is  also  employed  in  woolen  printing  and  leather 
dj'^eing.  In  the  dry  condition.  Quercitron  is  of  a  yellow  or  buff  color,  being 
a  mixture  of  the  fibers  with  a  fine  powder  of  a  bitter  and  astringent  taste. 
The  extract  when  freshly  prepared  is  nearly  transparent  and  of  a  dull 
orange-red  color,  which  on  standing  deposits  a  yellow  crystalline  powder, 
and  becomes  turbid  and  considerably  thicker.  The  extract  is  adulterated 
chiefly  with  molasses.  In  the  forni  of  extract  it  is  know^n  as  Bark  Extract 
and  is  usually  sold  at  a  density  of  51°  Tw. 

Patent  Bark  is  prepared  by  boiling  ground  Quercitron  bark  with  dilute 
sulphuric  acid,  the  product  being  washed  and  dried.  Its  chief  use  is  as  a 
substitute  for  Flavine  in  wool  dyeing, 

Flavine  is  a  very  pure  dry  extract  of  the  coloring  matter  of  Quercitron 
bark.  J  The  best  varieties  contain  a  large  proportion  of  quercetin,  and 
yield  yellow  colors  of  great  brightness.  §     Flavine  is  still  somewhat  used  in 

*  Archil  is  also  still  used  to  a  considerable  exteiit  for  "  bottoming  "  Indigo  on  \tool. 
It  is  also  used  in  the  dyeing  of  browns,  maroons,  (clarets  and  similar  compound  shades 
on  wool. 

t  (Ju(>rcitron  is  essentially  an  American  (lye-])r()duct,  it  has  long  been  made  in  largo 
quantities  in  this  country,  and  strange  to  say,  has  been  extensively  exported  to  CJer- 
.many.  Quercitron  is  not  much  used  in  this  coimtry  for  the  dyeing  of  textiles,  but 
it  still  has  consideraV)le  vogue  in  calico  printing  and  leather  dyeing. 

J  The  coloring  power  of  Flavine  is  from  twelve  to  twenty  times  that  of  Quercitron 
bark. 

§  When  dry  Quercitron  extract  is  treated  with  concentrated  sulphuric  acid  a  sul- 
phonic  acid  derivative  is  a{)parently  formed.  This  acts  as  a  yellow  acid  dye  for  unmor- 
danted  wool. 


CUTCH  501 

conjunction  with  Cochineal  for  the  production  of  bright  yellowish  scarlet 
colors.* 

The  colors  o])tained  from  Quercitron  and  Flavine  are  dulled  by  pro- 
longed boihng  in  the  dyebath  owing  to  the  presence  of  considerable  tannin. 
The  addition  of  glue  solution  is  beneficial  hi  tliis  respect. 

6.  Cutch. — C'utch,  or  Catechu,  is  the  dried  extract  obtained  from  sev- 
eral Indian  trees,  a  species  of  Acacia,  the  chief  variety  being  Acacia  catechu. 
The  principal  varieties  are  Bombaj^  Bengal,  and  Gambler  Cutch,  Bom- 
ba}^  Cutch  is  ol^tained  from  the  fruit  and  wood  of  the  Arcea  catechu,  a 
kind  of  pahn.  Bengal  Cutch  is  ol^tained  from  the  twigs  and  unripe  pods 
of  the  Mhyiosa  catechu.  The  above  two  varieties  are  very  sunilar  in 
appearance,  coming  into  commerce  in  the  form  of  large  blocks  of  a  dark 
brown  color,  weighing  from  30  to  40  lbs.  and  packed  in  leaves.  They  are 
hard  but  brittle,  and  are  imported  from  Java,  Singapore,  Peru,  and  the 
East  Indies,  Gambler  Cutch,  called  also  cubical  or  yellow  cutch,  is  obtained 
from  the  leaves  of  the  Uncaria  gambier,  and  occurs  in  trade  in  the  form  of 
small  cubes.  It  is  much  more  yellow  in  appearance  than  the  two  other 
varieties  and  is  also  much  less  soluble  in  cold  water.  It  has  a  dull,  earthy 
fracture  and  is  porous.  The  best  variety  is  gi'own  in  Rhio,  in  the  Isle  of 
Brittany,  and  is  imported  from  Singapore,  Another  variety  of  Cutch  is 
kino,  or  gum  kino,  which  is  obtained  from  the  Pterocarpus  marswpium.  It 
has  a  reddish  brown  color  and  a  highly  lustrous  fracture, 

Cutch  contains  two  principal  coloring  matters,  catechin,  C19H20O2,  and 
catechii-tannic  acid,  C38H3GO16H2O,  It  is  chiefly  used  in  cotton  dyeing  and 
in  calico  printing  for  the  production  of  brown  shades  or  as  a  tannin  mor- 
dant to  be  topped  with  basic  or  other  colors.  Good  qualities  of  Cutch 
should  not  contain  more  than  5  per  cent  of  ash  on  ignition,  nor  more  than 
12  per  cent  of  matter  insoluble  in  alcohol.  It  is  frequently  adulterated 
with  starch,  dried  blood,  sand,  and  clay.  Starch  is  detected  by  treating 
the  sample  with  alcohol,  filtering,  and  dissolving  the  residue  in  hot  water, 
cooling,  and  testing  for  starch  with  an  iodine  solution.  Pure  Cutch  gives 
a  decided  green  color  with  solutions  of  ferric  salts,  so  the  addition  of  other 
tannin  matters  may  be  recognized  by  the  modified  color  given  with  ferric 
salts.  Sand,  clay,  etc.,  are  easily  detected  by  making  up  a  decoction  of  the 
sample  and  observing  the  amount  of  insoluble  residue  which  remains,  as 
pure  samples  should  be  almost  entirely  soluble  in  hot  water.  Blood  may  be 
detected  in  a  similar  way  as  starch,  by  treating  the  sample  with  alcohol,  the 

*  Neither  Quercitron  nor  Fustic  are  equal  to  certain  of  the  mordant  dyeing  coal-tar 
dyes  in  respect  to  purity  and  brightness  of  shade  or  fastness  to  light.  Tartrazine  is  an 
acid  yellow  of  great  brightness  and  intensity  which  is  much  superior  to  these  natural 
yellow  dyes  in  fastness  to  light.  Milling  Yellow  O  is  a  mordant  dye  which  is  faster  both 
to  light  and  fulling.  Chrysophenine  is  a  substantive  dye  which  gives  bright  yellow  shades 
on  wool  of  great  fastness  to  light. 


502 


THE    MINOR   NATURAL    DYES 


residue  being  dried  and  heated  in  a  test  tube,  wlion.  if  blood  is  present, 
ammonia  and  offensi^•e  odors  are  given  off. 

As  already  mentioned,  Cutch  contains  two  coloring  principles ;  the  one 
is  solul)le  in  cold  water  and  is  termed  catechu-tannic  acid,  or  mimotannic 
acid;  the  other  is  nearty  insoluble  in  cold  water  and  is  termed  catechin  or 
catechuic  acid,  a  brown  amorphous  substance.  Catechu-tannic  acid  may 
be  obtained  by  boiling  pulverized  Cutch  with  water,  allowing  the  solution 


Fig.  254.— SLx-Roll  CakiKki   Hydraulic.     (11.  W.  Buttenvorth  &  Sons  Co.) 


to  stand  for  several  days,  when  the  catechin  separates  out  and  may  be 
filtered  off.  The  filtrate  is  evaporated  to  dryness  and  treated  with  alcohol 
to  remove  impurities.  The  product  is  a  reddish  brown  powder  soluble  in 
water  and  alcohol,  but  not  soluble  m  dry  ether.  With  ferric  salts  it  gives  a 
gra}-ish  green  precipitate,  and  gives  no  reaction  with  ferrous  salts.  Its 
aqueous  solution  is  precipitated  by  gelatin,  albumin,  and  sulphuiic  acid. 
Cutch  may  contain  from  35  to  55  per  cent  of  catechu-tannic  acid,  according 
to  its  source.     With  alkalies  catechu-tannic  acid  forms  soluble  salts,  the 


CUTCH     .  503 

solutions  of  which  rapidly  oxidize  on  exposure  to  the  air  and  become  of  a 
reddish  color. 

Catechin  forms  that  part  of  Cutch  insoluble  in  cold  water.  It  is  obtained 
in  the  pure  state  by  taking  the  solid  which  separates  out  after  boiling  Cutch 
with  water  and  cooling;  it  is  purified  by  redissolving  in  hot  water,  boiling 
with  anmial  charcoal  to  decolorize  it,  filtering  hot,  and  allowing  to  cool. 
These  operations  may  have  to  be  repeated  several  times.  The  product 
obtained  is  in  the  form  of  white  silky  crj^stalline  needles,  which  are  very 
slightly  soluble  in  water,  Catechin  precipitates  albumin,  but  not  gelatin. 
When  dissolved  in  concentrated  sulphuric  acid  it  gives  a  purplish  colored 
solution.  Though  sometianes  called  catechuic  acid,  catechin  has  no  acid 
properties,  and  is  neutral  to  litmus.  When  dissolved  in  solutions  of  alka- 
line carbonates  it  rapidly  absorbs  oxygen  from  the  air  and  becomes  dark 
red  in  color ;  and  on  the  addition  of  an  acid  dark  red  ruhinic  acid  is  precip- 
itated. If  caustic  alkalies  are  used  as  the  solvent,  then  a  very  dark  brown, 
nearly  black,  precipitate  oi  japonic  acid  is  obtained  under  similar  conditions. 
This  same  substance  i3  formed  when  a  decoction  of  Cutch  is  oxidized  with 
potassium  bichromate;  and,  in  fact,  it  is  on  this  property  that  the  dyeing 
powers  of  Cutch  depend. 

Dyers  utilize  the  coloring  properties  of  both  catchin  and  the  catechu- 
tannic  acid,  but  the  calico  printer  requires  chiefly  the  catechin.  In  gen- 
eral, Cutch  is  used  in  cotton  dyeing  for  the  production  of  browns  and  as  a 
tannin  mordant;  it  is,  however,  somewhat  used  in  woolen  and  silk  dyeing, 
being  employed  in  the  latter  chiefly  as  a  weighting  and  mordanting  agent 
in  the  production  of  blacks.  It  is  also  used  for  the  dyeing  and  preserving 
of  sails  and  fishing  nets,  as  well  as  in  medicine  as  an  astringent,  and  also  in 
the  tanning  of  leather, 

Cutch  is  best  applied  to  cotton  by  boiling  the  goods  in  a  decoction  of  the 
dyestuff  and  then  allowing  to  stand  for  some  time  after  which  the  cotton 
is  taken  out,  squeezed,  and  worked  in  a  hot  bath  containing  potassium 
bichromate,  which  acts  on  the  soluble  catechin,  and  catcchu-tannic  acid  to 
produce  insoluble  japonic  acid  on  the  fiber.*  Some  dyers  enter  the  cotton 
into  a  hot  bath  of  Cutch,  then  work  it  for  some  hours  without  further 
application  of  heat,  and  treat  it  as  before  with  chrome.  It  is  possible  to 
use  bluestone  instead  o:  chrome,  and  if  the  color  is  developed  by  the 
former  it  appears  much  yellower  and  not  quite  so  full  in  shade  as  the  colors 
produced  by  the  latter.  If  bluestone  is  used,  it  is  the  better  plan  to  add  it 
directly  to  the  bath  containing  the  Cutch,  and  afterwards  to  develop  in 

*  Detection  of  Cutch  on  Dyed  Fabrics. — Generally  speaking,  the  color  of  Cutch  is 
but  little  changed  by  reagents.  Sulphuric  and  hydrochloric  acids  have  but  little  action. 
With  nitric  acid  the  color  is  changed  to  orange.  Ammonia  has  no  action.  Boiling 
solutions  of  bleaching  powder  destroy  the  color  more  or  less.  The  ash  will  be  found 
to  cor.tnin  chromium,  and  very  often  a  little  copper. 


504  THE   MINOR   NATURAL   IJYlvS 

the  usual  way  with  chrome.  In  the  latter  case,  the  shades  are  fuller  and 
faster  to  light  than  would  be  the  case  if  no  bluestone  were  used.  Copperas 
may  also  be  added  to  the  bath  for  the  purpose  of  darkening  the  shade. 
It  is  advisable  when  dyeing  very  dark  Cutch  browns  to  first  work  in  a  fairly 
weak  bath,  develop  in  the  chrome  and  afterwards  work  in  the  Cutch  bath 
again,  and  again  develop  with  chrome,  and  repeat  this  until  the  required 
depth  of  shade  is  obtained.  By  this  means,  darker,  fuller,  and  more  level 
shades  may  be  obtained  than  b^^  using  very  strong  solutions  of  Cutch. 
This  method  is  especially  applicable  to  the  dyeing  of  warps  and  cotton 
pieces.  It  should  be  noted  that  the  presence  of  copper  in  the  color-lake 
appears  to  make  it  faster  to  light.  Instead  of  using  the  copper  sulphate 
directly  in  the  Cutch  bath,  as  is  usually  done,  the  cotton  may  be  worked 
in  a  cold  solution  of  the  salt,  either  on  coming  out  of  the  Cutch  bath  or 
after  being  developed.  Though  chrome  and  bluestone  are  the  chief  metallic 
salts  employed  for  fixing  Cutch  in  cotton  dyeing,  other  salts  may  also  be 
used.  Aluminium  salts  give  a  yellowish  brown  color,  while  tin  salts  give  a 
still  yellower  color;  copperas  gives  a  brownish  gray.  Cotton  ctyed  with 
Cutch  has  the  property  of  being  afterwards  dyed  with  the  basic  and  with 
alizarine  (or  natural)  dyestuffs.  In  the  former  case  it  is  the  catechu- 
tannic  acid,  or  the  products  formed  from  it  by  oxidation,  that  act  as  the 
mordant;  in  the  latter  case  it  is  the  chromium  or  copper  fixed  in  the  fiber 
which  acts  as  the  mordant.  It  is  apparent,  therefore,  that  if  the  tone  of  a 
Cutch  Ijrown  has  to  be  altered  this  may  be  accomplished  by  any  suitable 
dyestuff  of  the  above  groups.  In  the  case  of  the  coloring  matters  requiring 
a  metallic  mordant,  the  dyestuff  may  be  added  directly  to  the  Cutch  bath, 
when,  of  course,  the  color  produced  bj'-  it  would  be  developed  at  the  same 
time  as  the  Cutch.  With  the  basic  colors,  however,  it  would  be  necessary 
to  first  dye  the  Cutch  brown  and  then  top  off  in  a  separate  bath  with  the 
basic  color. 

At  the  present  time  Cutch  is  very  little  used  as  a  dyestuff  for  wool, 
although  for  the  production  of  certain  brown  shades  it  might  be  emploj^ed 
with  advantage.  The  objections  to  the  use  of  Cutch  are  several:  (a) 
The  wool  acquires  a  harsh  feel;  this  might  be  remedied  to  a  certain  extent 
by  using  only  the  catechin,  but  this  is  too  expensive,  (h)  The  best  and 
fastest  shades  are  produced  by  the  so-called  "  saddening  "  process;  that  is, 
first  boiling  the  wool  with  the  coloring  matter  and  then  fixing  in  a  fresh 
l)ath  with  a  solution  of  a  metallic  salt.  As  this  process  is  not  a  very 
convenient  one  for  dyeing  to  shade,  it  is  easy  to  understand  why  Cutch  is 
not  much  used.  The  manner  of  dyeing  wool  with  Cutch  is  very  similar 
to  that  for  the  dyeing  of  cotton,  except  that  boiling  solutions  are  used. 
Cutch  may  also  be  used  on  wool  in  conjunction  with  such  dyes  as  Baxwood 
and  Camwood.  By  first  mordanting  with  chrome  or  other  metallic  salt 
(bluestone  or  copperas),  lighter  shades  are  obtained  than  when  the  sadden- 


COCHINEAL  505 

ing  method  is  used.  The  colors  obtained  with  chrome  are  fairly  fast  to 
light  and  milling,  and  by  the  addition  of  a  little  bluestone  to  the  Cutch 
bath  these  properties  are  increased. 

In  silk  dyeing  cutch  is  used  for  two  purposes.  One  is  for  the  dyeing  of 
silk  plush  an  imitation  of  sealskin ;  in  which  case  the  silk  is  dyed  in  a  sunilar 
manner  to  cotton.  The  second  is  the  use  of  Cutch  in  black  dyeing,  when 
the  method  is  to  first  mordant  the  silk  with  nitrate  of  iron,  and  dye  with 
Prussian  Blue,  after  which  the  silk  is  worked  in  a  strong  decoction  of  Cutch, 
or  better,  gambler,  to  which  may  be  added  a  small  amount  of  tin  crystals. 
The  silk  absorbs  a  large  percentage  of  catechin,  and  is  then  mordanted 
with  pyrolignite  or  nitrate  of  iron  and  dyed  in  the  usual  ziianner.  This 
method  is  used  in  the  production  of  the  so-called  "  Lyons  "  black,  where  it 
is  desired  to  weight  the  silk  about  10  per  cent. 

7.  Cochineal. — This  coloring  matter  is  derived  from  an  animal  source. 
It  consists  of  the  bodies  of  the  female  insects  known  as  Coccus  cacti; 
thej'^  are  found  in  Mexico  and  Central  America  and  other  tropical  and  sub- 
tropical countries,  and  grow  on  certain  kinds  of  cactus.  At  the  proper  time 
the  insects  are  collected  and  killed  by  being  steamed  or  dried  in  hot  stoves; 
the  former  gives  the  black  cochineal  and  the  latter  the  silver  cochineal. 

The  coloring  principle  of  Cochineal  is  carminic  acid.  The  aqueous  solu- 
tion of  Cochineal  yields  the  following  reactions: 

Acids:    Yellowish  color. 

Alkalies:  Violet  color.  > 

Lime  water:   Violet  precipitate. 

Alum:  Slowly  forms  red  precipitate. 

Aluminium  chloride:   Reddish  violet  precipitate. 

StanpMus  chloride:   Violet  precipitate. 

Stannic  chloride:   Bright  scarlet  color. 

Ferrous  sidphate:  Violet  gray  precipitate. 

Copper  sulphate:   Violet  precipitate. 

Lead  acetate:  Violet  precipitate. 

Zinc  sulphate:  Violet  precipitate. 

Oxalic  acid:  Red  precipitate. 

Cochineal  was  formerly  very  extensively  employed  for  the  production 
of  bright  scarlets  and  reds  on  wool ;  it  is  still  used  to  some  extent  for  this 
purpose,  but  has  been  largely  replaced  by  the  acid  scarlets.  The  scarlet 
cloth  for  the  English  army,  however,  is  still  dyed  with  Cochineal.  In  cotton 
dyeing  Cochineal  has  no  application,  though  small  quantities  are  used  in 
printing.  Cochineal  gives  the  following  colors  with  the  different  mor- 
dants : 

Chromium:    Purple. 
Aluminium:  Crimson. 
Iron:  Purple. 
Copper:  Claret. 
Tin:  Scarlet. 


506 


THE   iMINOR   NATURAL   DYES 


The  principal  colors  are  the  crimson  with  alum  and  the  scarlet  with  tin. 
Cochineal  scarlet  is  faster  to  light  than  the  acid  scarlets;  it  is  also  quite 
fast  to  washing  and  fulling,  but  becomes  a  little  bluer,  though  it  does  not 
bleed.  The  solution  of  the  coloring  matter  for  dyeing  is  best  prepared  by- 
boiling  the  powdered  cochineal  insects  in  water  and  straining  the  solution. 

Ammoniacal  Cochineal  is  a  preparation  obtained  by  steeping  ground 
Cochineal  in  ammonia  water  for  several  days,  three  parts  of  ammonia  being 
used  for  one  part  of  Cochineal.  A  chemical  reaction  takes  place  resulting  in 
the  formation  of  a  carminamide  from  the  carminic  acid.  The  mixture  is 
then  heated  to  drive  off  the  excess  of  ammonia,  and  hydrated  aluminium 


Fig.  255. — Tentering  and  Drying  Machine  for  Finishing  Cloth.     (D.  R.  Kenyon  &  Son.) 


oxide  is  added,  and  the  heating  continued  until  all  of  the  ammonia  is 
removed ;  then  the  mass  is  pressed  into  cakes.  It  is  used  for  dyeing  purple 
and  crimson,  and  for  rose  reds  in  connection  with  ordinary  Cochineal.  Its 
color  is  not  as  readily  affected  by  acids  as  that  of  the  other  Cochineal. 
It  also  gives  a  fine  purple  precipitate  with  oxj^chloride  of  tin. 

A  good  quaUty  of  Cochineal  should  not  give  more  than  1  per  cent  of  ash 
on  ignition.  It  is  frequently  adulterated  with  half-exhausted  Cochineal 
which  is  made  to  resemble  white  or  silver  Cochineal  by  drying  and  agitating 
with  barium  sulphate,  white  lead,  etc.  Black  Cochineal  is  also  adulterated 
with  black  iron,  sand,  graphite,  and  black  oxide  of  manganese.  These 
mineral  adulterants  are  easily  detected  by  powdering  the  sample  and 


COCHINEAL  CARMINE  507 

treating  with  water,  when  the  mineral  matters  will  in  most  cases  fall  to 
the  bottom.  Occasionally,  adulteration  is  practiced  by  adding  extract  of 
Brazil-wood.  This  may  be  detected  by  treating  the  sample  with  water, 
adding  an  excess  of  lime  water,  which  completely  precipitates  the  coloring 
matters  of  the  Cochineal,  while  if  Brazil-wood  is  present  the  filtered  liquid 
will  have  a  purple  or  violet  color.  The  value  of  different  samples  of  Cochi- 
neal is  best  estimated  by  dissolving  a  given  weight  of  the  powdered  sam- 
ples in  water  and  observing  the  amount  of  standard  alum  solution  neces- 
sary to  precipitate  the  coloring  matters  completely.  A  more  accurate 
method,  perhaps,  is  to  conduct  a  series  of  comparative  dye- tests,  using  test 
skeins  of  woolen  yarn  previously  mordanted  with  tin  or  alumina. 

Cochineal  carmine  or  carmine  lake  is  a  brilliant  red  pigment  produced 
b}^  precipitating  a  decoction  of  Cochineal  with  alumina.  Its  manufacture, 
however,  is  still  maintained  as  a  trade  secret.  It  contains  a  large  amount 
of  alumina  and  lune,  combined  Avith  a  certain  amount  of  nitrogenous  matter, 
which  seems  to  be  essential  to  its  formation.  It  is  chiefly  used  by  paper 
stainers  and  calico  printers.  Cochineal  carmine  is  liable  to  be  adul- 
terated with  starch,  china  clay,  vermihon,  and  various  pigment  colors. 
These  additions  may  be  detected  by  treating  the  sample  with  dilute 
ammonia  water,  which  will  readilj^  and  completely  dissolve  pure  samples, 
while  if  any  of  the  above-named  substances  are  present  they  will  be  left  as 
insoluble  matters.  The  ash  should  be  under  10  per  cent  and  the  water 
should  not  be  over  20  per  cent.  The  ash  should  be  examined  for  tin, 
which,  if  present,  in  any  considerable  amount  indicates  the  presence  of 
Biebrich  Scarlet  lake,  which  closely  resembles  Cochineal  carmine  in  many 
of  its  properties,  and  is  somewhat  difficult  to  detect  in  small  quantities. 

Besides  the  usual  two-bath  process  of  dj^eing  Cochineal  a  one-bath 
method  may  also  be  used,  as  follows:  The  dj^ebath  is  prepared  with  6 
per  cent  of  oxalic  acid,  G  per  cent  of  stannous  chloride,  and  20  per  cent  of 
Cochineal.  The  oxalic  acid  should  be  added  before  the  tin  crystals,  other- 
wise a  precipitate  of  stannous  oxj-chloride  will  occur  which  will  cause  loss 
of  coloring  matter.  A  deficiency  of  tin  causes  the  color  to  be  dull  and  bluer, 
while  an  excess  of  tin  gives  a  paler  scarlet.  The  one-bath  method  gives 
yellower  and  more  brilliant  shades  than  the  two-bath  process,  though  more 
Cochineal  is  required.  The  presence  of  iron  or  copper  in  the  dyevat  should 
be  avoided,  otherwise  the  scarlet  will  be  much  dulled.  To  obviate  this 
defect  arising  from  the  use  of  copper  steam-pipes  in  the  dyevat  a  piece  of 
clean  tin  should  be  placed  in  the  bath ;  this  prevents  the  copper  from  being 
dissolved.  For  the  production  of  very  yellow  tones  of  scarlet  it  is  necessary 
to  use  some  suitable  yellow  dyestuff  in  connection  with  Cochineal.  Fla- 
vine  was  generally'  employed  for  the  purpose. 

8.  Weld. — This  dyestuff  is  obtained  by  drying  a  small  herbaceous 
herb  of  a  varietj^  of  mignonette,  the  botanical  name  of  which  is  Reseda 


508  THE   MINOR   NATURAL   DYES 

luteola.  This  plant  is  indigenous  to  Europe.  Its  coloring  principle  is 
known  as  luteolin,  C20H14O8,  and  may  be  obtained  as  small  yellow  needles 
of  a  bitter  astringent  taste.  It  was  formerly  employed  in  the  dyeing  of 
wool  and  silk  in  y(>llow  shades,  but  is  not  used  to  any  extent  at  present. 

9.  Persian  Berries. — This  dyestuff  is  also  known  as  yellow  berries,  and 
consists  of  the  fruit  of  the  buckthorn  and  other  species  of  Rhamnus,  the 
principal  and  true  varieties  being  RJiamnus  mmjgdaline,  R.  oleoidcs,  and 
R.  saxatatis.  The  fruit  is  usually  gathered  when  not  quite  ripe  and 
on  drying  gives  small  berries  of  a  peculiar  shriveled  appearance.  The 
best  varieties  come  from  Smyrna  and  AUeppo.  The  color  principle  existing 
in  the  berries  is  a  glucoside  known  as  xanthorhamnin,  ds^Gf,02Q.  Persian 
Berries  are  chiefly  used  in  caUco  printing  for  the  production  of  steam 
yellow  and  orange  colors.*  Persian  Berries  as  they  occur  in  trade  are 
shriveled  in  appearance  and  of  a  yellowish  green  color.  If  too  yellow 
they  are  of  an  inferior  quality,  while  if  brown  or  black,  they  are  valueless, 
being  either  overripe  or  injured  l>y  dampness  or  long  storage.  The  extract 
of  Persian  Berries  is  very  liable  to  ferment  and  so  deteriorate;  when 
freshly  prepared  it  is  of  a  brownish  yellow  color. 

10.  Turmeric. — This  dyestuff  is  the  tuber  or  underground  stem  of  the 
Curcuma  tinctoria,  and  grows  principally  in  China  and  the  East  Indies. 
The  chief  varieties  on  the  market  are  the  Chinese,  Bengal,  Java,  and 
Cochin.  The  coloring  principle  is  known  as  curcuviin.]  It  was  used  as  a 
direct  dye  on  cotton,  wool,  and  silk,  but  may  also  be  dyed  in  conjunction 
with  metallic  mordants.  J  In  preparing  Turmeric,  the  roots  are  dried  and 
ground,  giving  a  bright  orange  powder.  It  is  sometimes  adulterated  with 
starch  and  mineral  matters.  Good  qualities  of  the  roots  should  be  of  a 
dull  waxy  appearance,  the  external  color  being  a  yellowish  gray,  while  on 
fracturing,  the  internal  color  should  be  bright  and  more  orange.    The  ash  of 

*  At  the  present  time  Persian  Berries  are  principally  used  in  the  form  of  extracts. 
On  a  copper  mordant  they  give  olive  shades  that  are  exceedingly  fast  to  light.  With 
different  metallic  mordants  they  j'ield  the  following  colors: 

Chromiiun brown 

Aluminium bright  j^ellow 

Iron dark  olive 

Copper yellow-olive 

Tin orange 

t  The  coloring  matter  may  be  isolated  by  first  extracting  the  ground  root  with 
carbon  disulphide  (to  remove  volatile  oils  and  resins),  and  treating  the  residue  with  dilute 
caustic  soda.  The  solution  so  obtained  is  acidulated  with  hydrochloric  acid  when 
the  dye  is  precipitated  in  the  form  of  yellow  flakes.  It  may  be  further  jjurified  by 
recrystallization  from  ether. 

i  In  dyeing  Turmeric,  a  little  alum  or  acetic  acid  should  be  used,  as  if  the  dyebath  is 
at  all  alkaline  the  fiber  will  not  take  up  the  color.  It  is  also  important  that  the  tempera- 
ture should  not  be  over  140°  F. 


LAC    DYE  509 

Turmeric  should  not  be  more  than  5  to  6  per  cent  and  should  be  examined 
for  common  salt,  which  is  often  added  to  give  the  powder  a  brighter  appear- 
ance. The  best  method  of  valuing  Turmeric  is  to  make  comparative  dye- 
tests  on  umnordanted  woolen  skeins.  The  dyeings  should  be  done  at 
fairly  low  temperatures  as  the  color  becomes  dulled  if  the  temperature  of 
dyeing  is  too  high.* 

11.  Kermes. — This  is  the  product  of  a  female  insect  Coccus  ilicis, 
which  lives  on  a  shrub  Quercus  coccifera,  that  grows  in  tropical  climates. 
Good  qualities  have  a  rich  deep-red  color,  and  are  in  grains  about  the  siz-e 
of  a  pea.  It  was  employed  for  the  same  purposes  as  Cochineal,  but  is 
very  little  used  at  present,  f 

12.  Lac  Dye. — This  is  the  product  of  a  small  insect.  Coccus  lacca,  which 
lives  on  the  twigs  of  the  banyan  (Ficus  religiosa)  and  other  trees  of  the 
genus  Ficus,  which  grow  principally  in  Bengal  and  British  Burma.  The 
coloring  principle  is  laccainic  acid,  Ci6Hi208.  It  was  formerly  employed 
for  the  dyeing  of  scarlet  and  crimson  colors  on  wool.|  The  stick-lac  of  trade 
simply  consists  of  the  twigs  of  the  banyan  tree  which  have  been  coated 
to  the  depth  of  about  j  in.  by  propagation  of  the  insect,  which  are  then 
collected,  dried  and  ground.  Such  a  powder  contains  about  10  per  cent 
of  coloring  matter  and  about  70  per  cent  of  resin.  The  stick-lac  is  treated 
with  water  containing  a  little  alkali,  which  dissolves  out  the  coloring 
matter,  which  is  then  precipitated  from  its  solution  by  the  addition  of 
alum,  and  the  precipitate  is  collected  and  dried.  The  residue  left  after 
treatment  with  water  is  known  as  seed-lac,  which  if  melted  and  filtered 
gives  the  shell-lac  of  trade.  A  good  quality  of  Lac  dye  should  be  soft 
enough  to  be  broken  easily,  and  should  also  powder  readily.  The  lumps 
should  be  homogeneous  and  free  from  resinous  matter.  Samples  that  are 
hard  and  have  a  resinous  appearance  are  usually  of  a  low  and  inferior 

*  Turmeric  is  extensively  used  in  chemical  analysis  as  an  indicator  for  boric  acid,  as 
it  gives  with  this  acid  a  very  characteristic  reaction.  Turmeric  paper  is  filter  paper 
stained  with  a  solution  of  Turmeric.  If  this  be  moistened  with  boric  acid  and  dried  it 
shows  a  brownish  red  color,  and  on  the  addition  of  a  drop  of  caustic  soda  it  turns  blue 
or  green. 

t  In  the  Mediterranean  countries  Kermes  is  still  used  to  some  considerable  extent  for 
the  dyeing  of  leather  and  woolens.  It  is  also  used  by  the  natives  for  dyeing  the  manes 
and  tails  of  horses.  Kermes  is  a  very  ancient  dye,  having  been  used  in  the  East  as  far 
back  as  history  goes.  The  coloring  principle  of  Kermes  is  carminic  acid,  apparently 
identical  with  that  of  Cochineal.  Owing  to  the  fact  that  Kermes  was  formerly  supposed 
to  consist  of  grains,  dyeings  with  Kermes  were  known  as  "  grain  "  or  "  ingrain  "  colors, 
and  this  name  passed  on  to  those  colors  obtained  with  Cochineal,  and  later  to  the  red 
color  obtained  with  Primuline. 

%  This  dye  is  a  by-product  in  the  manufacture  of  shellac,  and  is  still  available  in 
considerable  quantity.  It  is  still  used  extensively  in  India  and  Persia  for  the  dyeing  of 
bright  reds  and  scarlets  on  wool.  It  is  used  very  much  in  the  same  manner  as  Cochineal. 
It  gives  colors  that  are  somewhat  faster  than  Cochineal  but  not  so  bright. 


510  THE   MINOR  NATURAL   DYES 

quality.     The  amount  of  water  in  Lac  dye  should  be  about  10  per  cent  and 
the  ash  al)out  15  per  cent. 

13.  Experimental.  Exp.  188.  Use  of  Fustic. — Mordant  a  test  skein  of  woolen  yarn 
with  3  per  cent  of  chrome  and  4  per  cent  of  tartar  in  the  usual  manner.  Dye  for  forty- 
five  minutes  in  a  bath  containing  10  per  cent  of  Fustic  extract,  entering  at  140°  F'.  and 
gradually  raising  to  the  boil.  Wash  well  and  dry.  Mordant  a  second  skein  with  5 
per  cent  of  stannous  chloride  and  5  per  cent  of  oxalic  acid,  and  dye  in  the  same  manner 
as  above  with  10  per  cent  of  Fustic  extract.  Mordant  a  third  skein  with  6  per  cent  of 
ferrous  sulphate  and  S  per  cent  of  tartar,  and  dye  as  before  with  10  per  cent  of  Fustic 
extract.     Note  the  difference  in  color  obtained  from  the  Fustic  by  the  use  of  different 


FiG.  256.— Three-Cylinder  Back  Drying  Machine.     (Textile-Finishing  Machinery  Co.) 

mordants.  Test  the  fastness  of  the  color  to  washing  and  light,  and  compare  the  results 
with  those  given  by  Alizarine  Yellow.  Mordant  a  fourth  skein  with  chrome  and  tartar 
as  above,  and  a  fifth  skein  w4th  tin  and  oxalic  acid ;  then  dye  with  10  per  cent  of 
Aurantine  powder  (Osage  Orange).  Compare  these  dyeings  wuth  those  obtained 
with  Fustic. 

Exp.  189.  Use  of  Madder. — This  dyestuff  was  formerly  very  extensively  employed 
but  has  now  been  replaced  almost  entirely  by  the  synthetically  prepared  AUzarine,  which 
is  the  coloring  principle  of  Madder.  Madder  consists  of  the  ground  root  of  Rubia 
tinctonnn,  and  is  applied  as  a  mordant  dyestuff.  Mordant  a  test  skein  of  woolen  yarn 
with  3  per  cent  of  chrome  and  4  per  cent  of  tartar,  and  dye  for  forty-five  minutes  in  a 
bath  prepared  by  boiling  2.5  per  cent  of  Madder  in  water  and  straining.  Also  add  4 
per  cent  of  calcium  acetate  to  the  dyebath  This  mordant  yields  a  reddish  brown  color 
with  Madder.  In  a  similar  manner  dye  a  test  skein  which  has  been  mordanted  with 
10  per  cent  of  aluminium  sulphate  and  8  per  cent  of  tartar.     This  mordant  yields  a  dull 


-^  EXPERIMENTAL  STUDIES  511 

red  color.  Dye  a  third  test  skein  mordanted  with  5  per  cent  of  stannous  chloride  and 
5  per  cent  of  oxalic  acid  and  notice  that  an  orange-red  color  is  obtained. 

Madder  may  be  dyed  in  a  single  bath  as  follows:  Prepare  a  bath  containing  5  per  cent 
alum,  4  per  cent  tartar,  10  per  cent  Madder,  and  4  per  cent  calcium  acetate;  enter  cold 
and  slowly  bring  to  the  boil,  dyeing  at  this  temperature  for  one  hour.  This  is  used  only 
for  light  shades,  as  otherwise  there  would  be  coiivsiderable  precipitation  in  the  dyebath. 

Exp.  190.  Use  of  Archil. — This  dye,  together  with  the  related  coloring  matter  Cud- 
bear, is  but  Uttle  used  at  present.  It  possesses  the  character  of  a  substantive  dye  towards 
wool  and  yields  a  dull  magenta  shade.  It  can  be  applied  in  a  neutral  bath,  though  the 
addition  of  acid  makes  the  color  redder  and  brighter.  The  color  is  not  fast  to  light  or 
fulling,  and  only  fairly  so  to  washing.  Dye  a  test  skein  of  woolen  yarn  in  a  neutral  bath 
containing  20  per  cent  of  Archil  paste,  entering  at  120°  F.  and  raising  to  the  boil  for  forty- 
five  minutes.  Dye  a  second  skein  in  a  bath  containing  20  per  cent  of  Archil  paste  and 
4  per  cent  of  sulphuric  acid.  Notice  the  difference  in  the  color  caused  by  the  use  of  the 
acid  in  the  dyebath.  Archil  at  the  present  time  is  not  used  as  a  self  color,  but  in  com- 
bination with  various  acid  dyes  for  the  production  of  browns,  maroons,  and  clarets; 
it  is  also  employed  as  a  bottom  for  Indigo.  It  is  not  used  for  the  dyeing  of  cotton. 
Silk  may  be  dyed  with  Archil  in  a  soap  bath,  with  or  without  the  addition  of  acetic  acid. 

Exp.  191.  Use  of  Quercitron. — This  is  a  yellow  coloring  matter  obtained  from  the 
bark  of  a  species  of  oak.  Quercitron  itself  consists  of  the  ground  bark,  while  Flavine 
is  the  pure  dry  extract  of  the  coloring  matter.  Mordant  a  test  skein  of  woolen  yarn 
with  3  per  cent  of  chrome  and  4  per  cent  of  tartar  in  the  usual  manner,  and  then  dye 
with  10  per  cent  of  Quercitron  bark,  boiling  for  forty-five  minutes.  On  this  mordant 
Quercitron  gives  an  olive-yellow  color.  Mordant  another  test  skein  with  4  per  cent  of 
stannous  chloride  and  2  per  cent  of  oxalic  acid;  remove  the  skein  from  the  mordanting 
bath,  add  1  per  cent  of  Flavine  extract,  boil  up  for  five  minutes,  then  re-enter  the  wool 
and  continue  boiUng  for  forty-five  minutes.  This  method  of  dyeing  should  yield  a 
bright  canary- yellow.  By  increasing  the  amount  of  Flavine  the  color  becomes  orange- 
yellow.  Quercitron  and  its  products  are  but  little  used  for  wool  dyeing  at  present, 
though  they  are  stUl  employed  to  some  extent  in  both  cotton  and  wool  printing.  The 
color  is  not  particularly  fast  to  either  light  or  scouring. 

Exp.  192.  Use  of  Cutch. — This  brown  dyestuff  is  also  a  tannin,  and  in  this  latter 
connection  it  has  already  been  considered.  As  a  dyestuff  it  was  formerly  very  exten- 
sively used  on  cotton,  and  for  the  production  of  certain  tones  of  brown  it  is  still 
employed  quite  largely  in  cotton  dyeing.  It  is  not  used  for  the  dyeing  of  wool,  as  the 
fiber  is  made  too  harsh.  In  silk  dyeing  it  is  largely  used,  but  only  as  a  tannin  in  con- 
nection with  Logwood  black.  Prepare  a  bath  containing  15  per  cent  of  Cutch  and  dye  a 
test  skein  of  cotton  yarn  for  one  hour  at  195  to  210°  F.  Then  squeeze  the  skein  and 
treat  for  thirty  minutes  at  160°  F.  in  a  bath  containing  5  per  cent  of  chrome,  and  finally 
give  a  thorough  washing.  Darker  shades  of  brown  are  obtained  by  the  addition  of  blue- 
stone  to  the  dyebath  as  follows:  Dye  a  test  skein  of  cotton  j'arn  in  a  bath  containing 
15  per  cent  of  Cutch  and  2  per  cent  of  bluestone;  squeeze  and  treat  with  chrome  solution 
as  above. 

Exp.  193.  Dyeing  Wool  with  Cochineal. — The  solution  of  the  coloring  matter  is 
best  prepared  by  boiling  the  cochineal  bugs  in  water  and  straining  the  solution. 

(a)  Mordant  a  test  skein  of  wool  with  3  per  cent  chrome  and  4  per  cent  tartar;  wash, 
and  dye  with  20  per  cent  Cochineal. 

(6)  Mordant  two  test  skeins  of  wool  with  6  per  cent  of  alum  and  4  per  cent  tartar; 
wash,  and  dye  with  20  per  cent  and  10  per  cent  respectivelj^  of  Cochineal.  The  shade 
obtained  is  a  crimson.  A  one-bath  method  may  also  be  used:  Dye  a  test  skein  of  wool 
in  a  bath  containing  6  per  cent  of  alum,  5  per  cent  oxalic  acid,  and  20  per  cent  Cochineal. 
The  crimson  may  be  given  a  bluer  shade  by  adding  a  little  soda  ash  to  the  batb 


512 


THE    MINOR    NATURAL    DYES 


(c)  Mordant  two  test  skeins  of  wool  with  G  per  cent  of  stannous  chloride  and  6 
per  cent  oxalic  acid;  wash,  and  dye  respectively  with  20  per  cent  and  10  per  cent  Cochi- 
neal. The  process  may  also  be  carried  out  in  one  bath,  which  method  in  fact  is  the  most 
used:  Dye  a  test  skein  of  wool  in  a  bath  containing  6  per  cent  stannous  chloride,  G 
per  cent  oxalic  acid,  and  20  per  cent  Cochineal.  The  oxalic  acid  should  be  added  before 
the  stannous  chloride,  otherwise  a  preqipitate  of  stannous  oxychlorido  will  occur  which 
will  cause  loss  of  coloring  matter. 

A  deficiency  of  tin  causes  the  color  to  be  dull  and  bluer,  while  an  excess  of  tin  gives 
a  paler  scarlet.  Instead  of  oxalic  acid,  tartar  may  be  used  as  the  assistant,  an  excess  of 
tartar  giving  a  yellower  tone  to  the  scarlet.  As  a  rule,  a  small  amf)unt  of  yellow  dj'e  is 
used  in  order  to  intensify  the  scarlet.     The  one-bath  method  gives  yellower  and  more 


W^l 


Fig.  257. — Thirty-one  Cylinder  Horizontal  Dryer.       (Textile-Finishing  ^Machinery  Co.) 


brilliant  shades  than  the  two-bath  process,  though  more  Cuchiueal  is  required  to  give  the 
same  shades,  as  in  the  single-bath  method  some  of  the  coloring  matter  remains  in  the 
dyebath  in  combination  with  the  mordant.  The  presence  of  iron  or  copper  in  the  vat.3 
should  be  avoided,  otherwise  the  Cochineal  scarlet  will  be  much  dulled. 

{(I)  Dye  a  test  skein  of  wool  in  a  bath  containing  5  per  cent  tin  nitrate,  4  per  cent 
tartar,  and  20  per  cent  Ammoniacal  Cochineal.  The  mordant  here  given  is  the  one 
which  works  best  with  this  form  of  Cochineal.  Compare  this  color  with  the  one  obtained 
from  ordinary  Cochineal  and  tin  mordant.  A  good  rose  pink  may  be  obtained  as  follows: 
Dye  a  test  skein  of  wool  in  a  bath  containing  2  ])er  cent  Ammoniacal  Cochineal,  2  per 
cent  Cochineal,  4  iier  cent  tin  nitrate,  and  4  percent  tartar.  The  tin  nitrate  may  be 
prepared  by  dissolving  1  part  tin  in  S  parts  nitric  acid. 


CHAPTER   XXII 
THE  MINERAL  DYESTUFFS 

1.  General  Use  cf  Mineral  Dyes. — There  arc  a  few  mineral  com- 
pounds which  are  capable  of  being  used  for  the  dyeing  of  textile  fabrics. 
Though  formerly  of  considerable  importance,  this  class  of  colors  is  now 
nearly  obsolete  in  dyeing.  They  differ  very  radically  from  the  vegetable 
and  coal-tar  colors  in  that  they  are  of  mineral  nature  a.nd  are  not  organic 
bodies.  As  a  rule,  they  are  exceedingly  fast  to  light,  and  are  also  very  fast 
to  washing.  The  general  method  of  dyeing  these  colors  is  to  impregnate 
the  fiber  with  a  solution  of  som^e  metallic  salt,  and  subsequently  to  treat 
it  with  a  solution  of  another  compound  capable  of  jdelding  a  colored  pre- 
cipitate with  the  metal  already  present.  Lead  salts,  for  instance,  when 
added  to  potassimii  bichromate  give  a  bright  yellow  precipitate  of  Chrome 
Yellow  (lead  chromate) ;  if  this  precipitation  is  produced  within  the  fiber 
itself,  then  the  latter  will  become  dyed  with  the  Chrome  Yellow. 

Cotton  is  the  fiber  mostly  used  for  the  application  of  the  mineral  colors, 
the  only  color  which  is  applied  to  wool  being  Prussian  Blue.  All  the  min- 
eral dyes  make  the  fabric  more  or  less  harsh  and  stiff;  this  may  be  reme- 
died somewhat  by  after-soaping,  or  by  using  a  cotton  softener  of  oO,  but 
it  can  never  be  removed  entirely.  ]\Iany  of  the  mineral  compounds  used 
in  the  preparation  of  these  colors  are  of  a  poisonous  nature,  which  is  a  great 
drawback  to  their  use;  lead,  copper,  arsenic,  mercury,  and  antimony 
compounds  are  all  poisonous.  As  many  of  the  metals  forming  the  basis 
of  these  colors  also  serve  as  mordants  with  Alizarine  and  many  acid  dyes, 
the  colors  obtained  with  the  metallic  pigments  may  be  shaded  and  modi- 
fied by  the  use  of  suitable  coal-tar  dyestuffs.  Loose  cotton  is  seldom  dyed 
with  the  mineral  colors,  as  it  then  becomes  difficult  to  card  and  spin. 
The  mineral  colors,  though  now  but  little  used  in  actual  dyeing,  are  still 
employed  rather  exiensively  in  calico-printing.*     In  the  latter  they  are 

*  The  mineral  pigment  dyes  are  still  used  in  the  dyeing  of  window-shade  cloth  and 
awning  cloth,  the  colors  of  which  require  great  fastness  to  light.  Khaki,  which  is 
obtained  by  dyeing  with  Iron  Buff  and  Chrome  Green,  is  largely  used  for  tent  and  tar- 
paulin cloth  for  the  army.  It  was  formerly  much  in  vogue  for  uniform  cloth,  but  was 
abandoned  as  too  harsh  for  comfort  in  wearing.  During  the  recent  war  most  of  the 
khaki  cotton  uniform  cloth  was  dyed  with  sulphur  colors.  The  vat  dyes  are  best  and 
fastest  for  this  purpose,  but  were  not  available  during  the  war. 

513 


514  THE   MINERAL   DYESTUFFS 

used  in  connection  with  albumin  in  the  color  pastes,  and  this  on  steaming 
becomes  coagulated  and  rendered  insoluble,  and  at  the  same  time  serves 
to  fix  the  color  on  the  cloth. 

The  mineral  colors  differ  in  the  principle  of  their  dj'eing  from  that  of  the 
coal-tar  dyes  in  that  they  are  strictly  of  a  pigment  character.  There  is  no 
combination  l^etween  the  coloring  matter  and  the  fiber  itself;  there  is 
only  a  uniform  precipitation  of  the  finely  divided  insoluble  pigment  through- 
out the  cells  of  the  fiber,  caused  by  the  chemical  double  decomposition 
between  the  two  soluble  salts  employed.*  The  metallic  salt  is  absorlx^d 
by  the  fiber  from  its  solution  by  osmosis  into  the  cells  of  the  latter;  as 
the  osmotic  action  is  comparatively  slow,  in  order  that  the  final  dj'eing  be 
thoroughl}^  penetrated,  it  is  ad^"isable  to  allow  the  cotton  to  steep  in  the 
solution  of  the  metallic  salt  for  a  considerable  time,  and  before  being  entered 
in  the  bath  the  yarn  or  cloth  should  be  thoroughly  wetted  out,  else  the 
fiber  will  not  become  complete!}'  impregnated  with  the  salt.  After  thor- 
ough saturation  the  goods  may  even  be  rinsed  in  fresh  water  without  fear 
of  washing  out  the  metallic  salt  held  in  the  pores  or  cells  of  the  fiber;  in 
fact,  a  moderate  rinsing  may  be  considered  beneficial,  as  it  serves  to  remove 
the  excess  of  solution  adhering  to  the  outside  of  the  fibers  and  between  the 
interstices  of  the  fibers  themselves,  as  this  is  not  removed  by  a  simple 
squeezing  or  wringmg.  This  portion  of  the  metalUc  salt  solution  not  held 
osmotically  bj?^  the  fiber  would  come  off  to  a  certain  extent  in  the  succeeding 
bath  wherein  the  pigment  is  formed,  thus  causing  an  unnecessaiy  con- 
sumption of  chemicals,  and  the  contamination  of  the  second  bath  with  a 
precipitate.  There  would  also  be  formed  a  loosely  adherent  precipitate 
of  pigment  in  the  interstices  between  the  fibers,  which  would  not  prove 
fast  to  washing  or  rubbing,  and  in  the  case  of  yarn  would  also  dust  off  in 
the  handUng  thereof,  besides  adding  considerably  and  unnecessarily  to 
the  harshness  of  the  cotton.  The  action  of  the  second  or  precipitating 
solution  is  also  by  osmosis.  Takmg  the  formation  of  Chrome  Yellow  as  an 
example,  the  solution  of  potassium  bichromate  gradually  passes  by  osmosis 
into  the  pores  of  the  fiber,  where  it  comes  in  contact  with  the  lead  acetate 
already  present;  the  insoluble  chromate  of  lead  separates  out,  and  thus 
is  held  securely  in  the  pores  of  the  fiber  while  the  second  member  of  the 
reaction,  the  potassium  acetate,  being  a  soluble  salt,  passes  back  into  the 
bath  again  by  osmosis. 

*  The  so-called  pastel  colors  on  woolen  piece-goods  may  be  considered  as  a  form  of 
mineral  dyestuflf.  These  colors  are  generally  dyed  on  bleached  woolen  pieces  in  the 
rinsing  machine.  For  each  piece  about  6  to  9  lbs.  of  pure  whitening  are  sifted  into  the 
washer  containing  a  minimum  quantity  of  water,  the  pieces  are  run  a  few  times,  then  a 
dyestuflf  solution  is  added,  and  the  pieces  run  for  several  times  cold,  and  finally  rinsed. 
For  the  production  of  pearl-gray  shades  zinc  white  may  be  used  in  place  of  whitening. 
The  following  dyestuffs  are  adapted  to  this  method:  Auramine,  Orange  II,  Rhodamiiic, 
Acid  Violet,  Neptune  Green. 


MINERAL  KHAKI 


515 


Most  of  the  mineral  colors  are  very  cheap  in  their  application,  but  it  is 
rather  difficult  to  dye  them  to  a  matched  shade.  Their  exceptional  fast- 
ness to  light  and  washing  is  their  principal  advantage. 

2.  Mineral  Khaki  on  Cotton.— Khaki  is  a  brown  color  with  a  greenish 
or  drab  tone  which  is  used  very  largely  on  army  cloth  for  various  purposes. 
The  color  is  supposed  to  approximate  that  of  dry  ground  and  so  blend 
in  with  the  country  environment  that  the  object  thus  colored  has  but 
slight  visibility  from  the  distance.     The  name  is  derived  from  an  East 
Indian  term  meaning  "  dirt."     Mineral  khaki  as  dyed  on  cotton  consists 
of  a  mixture  of  the  oxides  of  iron  and  chromium  in  such  proportion  as  to 
furnish  the  desired  color.     There  are  many  different  formulas  in  use  for 
the  production  of  this  color;  one  which  has  proven  very  satisfactory  is  as 
follows:  The  cloth  is  first  scoured  and  then  treated  with  a  solution  standing 
at  36°  Tw.  and  containing  a  mixture  of  the  acetates  of  iron  and  chromium. 
The  chromium  acetate  is  prepared 
by  the  reduction  of  sodium  bichro- 
mate with   glucose   and    sulphuric 
acid  in  the  presence  of  acetic  acid. 
The  solution  is  usually  appHed  in  a 
padding  machine  and  hot  so  as  to 
obtain  good  penetration.     The  cloth 
is  dried  over   hot   cans,  and    then 
steamed  for  four  minutes  in  a  rapid 
ager  where  the  steam   and  air  are 
at  a  temperature  of  220°  F.     After 
steaming    the    goods    are    treated 
with    a    boiling    solution    standing 
at  12°  Tw.  and  containing   1  part 
caustic  soda  and  3  parts  of  soda 
ash.     When  properly  dyed  mineral  khaki  is  a  very  fast  color,  especially  to 
light,  washing,  alkalies,  and  weather  conditions;  it  is  not  fast  to  acids,  which 
dissolve  off  the  iron  oxide. 

3.  The  Minor  Pigment  Colors.— There  are  a  number  of  metaUic  pig- 
ment colors  which  may  be  produced  in  the  fiber  besides  the  ones  which 
have  been  mentioned  in  the  foregoing  pages.  They  are,  however,  of  only 
theoretical  value  and  possess  no  practical  importance  to  the  dyer.  A 
brown  color  may  be  dyed  on  wool  by  working  it  in  a  bath  containing  lead 
acetate  and  Imie;  the  sulphur  present  in  the  wool  combines  to  form  lead 
sulphide.  A  gray  color  on  cotton  may  be  produced  by  working  the  latter 
m  a  bath  containing  mercury  nitrate,  squeezing,  and  passing  through  a 
bath  containing  sodium  sulphide.  Cotton  may  be  dyed  with  red  oxide  of 
lead  by  steeping  in  a  bath  of  lead  acetate  and  then  passing  through  a  bath 
containing  a  mixture  of  caustic  soda  and  chloride  of  lime.     A  blue  color  on 


Fig.  258.— Rolling  Machine. 
(Curtis  &  Marble.) 


516  THE   MINERAL  DYESTUFFS 

cotton  may  be  obtained  by  working  in  a  bath  containing  ammonium 
molybdate  and  developing  in  a  bath  containing  stannous  chloride  and 
hydrochloric  acid.  A  yellow  color  on  cotton  or  wool  may  be  obtained  by 
the  use  of  titanium  salts  (see  the  application  of  these  salts  in  mordanting). 
Cadmium  Yellow  may  be  precipitated  in  cotton  by  first  steeping  in  a  solu- 
tion of  cadmium  nitrate  or  chloride  and  passing  through  a  bath  containing 
sodium  sulphide.  Scheele's  Green  may  be  dyed  by  first  steeping  the  mate- 
rial in  a  solution  of  copper  sulphate,  then  passing  through  a  bath  of  caustic 
soda,  whereb}'  copper  hj-drate  is  formed,  and  finally  treating  with  a  solu- 
tion of  arsenious  acid,  resulting  in  the  formation  of  green  copper  arsenite. 
Another  green  may  be  made  in  the  fil>er  by  steeping  in  a  solution  of  chrome 
alum,  passing  through  a  bath  of  caustic  soda  and  finally  through  a  bath  of 
sodium  arsenite.     Both  of  these  green  colors  are  very  poisonous. 

4.  Experimental.  Exp.  194.  Chrome  Yellow  on  Cotton. — Steep  a  test  skein  of  cotton 
yam  for  thirty  minutes  in  a  cold  bath  consisting  of  a  0  per  cent  solution  (5  grams  per 
100  cc.)  of  lead  acetate.  Squeeze  evenly,  and  pass  into  a  second  bath  consisting  of  a  1 
per  cent  solution  (1  gram  per  100  cc.)  of  chrome;  work  cold  for  thirty  minutes.  Squeeze 
and  wa.sh  in  fresh  water,  then  soften  by  working  in  a  dilute  solution  of  a  cotton  softener 
or  gh'cerin  and  soap.  Finally  squeeze  and  dr>'.  In  order  to  obtain  heavier  colors  the 
alternate  passages  through  the  baths  of  lead  acetate  and  chrome  may  be  repeated  several 
times.  In  place  of  using  the  ordinary'  acetate  of  lead  (sugar  of  lead)  the  subacetate  is 
preferred  by  some.  This  is  prepared  by  boiling  together  10  parts  of  lead  acetate  and 
6  parts  of  litharge  (lead  o.xide)  with  40  parts  of  water;  filter,  and  use  the  liquor  so 
obtained,  diluting  in  accordance  with  the  depth  of  color  desired.* 

Chrome  Yellow  is  formed  in  accordance  with  the  following  reactions: 

2Pb(C2H302)2+K2Cr207+H20  =  2PbCr04+2HC2H302. 

Lead  Acetate  Chrome  Lead  Chromate       Acetic  Acid 

Chrome  Yellow  may  be  applied  to  wool,  silk,  or  any  other  fiber  in  the 
same  manner  as  above  described  for  cotton,  but  it  is  seldom  if  ever  used  on 
these  fibers.  In  the  dyeing  of  Chrome  Yellow  it  is  necessary'  to  first  apply 
the  lead  salt  and  then  the  chrome;  if  the  reverse  procedure  is  followed  the 
pigment  will  be  precipitated  on  the  outside  of  the  fibers  in  a  loosely  adherent 

*  The  following  method  has  been  recommended  for  d\-eing  Chrome  Yellow  in  prac- 
tice: Prepare  a  stock  liquor  by  boiling  100  lbs.  of  brown  sugar  of  lead  and  50  lbs.  of 
htharge  with  18  gallons  of  water,  and  allow  to  settle;  the  liquor  should  stand  at  125° 
Tw.  Give  the  yam  a  passage  through  lime  water  (1$°  Tw),  WTing  and  then  work  in 
lead  salt  bath  prepared  by  diluting  the  stock  liquor  with  cold  water  to  10°  Tw.;  wring, 
and  pass  through  lime  water  d^"  Tw.)  again.  The  lead  bath  may  be  usedcontinuou.sly, 
being  freshened  up  by  additions  of  the  stock  liquor.  Next  prepare  a  chrome  bath  con- 
taining 6  lbs.  of  sodium  bichromate  per  100  gallons.  Pass  the  j-arn  through  the  chrome 
bath,  and  then  rin.se  by  gi\'ing  a  few  turns  in  water  containing  1  part  of  h\"drochloric 
acid  to  300  parts  of  water.  Finally  wash  well  and  dry.  The  chrome  bath  may  also  be 
used  continuously,  being  freshened  up  from  time  to  time  with  additions  of  chrome  solu- 
tion. Some  recommend  the  addition  of  12  ozs.  of  zinc  sulphate  to  the  chrome  bath  in 
order  to  improve  the  quality  of  the  color. 


D^'EING   CHROME  COLORS  517 

condition,  and  will  not  be  fast  to  washing.  In  dyeing  heavy  shades,  in 
order  to  get  the  most  even  results  and  the  fastest  color,  it  is  best  not  to 
use  more  concentrated  solutions  but  to  give  the  cotton  several  dips  suc- 
cessively in  the  two  solutions  until  the  desired  depth  of  shade  is  obtained.* 
To  obtain  the  purest  shades  of  yellow,  it  is  l^cst  to  have  the  chrome  bath 
slightly  acid,  for  if  the  latter  becomes  at  all  alkaline  the  resulting  pigment 
will  acquire  an  orange  tone.  On  this  account  it  is  better  to  employ  the 
bichromate  of  potash  rather  than  the  neutral  chromate.  Chrome  Yellow, 
though  extremely  fast  to  light,  washing,  and  acid,  is  quite  sensitive  to  the 
action  of  sulphuretted  hydrogen,  turning  dark,  owing  to  the  formation 
of  black  lead  sulphide.  As  the  air  of  cities,  especially  in  the  vicinity  of 
factories,  and  the  air  of  houses  heated  by  burning  coal,  always  contains 
more  or  less  sulphuretted  hydrogen,  this  accounts  for  the  gradual  darkening 
of  Chrome  Yellow  on  exposure.  This  discoloration  can  be  prevented  to  a 
considerable  extent  by  incorporating  with  the  lead  salt  a  salt  of  zinc  or 
cadmiimi,  the  sulphide  of  the  former  being  white  and  that  of  the  latter 
yellow  in  color. 

Exp.  195. — In  order  to  show  this  action,  add  to  the  bath  of  lead  acetate  used  in  the 
above  experiment  1  per  cent  of  cadmium  nitrate;  then  dye  a  second  skein  of  cotton  in 
the  same  manner  as  the  previous  one.  Take  small  samples  of  the  two  skeins  and  place 
them  in  a  bottle,  the  air  of  which  contains  a  minute  quantity  of  sulphureted  hj^drogen. 
After  some  time  it  will  be  found  that  the  first  sample,  dyed  with  the  lead  salt  alone,  has 
become  perceptibly  darkened,  whereas  the  second  sample,  containing  the  addition  of 
cadmium  salt,  is  not  altered.  Though  unaffected  by  acids,  Chrome  Yellow  is  changed 
to  an  orange  by  the  action  of  alkalies;  even  lime  water  will  serve  this  purpose.  The 
orange  color  is  due  to  the  formation  of  a  basic  compound  of  lead  chromate.  To  illus- 
trate this  action,  take  a  small  sample  from  the  skein  dyed  with  Chrome  Yellow  and  boil 
it  in  a  weak  solution  of  soda  ash ;  then  wash  and  dry.  It  will  be  found  to  have  changed  to 
an  orange  color.  Treatment  with  acid  will  in  turn  destroy  the  orange  tone  and  restore 
the  original  yellow  color;  this  may  be  shown  by  steeping  the  sample  above  tested  in  a 
dilute  solution  of  sulphuric  acid,  when  the  color  of  the  original  Chrome  Yellow  will  again 
be  formed. 

By  the  action  of  strong  caustic  alkalies.  Chrome  Yellow  may  be  com- 
pletely discharged  or  dissolved  from  the  fiber,  as  may  be  shown  by  taking 
a  small  sample  from  the  skein  dyed  with  this  color  and  boiUng  it  in  a  solu- 
tion of  caustic  soda,  when  it  will  be  found  to  become  rapidly  decolorized. 
This  reaction  is  very  useful  in  printing,  as  b}'  its  means  discharge  effects 
may  be  obtained. 

Exp.  196.  Chrome  Orange  on  Cotton. — As  already  indicated  in  the  previous  experi- 
ment, this  color  may  be  obtained  by  forming  the  basic    chromate  of  lead  in  the  fiber 

*  Yarn  dyed  with  Chrome  Yellow  is  quite  heavily  weighted,  the  increase  in  weight 
sometimes  amounting  to  as  much  as  40  per  cent,  and  sometimes  this  is  of  advantage. 
There  are  limitations  on  the  use  of  Chrome  Yellow,  however,  on  account  of  its  poisonous 
character,  the  dust  from  materials  dyed  with  it  being  injurious  to  the  health  of  the 
workmen. 


518  THE   MINERAL   DYESTUFFS 

by  the  use  of  lead  chromate  and  an  alkali.  Proceed  as  follows:  Work  a  test  skein  of 
cotton  yarn  for  thirty  minutes  in  a  cold  bath  consisting  of  a  5  per  cent  solution  of  lead 
acetate;  squeeze,  antl  jiass  into  a  second  bath  consisting  of  a  1  per  cent  solution  of  chrome 
and  a  small  quantity  of  caustic  soda.  Enter  cold  and  gradually  raise  to  the  boil  for  a  few 
minutes.     Wash  in  a  warm  dilute  soap  bath. 

A  modification  of  the  above  method  is  to  use  the  basic  acetate  of  lead  prepared  in  the 
manner  prescribed  in  the  previous  experiment  from  lead  acetate  and  litharge. 

The  Clirome  Orange  obtained  as  above  indicated  may  be  brightened  somewhat  by 
working  in  a  boiling  bath  containing  lime.  Dye  a  second  skein  of  cotton  in  a  manner 
similar  to  the  first,  repeating  the  treatment  in  the  two  baths  three  times.  Squeeze 
and  wash,  then  work  for  fifteen  minutes  at  the  boil  in  a  bath  containing  10  per  cent  of 
lime  (quicklime).     Finally  wash  and  soap  as  before. 

B}'  a  stronger  or  weaker  treatment  with  alkali,  Chrome  Orange  may  be 
made  to  vary  in  shade  from  a  bright  yellowish  orange  to  a  soarlet-rcd 


Fig.  259. — Automatic  Clip  Tenter.     (Textile-Finishing   Machinery   Co.) 

The  remarks  made  under  Chrome  Yellow  as  to  its  fastness  and  reactions 
with  various  agents  are  also  applicable  to  Chrome  Orange. 

Both  Chrome  Yellow  and  Chrome  Orange  are  poisonous  substances, 
and  may  give  rise  to  cases  of  poisoning  among  operatives  handUng  cotton 
dyed  in  this  manner,  or  even  to  wearers  of  such  fabrics.  These  dye  may 
be  tested  for  on  the  fiber  by  boiung  a  sample  in  caustic  soda  solution  and 
then  adding  a  few  drops  of  ammonimn  sulphide  solution,  when  a  black 
precipitate  of  lead  sulphide  will  be  formed. 

Exp.  197.  Iron  Buif  on  Cotton. — This  color  is  produced  by  precipitating  a  hydrated 
oxide  of  iron  (FeaOj  -1120)  in  the  fiber.  Proceed  as  follows:  Work  a  test  skein  of  cotton 
yarn  for  thirty  minutes  in  a  cold  bath  consisting  of  a  5  per  cent  solution  of  copperas 
(ferrous  sulphate,  FeS04).  Squeeze,  and  pass  into  a  bath  containing  5  per  cent  on  the 
weight  of  the  cotton  of  soda  ash;  work  for  fifteen  minutes  at  180°  F.  Wash  and  pass 
through  a  warm  dilute  soap  bath.     The  reaction  takes  place  as  follows: 

2FeS04-|-2Na2C03+0  =  Fe.Os-f  2Na2S04-|-C02. 


IRON   COLORS  ON   COTTON  519 

The  oxidation  of  the  iron  from  tlie  ferrous  to  the  ferric  condition  is  effected  by  the 
atmospheric  oxygen.  By  repeating  the  treatment  with  the  two  baths  several  times 
heavier  shades  of  brown  may  be  obtained.  Instead  of  using  copperas  a  solution  of 
"nitrate  of  iron"  (ba.sic  ferric  sulphate)  may  be  substituted,  or  a  solution  of  ferric 
chloride.  Another  method  of  procedure  is  as  follows:  Work  a  skein  of  cotton  as  above 
in  the  same  bath  of  copperas ;  squeeze,  and  pass  through  a  cold  weak  solution  of  chloride 
of  lime  containing  a  little  caustic  soda  for  ten  minutes.  Squeeze,  and  repeat  the 
passage  through  the  two  baths  twice.  This  should  give  quite  a  heavy  shade  of  brown. 
Wash  well,  and  soap  as  before.  The  chloride  of  hme  oxidizes  the  ferrous  salt  very  rapidly 
to  the  ferric  condition;  it  also  forms  a  certain  amount  of  oxy cellulose  with  the  cotton 
which  takes  up  the  iron  compound  more  energetically  than  the  unmodified  cotton. 
Another  method  Of  producing  Iron  Buff  on  cotton  is  to  impregnate  the  material  with  the 
solution  of  the  iron  salt  as  before,  then  to  pass  it  through  a  bath  containing  milk-of-lime, 
after  which  it  is  squeezed  and  exposed  to  the  air  overnight.  This  latter  operation  is 
termed  "  ageing." 

The  light  brown  shade  obtained  with  iron  oxide  is  also  known  as 
nanking  and  chamois.  The  brown  color  of  the  natural  Nanking  cotton  is 
said  to  be  due  to  its  containing  oxide  of  iron  though  this  view  is  subject  to 
some  doubt.  Iron  Buff  on  cotton  is  exceedingly  fast  to  light,  washing,  and 
alkalies,  and  also  to  exposure;  it  is  decolorized,  however,  with  acids,  which 
may  be  shown  by  steeping  a  small  sample  of  the  dyed  skein  in  a  warm  dilute 
solution  of  hydrochloric  acid.  In  calico  printing  Iron  Buff  may  be  dis- 
charged white  with  citric  acid  or  with  a  solution  of  stannous  chloride  in 
hydrochloric  acid. 

As  iron  oxide  forms  a  good  mordant  with  the  Alizarine  and  natural 
dyestuffs,  Iron  Buff  on  cotton  may  be  topped  off  with  these  dyestuffs 
and  quite  an  extensive  variety  of  shades  produced  thereby. 

Exp.  198.  In  order  to  illustrate  this  procedure,  dye  three  skeins  of  cotton  a  light 
shade  of  Iron  Buff  in  the  manner  above  indicated.  Top  off  the  first  one  in  a  bath  con- 
taining 2  per  cent  Alizarine  Red,  the  second  one  with  2  per  cent  Alizarine  Blue,  and 
the  third  one  with  5  per  cent  Fustic  extract  (solid) .  Enter  at  a  low  temperature  and 
gradually  raise  to  the  boil.     Wash  and  soap  in  the  manner  before  described. 

Exp.  199.  Iron  Gray  on  Cotton. — This  color  is  obtained  by  precipitating  tannate  of 
iron  within  the  fiber.  Proceed  as  follows:  Work  a  skein  of  cotton  for  thirty  minutes  in  a 
cold  bath  of  nitrate  of  iron  at  2°  Tw.;  squeeze,  and  pass  into  a  bath  containing  5  per 
cent  of  tannic  acid;  work  cold  for  fifteen  minutes.  Wash  and  soap  in  the  usual  manner. 
Deeper  shades  of  gray  and  slate  may  be  obtained  by  repeating  the  treatment  several 
times.  The  operations  may  also  be  reversed  and  the  treatment  with  the  tannic  acid 
may  take  place  first,  as  in  the  usual  manner  of  mordanting  cotton  for  the  purpose  of 
dyeing  heavy  colors  with  the  basic  dyes.  Besides  tannic  acid  itself  the  various  natural 
tannins  may  be  employed,  such  as  sumac,  cutch,  chestnut  extract,  etc.,  in  which  cases 
the  resulting  color  will  be  modified  by  the  addition  of  the  natural  color  of  the  tannin. 
By  using  rather  concentrated  baths  and  repeating  the  operations  several  times,  cotton 
may  be  dyed  black  by  this  method.  In  fact,  before  the  introduction  of  Logwood,  this 
was  the  chief  method  for  the  dyeing  of  black  on  cotton . 

Iron  Gray  on  cotton  is  quite  fast  to  light  and  washing;  on  long  exposure 
it  turns  rusty,  owing  to  the  gradual  formation  of  iron  oxide;  it  also  turns 


520  THE   MINERAL  DYESTUFFS 

brown  on  treatment  with  alkalies  for  the  same  reason.     Like  Iron  Buff  it  is 
also  decolorized  by  the  action  of  acids. 

Exp.  200.  Manganese  Brown  on  Cotton. — This  color  is  also  known  as  "  Bistro," 
and  is  formed  bj'  precipitating  an  oxide  of  manganese  in  the  fiber.  Proceed  as  follows: 
Work  a  skein  of  cotton  for  thirty  minutes  in  a  cold  bath  consisting  of  a  5  per  cent  solu- 
tion of  manganese  chloride;  squeeze  and  pass  into  a  cold  bath  containing  10  per  cent  of 
caustic  soda;  work  for  fifteen  minutes;  wash  in  fresh  water,  and  then  pass  into  a  dilute 
bath  of  chloride  of  lime  (about  1°  Tw.);  finally  wash  well  and  soap  in  the  usual  manner. 

In  the  treatment  with  caustic  soda  there  is  precipitated  in  the  fiber  a 
hydrate  of  manganese;  a  dilute  bath  of  soda  ash  may  also  be  used  for  the 
same  purpose.  The  final  treatment  with  chloride  of  lime  is  for  the  purpose 
of  oxidizing  the  compound  to  the  higher  oxide  of  manganese.  The  result- 
ing compound  is  prol^ably  MnoOs  and  consists  of  a  mixture  of  manganese 
dioxide,  MnOo,  and  manganous  oxide,  ]\InO.  Bistre  was  formerly  a  very 
important  color  for  cotton  and  extensively  used  both  in  dyeing  and  print- 
ing. It  is  verj^  fast  to  light,  washing,  and  alkalies;  it  is  also  fast  to  dilute 
acids  but  strong  acids  decolorize  it,  as  also  do  reducing  agents. 

Bistre  may  also  be  dyed  on  cotton  by  passing  the  material  saturated 
with  the  solution  of  manganese  chloride  into  a  bath  containing  a  mixture 
of  caustic  soda  and  chloride  of  lime,  an  operation  which  then  dispenses 
with  the  use  of  a  third  bath.  The  use  of  soda  ash  in  place  of  the  caustic 
soda  cannot  be  recommended,  as  the  precipitate  produced  contains  man- 
ganese carbonate,  which  is  not  as  readily  oxichzed  as  the  hydrate.  The 
final  dyeing  is  also  apt  to  come  out  rather  uneven. 

Exp.  201. — Bistre  can  also  be  produced  on  cotton  by  the  use  of  potassium  perman- 
ganate, as  may  be  shown  in  the  following  manner:  Work  a  skein  of  cotton  for  fifteen 
minutes  in  a  cold  bath  containing  2  per  cent  of  potassium  permanganate.  The  cotton 
will  be  found  to  turn  brown  rapidly  on  exposure  to  the  air;  squeeze,  wash,  and  soap  in 
the  usual  manner. 

Manganese  BrowTi  is  decolorized  by  treatment  with  either  hydrogen  peroxide  or 
sulphurous  acid;  wherein  it  differs  from  the  brown  obtained  from  iron  oxide.  In  order 
to  show  this  behavior,  take  a  small  sample  each  of  Iron  Buff  and  Bistre  and  steep  them 
for  several  hours  in  a  solution  of  hydrogen  peroxide;  also  steep  two  similar  samples  in  an 
acidified  solution  of  sodium  bisulphite.  It  will  be  found  that  the  samples  of  Bistre  are 
more  or  less  completelj'  decolorized,  while  the  samples  of  Iron  Buff  are  not  much  altered. 

Bistre  may  be  employed  as  the  basis  for  the  production  of  Aniline  Black  on  cotton, 
proceeding  as  follows:  Take  a  skein  of  cotton  dyed  a  full  shade  of  brown  with  Bistre 
in  the  manner  above  described,  and  work  it  in  a  cold  bath  containing  10  per  cent  of 
aniline  salt;  then  gradually  bring  to  the  boil.  Squeeze,  wash  thorough!}',  and  soap  in 
the  usual  manner.  This  black  is  very  fast  to  washing.  By  using  paraphenylene-diamine 
or  beta-naphthylamine,  a  very  good  shade  of  brown  may  be  obtained  which  does  not 
differ  much  in  color  from  the  original  Bistre,  but  it  is  fast  to  acids.  With  alpha-naph- 
thylamine  a  plum  color  is  produced. 

Cotton  cloth  dyed  with  Bistre  has  the  property  when  subsequently 
dyed  in  the  Indigo  vat  of  taking  up  a  greater  amount  of  Indigo  and  fixing 


MANGANESE   COLORS 


521 


it  faster  to  washing  than  ordinary  cotton.  Bistre  is  sometimes  used  in 
dyeing  of  mohair  phish  in  order  to  give  a  fabric'  in  imitation  of  a  natural 
fur  pelt,  the  cotton  back  being  dyed  with  Cutch  brown  in  the  yarn,  while 
the  mohair  pile  is  woven  from  undyed  yarn.  The  plush  is  then  treated 
with  a  solution  of  potassium  permanganate,  which  rapidly  dyes  the  mohair 
brown  and  also  colors  the  cotton  back  a  fuller  shade.  As  soon  as  the 
desired  shade  is  obtained  the  material  is  washed  and  dried.  Then  by  the 
use  of  rotating  brushes  a  suitably  thickened  solution  of  socUum  bisulphide 
is  applied  to  the  ends  of  the  mohair  pile,  which  causes  the  brown  color  to 
become  discharged,  and  thereby  imitate  more  closely  the  appearance  of  the 
natural  pelt. 


Fig.  260. — Dryer  for  Dyed  Cones.     (Philadelphia  Drying  Machine  Co.) 

Exp.  202. — In  order  to  show  the  use  of  Bistre  on  woolen  material,  take  a  skein  of 
wool  and  pass  it  through  a  cold  bath  containing  2  per  cent  of  potassium  permanganate; 
work  for  fifteen  minutes;  then  squeeze  and  wash  well. 

According  to  certain  chemists,  the  irregularity  which  sometimes  arises 
in  dyeing  Manganese  Brown  is  due  to  the  physical  condition  of  the  precip- 
itate itself.  In  order  to  overcome  such  defects,  it  has  been  recommended, 
after  impregnating  the  cotton  with  the  manganese  salt,  to  pass  it  through 
a  bath  containing  ammonia  and  potassium  bichromate,  whereby  a  rather 
unstable  manganese  chromate  is  precipitated  in  the  fiber;  this  gradually 
decomposes,  and  the  chromic  acid  liberated  reacts  with  manganous  hydrate, 
forming  the  higher  oxide  of  manganese.  The  oxidation  is  completed  by 
passing  the  cotton  through  a  dilute  bath  of  bleaching  powder. 

Exp.  203.  Chrome  Green  on  Cotton. — A  pale  dull  shade  of  green  can  be  obtained  on 
cotton  by  precipitating  on  the  fiber  oxide  of  chromium,  Cr20j.     Proceed  as  follows: 


522  THE   MINERAL   DYESTUFFS 

Work  a  test  skein  of  cotton  for  thirty  minutes  in  a  cold  bath  consisting  of  a  10  per  cent 
solution  of  chrome  alum;  squeeze,  and  pass  into  a  bath  containing  10  per  cent  of  soda 
ash;  enter  cold  and  gradually  bring  to  the  boil.  Wash  well  and  soap  in  the  usual 
manner.     By  repeating  the  operations  several  times  fuller  shades  may  be   obtained  .* 

Chromium  oxide  gives  a  sea-green  color  on  cotton  which  is  exceecUngly 
fast  to  Hght,  washing,  and  alkahes;  it  is  also  fast  to  exposure,  but  is  decol- 
orized bj^  the  action  of  acids.  The  color  of  Chrome  Green  may  be  bright- 
ened somewhat  by  passing  the  dyed  cotton  through  a  bath  of  dilute  copper 
sulphate  (the  bath  should  be  very  dilute  and  warm).  Chrome  Green  is 
seldom  used  at  the  present  time  as  a  self  color  on  cotton,  but  it  has  had 
extensive  use  in  conjunction  with  Iron  Buff  for  the  production  of  the  so- 
called  khaki  color  with  which  the  heavy  cotton  goods  of  the  army  are  dyed. 

Exp.  204. — In  order  to  obtain  this  khaki  color  proceed  as  follows:  Work  a  test  skein 
of  cotton  in  a  cold  bath  consisting  of  a  5  per  cent  solution  of  ferric  chloride  with  a  5  per 
cent  solution  of  chrome  alum,  then  pass  into  a  bath  containing  10  per  cent  of  soda  ash; 
enter  cold  and  gradually  bring  to  the  boil.  Wash  well,  and  soap  as  usual.  By  varying 
the  relative  amounts  of  iron  and  chromium  salts,  or  by  the  addition  of  a  small  amount 
of  manganese  salt,  the  shade  of  this  khaki  color  may  be  varied  in  order  to  obtain  any 
tone  desired. 

Exp.  205.  Prussian  Blue  on  Cotton. — The  production  of  this  color  depends  on  the 
precipitation  of  a  ferrocyanide  of  iron  within  the  fiber.  On  cotton  it  is  dj^ed  as 
follows:  \\'ork  a  test  skein  of  cotton  in  a  boiling  bath  of  nitrate  of  iron  (32°  Tw.)  also 
containing  5  per  cent  of  stannous  chloride;  steep  for  thirty  minutes,  squeeze,  and  pass 
into  a  bath  containing  10  per  cent  of  potassium  ferrocyanide  (yellow  prussiate  of  potash) ; 
work  warm  for  fifteen  minutes;  then  pass  back  into  the  bath  of  nitrate  of  iron  again; 
finally  squeeze,  wash,  and  soften  in  a  soap  bath. 

Heavier  shades  may  be  obtained  by  repeating  these  operations  several  times;  the 
cotton,  however,  should  always  be  worked  last  in  the  bath  of  nitrate  of  iron  in  order  to 
prevent  the  formation  of  a  .soluble  variety  of  Prussian  Blue. 

Exp.  206.  Prussian  Blue  on  Wocl. — For  dyeing  wool  proceed  as  follows :  Work  a  test 
skein  of  wool  in  a  bath  containing  10  per  cent  of  potassium  ferricj'anide  (red  prussiate 
of  potash),  20  per  cent  of  sulphuric  acid,  and  1  per  cent  of  stannous  chloride;  enter  cold 
and  gradually  raise  to  the  boil,  when  the  wool  will  turn  green  and  finally  become  blue. 
After  boiling  for  ten  minutes,  lift,  and  add  1  per  cent  more  of  stannous  chloride,  and 
work  for  fifteen  minutes  longer.  Finally  wash  well  in  fresh  water.  The  depth  of  shade 
may  be  varied  by  employing  greater  or  less  amounts  of  potassium  ferricyanide.  If 
the  blue  color  does  not  develop  properly  a  few  drops  of  nitric  acid  may  be  added  to 
the  bath  for  the  purpose  of  accelerating  the  oxidation.     Another  method  of  dyeing  this 

'  A  color  known  as  Chrome  Green  is  sometimes  dyed  on  cotton  by  topping  a  light 
shade  of  Indigo  Blue  with  a  Chrome  Yellow.  It  is  a  color,  however,  which  has  not  much 
use  at  the  present  time  except  for  window-shade  material  and  awning  cloth.  A  Chrome 
Green  can  also  be  obtained  by  precipitating  chromium  hydrate  or  oxide  in  the  fiber 
but  this  only  gives  a  hght  shade  of  sea-green.  Before  the  discovery  of  the  coal-tar 
green  dj^es,  it  was  customary  to  use  chromium  arsenite  as  j^roduced  on  the  fiber  by  the 
interaction  of  chrome  and  arsenite  of  soda.  This  gave  a  rather  rich  and  fast  shade  of 
green,  but  it  was  very  poisonous  and  at  the  present  time  is  not  used  at  all.  Wall-paper 
was  frequently  dyed  green  in  this  manner  (or  printed)  and  many  cases  of  arsenical  poison 
were  traced  to  this  pigment.     Its  use  for  this  purpose  is  now  forbidden. 


PRUSSIAN   BLUE  523 

color  on  wool  is  to  use  15  to  20  per  cent  of  potassium  ferrocyanide  with  the  addition 
of  a  small  amount  of  alum  and  tartar  to  the  bath. 

Prussian  Blue  also  goes  by  the  name  of  Berlin  Blue;  it  was  formerly  a 
very  important  color,  both  for  cotton  and  wool,  and  is  even  still  used  to  a 
consideral^le  extent,  especially  in  printing.  Before  the  introduction  of 
Alizarine  Blue  it  was  extensively  employed  for  the  dyeing  of  army  uniforms. 
Prussian  Blue  appears  to  be  a  complicated  cyanogen  compound  of  iron,  the 
exact  tone  of  which  varies  considerably'  with  the  manner  of  its  production. 
Though  not  now  employed  as  a  self  color  in  dyeing  of  silk,  Prussian  Blue, 
however,  is  still  used  as  a  bottom  color  in  the  dyeing  of  weighted  black  on 
this  fiber. 

Prussian  Blue  is  fast  to  light,  washing,  and  exposure ;  it  is  also  fast  to 
dilute  acids,  but  is  dissolved  by  stronger  acids,  also  bj^  a  concentrated 
solution  of  oxalic  acid.  With  caustic  alkali  it  is  decomposed  into  potas- 
simn  ferrocyanide  and  brown  oxide  of  iron.  This  latter  reaction  is  still 
used  for  discharge  work  in  printing.  The  action  of  stannous  chloride 
in  the  dyeing  of  Prussian  Blue  is  to  brighten  and  give  a  reddish  tone  to 
the  shade,  probably  due  to  the  formation  of  a  tin  ferrocyanide. 

Exp.  207. — A  bright  green  color  on  cotton  may  be  produced  by  the  combined  and 
simultaneous  use  of  Prussian  Blue  and  Chrome  Yellow  in  the  following  manner:  Work  a 
test  skein  of  cotton  in  a  cold  bath  containing  10  per  cent  of  ferrous  acetate  and  10  per 
cent  of  lead  acetate  for  thirty  minutes;  squeeze,  and  pass  into  a  bath  containing  5 
per  cent  of  potassium  ferrocyanide  and  2  per  cent  of  potassium  bichromate.  Squeeze, 
wash  weU,  and  soap  as  usual. 

Boiling  soap  solutions  decompose  Prussian  Blue,  leaving  the  brown 
oxide  of  iron  on  the  fiber.  On  prolonged  exposure  to  sunlight,  the  color 
becomes  somewhat  hghter,  but  the  original  tone  is  restored  on  being  kept 
in  the  dark  for  some  time. 

The  theory  of  the  application  of  Prussian  Blue  to  wool  is  that  when  a 
mineral  acid  is  added  to  a  solution  of  potassium  ferricyanide,  the  corre- 
sponding hydro-ferricyanic  acid  is  Uberated;  this  under  the  influence  of 
heat  and  oxidation  is  decomposed  with  the  precipitation  of  Prussian  Blue. 
If  nitric  acid  is  employed  in  the  bath,  the  shade  of  blue  is  somewhat 
greener  than  when  the  other  mineral  acids  are  used.  Yellow  prussiate  cf 
potash  may  be  used  instead  of  the  red,  in  which  case  it  was  the  custom  of 
dyers  to  use  a  mixture  of  the  three  mineral  acids,  under  the  name  of  "  royal 
V)lue  spirits,"  or  simply  "  blue  spirits."  Nitric  acid  is  the  best  acid  to 
emploj^  in  connection  with  potassium  ferrocyanide  on  account  of  its  oxi- 
dizing action.  The  stannous  chloride  was  formerly  used  b}^  the  dyer  in 
the  form  of  a  solution  known  as  "  muriate  of  tin  "  or  "  finishing  blue 
spirits."  The  solution  in  this  form  often  contained  sulphuric  and  oxalic 
acids. 


CHAPTER    XX 
DYEING  OF  FABRICS  CONTAINING  MIXED  FIBERS 

1.  Character  of  Material. — There  are  a  number  of  fabrics  which  are 
made  up  of  mixed  fibers;  that  is  to  say,  instead  of  being  composed  entirely 
of  wool  or  cotton  or  silk  as  the  case  may  be,  they  contain  two  or  more  of 
these  fibers  together.  ISIost  frecjuently  the  warp  is  made  of  yarn  from  one 
kind  of  fiber  while  the  filling  is  made  of  yarn  of  a  different  fiber,  though 
in  some  cases  the  two  fibers  maj'  be  mixed  in  the  same  yarn.  The  most 
important  of  these  materials  may  be  grouped  as  follows: 

(a)  Wool-cotton  fabrics,  known  as   "union    goods"  or  "  half -wool  ' 
goods. 

(b)  Wool-silk  fabrics,  known  chieflj-  as  "  gloria." 

(c)  Silk-cotton  fabrics,  such  as  ribbons,  satins,  etc. 

In  place  of  cotton  we  may  also  have  artificial  silk  or  mercerized  cotton 
or  linen;  in  place  of  wool  we  may  have  mohair  or  other  animal-hair  fiber. 

It  is  sometimes  required  to  dye  these  goods  in  a  sohd  color;  that  is  to 
say,  both  classes  of  fibers  are  to  be  the  same  shade.  In  other  cases  two- 
color  effects  are  desired;  that  is  one  fiber  is  ch'ed  one  color  and  the  other 
fiber  another  color.  As  each  kind  of  fiber  reacts  somewhat  differently 
with  the  various  dyes  and  the  many  chemicals  employed  by  the  dyer,  and 
as  different  methods  of  application  must  ])e  considered,  deperding  on  the 
nature  and  character  of  the  material,  it  will  be  reahzed  that  the  dj-eing  of 
goods  of  niLxed  fibers  entails  processes  quite  different  from  those  used  in 
the  dyeing  of  fabrics  where  only  one  kind  of  fiber  is  concerned. 

The  use  of  mixed  fabrics  is  on  the  increase,  and  they  are  being  adapted 
to  many  classes  of  goods  both  for  wearing  apparel  and  for  general  fabric 
use.  Consequently  the  application  of  dyes  to  mixed  fibers  has  come  to  be  a 
very  important  branch  of  dyeing,  and  the  properties  of  the  various  dyes 
with  reference  to  their  use  in  this  connection  has  been  carefully  studied. 

2.  Fabrics  of  Wool-cotton  or  Union  Goods  — Fabr  cs  of  wool-cotton 
materials  are  to  be  met  in  different  stages  of  manufacture  and  while  their 
treatment  as  far  as  dyestuffs  is  concerned  is  more  often  in  the  form  of  the 
woven  fabric,  yet  there  are  instances  where  the  material  comes  to  the  dyer 
in  the  form  of  yarn  or  even  in  a  form  intermediate  to  that  of  the  spun  yarn 
itself. 

524 


WOOL-COTTON   FABRICS 


525 


Fabrics  consisting  of  various  mixtures  of  wool  and  cotton  yarns  or 
fibers  are  frequently  known  as  "  union  "  goods,  although  the  exact  desig- 
nation of  the  fabric  or  material  will  vary  with  the  character  of  the  goods 
or  the  usages  of  the  trade  in  which  they  are  current.  For  example,  in 
knit-goods  for  the  underwear  trade,  a  yarn  composed  of  a  mixture  of  wool 
and  cotton  fibers  is  common  y  known  as  '  worsted,"  whi  e  the  knitted 
fabric  composed  o  these  yarns  is  known  as  "  merino."  A  well-known 
suiting  fabric  made  up  of  a  cotton  warp  and  a  worsted  filling  is  known  as 


Fig.  261. — Apparatus  for  Chloring  and  Washing  Union  Goods  to  Clear  White  Cotton, 


"  cotton  worsted";  a  much-used  lining  fabric  composed  of  wool  and 
CO  ton  yarns  is  called  "  Italian  Cloth."  And  thus  the  wool-cotton  fabric 
is  to  be  met  with  under  the  guise  of  a  variety  of  names  depending  upon  the 
make-up  and  weave  of  the  goods.  The  best  c'ass  name,  perhaps,  for  all 
of  these  goods,  as  far  as  the  dyer  is  concerned,  is  union  or  half- wool  material. 
The  use  of  cotton  n  connection  w'th  wool  in  the  preparation  of  fabrics 
is  generally  c  onsidered  to  be  chiefly  for  the  purpose  of  producing  a  cheaper 
class  of  goods  while  imitating  as  far  as  possible  the  make-up  and  appear- 
ance of  all-woolen  goods.  While  this  is  true  to  a  certain  extent,  there  are 
many  instances  where  the  use  of  the  cotton  is  chiefly  for  the  purpose  of 


526  DYEING   OF   FABRICS   CONTAINING   MIXED   FIBERS 

obtaining  a  fabric  with  certain  required  properties  which  could  not  be 
obtained  with  wool  alone.  In  the  case  of  knitted  underwear,  for  example, 
if  an  all-wool  yarn  were  used,  the  resulting  fabric  would  shrink  so  much  in 
washing  as  to  be  unsatisfactory  to  the  consumer;  also  it  would  be  rather 
unpleasant  to  wear  next  to  the  skin  on  account  of  the  rather  irritating 
and  scratching  effect  of  the  wool  fiber.  By  the  use  of  the  proper  amount 
of  cotton  in  the  make-up  of  the  yarns  used  for  the  knitting  of  this  chiss  of 
garment,  a  fabric  can  be  obtained  which  does  not  have  the  bad  effect  of 
excessive  shrinking  and  is  also  soft  to  the  skin,  at  the  same  time  possessing 
more  warmth  and  porosity  than  a  fabric  made  entirely  of  cotton.  Also 
in  the  preparation  of  many  fabrics,  a  mixed  cotton-wool  yarn  is  used,  or  a 
cotton  warp  yarn,  or  a  yarn  in  some  other  form  of  weave  construction  is 
employed  in  order  to  produce  a  cloth  having  certain  desirable  qualities 
due  to  the  presence  of  the  cotton.  From  this,  however,  it  is  not  to  be  con- 
cluded that  cotton  is  always  used  in  connection  with  wool  for  these  per- 
fectly legitmiate  purposes.  There  are  many  fabrics  that  attempt  to  mas- 
querade as  all-wool  that  contain  more  or  less  cotton  cleverty  concealed 
in  their  construction  solely  for  the  purpose  of  decei\Tng  the  consmner, 
who  very  frequently  in  good  faith  purchases  the  cloth  with  the  idea  that  it 
contains  nothing  but  wool  and  the  cheaper  fiber  is  emploj^ed  for  the  pur- 
pose of  sophistication.  This,  perhaps,  is  less  true  at  the  present  time  than 
it  Avas  formerly,  owing  to  the  fact  that  cotton  has  risen  tremendously  in 
value  and  the  margin  of  difference  in  the  price  of  the  two  fibers  i.:-  noAv  much 
leos  than  it  used  to  be. 

Cotton  is  very  largely  used  in  connection  with  recovered  wool  (known 
also  as  extract  wool,  shodcty,  mungo,  etc.)  for  the  production  of  low-grade 
cheap  suitings  and  other  fabrics  wdthin  the  purchasing  power  of  the  poorer 
classes.  These  fabrics,  of  course,  do  not  possess  the  good  qualities  and 
wearing  power  of  the  all-wool  fabrics  of  which  they  are  a  cheaper  imitation. 
On  the  other  hand,  however,  it  may  be  argued  that  were  it  not  for  the  use  of 
cotton  and  the  cheaper  forms  of  recovered  wool,  the  cost  of  such  fabrics 
v.'ould  be  largely  bej'ond  the  power  of  the  poorer  classes  to  buj',  and  they 
vrould  thus  be  deprived  of  materials  which  are  very  needful  and  useful  to 
them.  This  does  not,  however,  warrant  the  description  of  such  goods  as 
all-wool  for  the  purpose  of  wantonly  deceiving  the  purchaser  into  buying 
with  the  deluded  idea  that  in  doing  so  he  is  acquiring  a  great  bargain. 
Such  goods  have  a  distinct  field  of  usefulness  of  their  own,  but  should  be 
marketed  for  what  they  are  and  not  for  AAhat  they  imitate. 

Sometimes  the  shoddy  is  more  or  less  colored  by  a  pre%dous  dj'eing, 
and  in  this  case  it  may  be  necessaiy  to  strip  the  material  where  a  light 
shade  is  to  be  dyed  on  the  union  goods.  The  stripping  is  usualh'  done  In* 
boiling  the  goods  for  one-half  hour  with  10  per  cent  of  sulphuric  acid  and 
3  per  cent  of  chrome,  though  in  the  case  of  Ught  shoddy  boiling  with  sul- 


WOOL-COTTON   FABRICS 


527 


phuric  acid  alone  will  usually  be  sufficient.  In  stripping  the  shoddy  a  pro- 
longed boiling  must  be  avoided,  as  otherwise  the  stripped  color  may  again 
feed  onto  the  wool.  Also  after  stripping  the  goods  must  be  washed  in 
water  containing  a  little  alkali,  preferably  ammonia,  in  order  to  neutralize 
all  of  the  acid,  as  otherwise  the  affinity  of  the  cotton  for  the  substantive 
dyes  will  be  lessened  and  also  there  will  be  danger  of  the  cotton  becoming 
tendered  by  the  action  of  the  acid. 

It  is  sometimes  possible  to  strip  shoddy  union  good;^  after  the  cotton 
has  been  dyed  and  in  the  same  l^ath  that  the  acid  dye  is  applied  to  the  wool. 


Fig.  262.— Cotton  under  the  Microscope.     (X140.) 

This  IS  done  by  adding  the  acid  dye  and  the  chrome  together  to  the  acid 
bath,  so  that  the  stripping  and  the  dyeing  of  the  wool  is  thus  carried  on 
simultaneously.  Of  course,  in  such  a  process  it  is  necessary  to  use  only 
such  dyes  on  the  cotton  as  will  stand  this  treatment.  It  may  be  employed, 
for  instance,  where  Columbia  Black  (or  a  similar  black  substantive  dye) 
has  been  used  for  the  cotton.  It  is  also  necessary  to  use  only  such  acid 
dyes  as  are  fast  to  the  action  of  the  chrome.* 

*  Such  acid  dyes  are  as  follows : 

Ponceau  R,  4G  Mandarine  Guinea  Green 

Victoria  Scarlet  Naphthol  Yellow  Water  Blue  RC 

Guinea  Red  4R  Azo  Acid  Yellow  Wool  Blue  5B,  2B 

Acid  Magenta  S  Curcumeine  Guinea  Violet  4B 


528 


DYEING  OF   FABRICS  CONTAINING    MIXED   FIBERS 


3.  Detection  and  Estimation  of  Cotton  and  Wool  in  Mixed  Fabrics, — 

\Mieu  the  cotton  and  wool  threads  exist  in  tlie  cloth  as  separate  and  dis- 
tinct yarns  their  detection  and  estimation  is  a  comparatively  simple 
matter.  If  the  separate  yarns  are  picked  out  from  the  cloth  and 
untwisted  and  pulled  apart  into  a  mass  of  the  individual  fibers  the  differ- 
ence between  the  appearance  and  behavior  of  the  two  will  be  easily  appre- 
ciated. The  cotton  fibei-s  give  a  mass  which  is  denser,  flatter,  and  of  a 
different  "  handle  "'  from  that  of  the  wool.  The  latter  is  spongier,  more 
curly  and  resilient. 

On  examining  the  two  masses  of  fibers  under  a  strong  magnif^ang  glass 
or  microscope,  the  si^ecific  differences  in  appearance  and  structure  will 


Fig.  263.— Wool  under  the  Microscope.  (xl40). 

become  at  once  apparent  to  the  eye.  The  cotton  fiber  has  the  appearance 
of  a  twisted,  collapsed  tube  of  a  ribbon-like  form  and  comparatively  smooth 
on  the  surface  (see  Fig.  262),  while  the  wool  fiber  is  a  rounded  rod-Hke  fila- 
ment, usually  rather  curly,  and  exhibiting  a  ver\'  characteristic  scaly  sur- 
face (see  Fig.  263).  These  scales  are  arranged  in  an  overlapping  manner, 
somewhat  like  shingles  on  a  roof,  and  usually  the  edges  protrude  shghtly 
from  the  surface  of  the  fiber  in  a  saw-tooth  arrangement.  It  is  this  latter 
feature  that  causes  the  felting  property  of  wool,  and  also  which  causes  it 
to  feel  somewhat  raspy  when  worn  in  close  contact  with  the  skin.* 

*  After  a  little  experience  in  the  examination  of  wool  and  cotton  it  becomes  an  easy 


TESTING  WOOL-COTTON   FABRICS 


529 


Other  tests,  however,  are  also  available,  based  on  the  radical  difference 
in  the  behavior  of  cotton  and  wool  with  a  solution  of  caustic  soda.  When 
boiled  with  a  weak  solution  (o  per  cent  is  sufficient)  of  this  reagent  wool 
is  very  quickly  dissolved,  whereas  cotton  is  scarcely  affected.  Conse- 
quently 'n  cases  where  the  two  fibers  are  intimately  mixed  together  so 
that  they  cannot  be  readily  separated  from  each  other  by  simple  mechan- 
ical means,  the  procedure  is  to  take  a  weighed  sample  and  boil  it  for  about 
ten  minutes  in  a  weak  solution  of  caustic  soda.  The  wool  will  be  dis- 
solved out  of  the  yarn  or  cloth  used,  leaving  the  skeleton  of  cotton.  This 
is  washed  to  free  it  from  the  alkaline  liquor,  and  is  then  dried  in  the  air  and 
reweighed.  The  weight  so  obtained  gives  the  amount  of  cotton  present, 
while  the  difference  between  this  weight  and  that  .of  the  original  sample 


!i 


Fig.  264.— Shrinking  Machine  for  Cloth.     (Philadelphia  Textile  Machinery  Co.) 


gives  the  amount  of  wool.  This  test  will  also  serve  as  a  mere  qualitative 
test  for  the  two  fibers,  the  suspected  sample  of  cloth  being  boiled  in  the 
solution  of  caustic  soda.  If  it  cUssolves  completely  only  wool  is  present, 
whereas  if  any  cotton  is  present,  it  may  readily  be  seen  in  the  residue  that 
is  left  after  boiling. 

matter  for  one  to  readily  distinguish  between  the  two  when  thej^  are  in  separate  masses, 
even  by  a  casual  examination  with  the  naked  eye  unaided  by  the  microscope;  also  the 
feel  and  general  handle  of  the  fibers  are  very  characteristic  and  allow  them  to  be  easily 
distinguished  by  anyone  who  has  had  a  little  practice  in  the  matter.  When  the  two  fibers, 
however,  are  intimately  mLxed  together  by  being  carded  and  spun  into  one  yarn,  for 
instance,  the  detection  and  estimation  of  the  relative  quantities  of  the  two  fibers  becomes 
a  somewhat  more  difficult  matter.  Under  such  circumstances  it  usually  becomes  neces- 
sary to  unravel  the  yarn  and  tease  out  the  fibers  so  as  to  separate  them  individually, 
and  then  examine  the  mass  under  the  microscope.  This  will  at  once  show  the  fibers  in 
contradistinction  to  one  another,  and  by  noting  the  amounts  of  the  two  in  a  represen- 
tative sample  a  rough  idea  of  their  relative  proportions  raay  be  obtained. 


530  DYEING   OF   FABRICS   COXTAIXIXG    MIXED   FIBERiS 

4.  Properties  of  Union  Goods. — As  cotton  and  wool  possess  very  dif- 
ferent properties  in  their  behavior  towards  dyastuffs,  mordants,  and  the 
various  chemical  agents  employed  in  dyeing,  bleaching,  and  finishing  of 
fabrics,  and  also  as  these  two  fibers  are  distinctly  different  in  their  physical 
properties  and  characteristics,  it  is  to  be  expected  that  the  processing  of 
union  goods  involves  many  differences  in  operation  from  those  where  the 
material  treated  consists  of  the  one  fiber  only.  Owing  to  this  variation  in 
the  nature  of  the  two  filiers,  the  processes  of  dyeing  union  goods  are  rather 
more  complicated  and  more  difficult  than  is  the  case  when  handling  woolen 
or  cotton  goods  alone.  A  knowledge  of  the  relative  behavior  of  the  two 
fibers  is  essential,  and  considerable  ingenuity  must  sometimes  be  employed 
in  order  to  obtain  the  results  desired.  Certain  facts  must  be  clearly  borne 
in  mind;  as  already  pointed  out  above  in  the  testing  of  wool  and  cotton, 
the  former  fiber  is  verj^  susceptible  to  the  action  of.  alkalies,  especially  in 
hot  solutions;  therefore  it  is  not  permissible  to  subject  union  goods  tc 
processes  involving  the  use  of  strongh'  alkaline  liquors,  such  as  are  fre- 
quently emploj'ed  in  connection  with  cotton.  On  the  other  hand,  cotton 
is  quite  sensitive  to  the  action  of  acids  or  solutions  of  certain  salts  of  an 
acid  nature,  especiallj'  if  such  solutions  are  allowed  to  dry  into  the  fiber. 
Under  such  conditions  the  fiber  becomes  weakened  and  rotten  and  in  time 
totally  destroyed.  Wool  is  not  sensitive  in  this  manner  to  acids,  and  many 
dyeing  operations  where  wool  alone  is  in  cjuestion,  illfake  free  use  of  acid 
liquors;  but  such  conditions  must  be  avoided  where  union  goods  are 
involved,  or  the  process  must  be  so  modified  as  to  protect  the  cotton  from 
the  action  of  the  acid. 

Wool  rather  easily  takes  up  certain  metalUc  salts  which  act  as  mordants 
for  the  fixation  of  dyestuffs,  whereas  cotton  is  ver^'  weakly  reactive  towards 
such  salts,  and  does  not  absorb  them  in  sufficient  amount  to  be  useful  as 
mordants  for  dyes.  Again,  wool  combines  with  certain  dyes  readily,  while 
cotton  is  practically'  inert  towards  the  same  dyes;  and  furthermore  certain 
dyes  require  special  methods  for  their  proper  fixation  on  cotton  which  com- 
bine directly  with  wool.  It  may  be  seen,  therefore,  that  dyeing  processes 
which  might  i)e  suitable  for  the  dyeing  of  wool  would  not  be  available  for 
the  dj'eing  of  union  goods. 

5.  Bleaching  of  Union  Goods. — Bleaching  processes  are  seldom  cm- 
plo3'ed  in  connection  with  union  goods,  as  it  is  verj^  seldom  required  that 
such  fabrics  be  marketed  in  the  white  condition.  Also  it  is  ver>^  seldom 
that  they  are  dyed  in  light  shades  or  tints  for  which  a  bleached  bottom 
would  be  necessaiy.  Dark  colors  are  more  often  used,  such  as  blues, 
browns,  and  blacks.  If  it  should  be  recjuired,  however,  to  bleach  a  fabric 
composed  of  wool  and  cotton  the  most  convenient  and  satisfactory  process 
would  be  to  employ  the  peroxide  method,  the  goods  being  steeped  for 
several  hours  in  a  1  per  cent  solution  of  hydrogen  peroxide,  prepared 


ACTION   OF   DYES  ON   UNION   GOODS  531 

either  directly  from  a  strong  hydrogen  peroxide  solution  by  proper  dilu- 
tion or  indirectly  by  the  use  of  sodium  peroxide  dissolved  in  water  con- 
taining a  sufficient  quantity  of  sulphuric  acid  to  neutralize  the  alkah. 
The  usual  method  of  bleaching  cotton  with  solutions  of  chloride  of  lime 
cannot  be  employed,  as  the  wool  would  be  discolored  and  weakened. 
Also  the  usual  method  of  bleaching  wool  by  the  action  of  fumes  of 
burning  sulphur  or  with  solutions  of  sodiimi  bisulphite  is  not  available, 
as  these  agents  do  not  satisfactorily  bleach  the  cotton  while  the  acid  devel- 
oped in  the  process  is  liable  to  seriously  injure  the  cotton  fiber. 

6.  Action  of  Dyestuffs  on  Union  Goods. — Before  proceeding  to  a  con- 
sideration of  the  specific  methods  of  dyeing  various  kinds  of  wool  and 
cotton  mixtures,  it  will  be  well  to  first  discuss  the  behavior  of  the  different 
classes  of  dyestuffs  on  this  character  of  material.  For  this  purpose  it  will 
be  sufficient  to  classify  the  different  dyes  under  the  following  groups:  (a) 
basic  dyes;  (6)  acid  dyes;  (c)  substantive  dyes;  (d)  sulphur  dyes;  (e) 
mordant  dyes;   (/)  vat  dyes;  and  (g)  vegetable  dyes. 

The  basic  dyes  have  but  little  affinity  for  the  cotton  fiber,  and  in  con- 
sequence cannot  be  dyed  on  this  fiber  directly,  but  require  the  use  of  a 
mordant,  such  as  tannic  acid  fixed  with  tartar  emetic;  these  dyes,  however, 
are  dyed  very  readily  on  wool  directly  from  neutral  baths,  and  usually 
their  affinity  for  this  fiber  is  so  strong  that  in  order  to  produce  even  colors 
it  is  necessary  to  retard  the  dyeing  by  the  use  of  a  small  amount  of  acid 
in  the  dyebath. 

The  acid  dyes  have  even  less  affinity  for  cotton  than  the  basic  dyes, 
and  only  give  stains  on  this  fiber  when  used  directly;  there  is  even  no  very 
satisfactory  method  for  mordanting  the  cotton  whereby  it  may  be  dyed 
with  acid  colors  having  a  satisfactory  fastness  to  washing,  consequently 
these  dyes  have  little  or  no  use  in  tliis  connection.  The  acid  dyes,  how- 
ever, have  a  strong  affinity  for  the  wool  fiber,  and  are  used  very  largely 
for  this  fiber,  being  dyed  directly  from  baths  containing  acid.  In  the  dye- 
ing of  union  goods,  therefore,  the  acid  dyes  are  employed  chiefly  for  shading 
the  wool  while  leaving  the  cotton  undyed.  As  it  is  not  a  very  good  thing 
to  use  hot  acid  baths  in  connection  with  cotton,  recourse  is  generally  had 
to  those  acid  dyes  which  will  be  taken  up  by  the  wool  even  from  neutral 
baths  or  from  baths  acidulated  with  such  weak  organic  acids  as  acetic  or 
formic  acids,  as  these  have  but  httle  effect  on  cotton,  and  their  use  is  not 
attended  with  any  special  danger  to  this  fiber. 

The  substantive  dyes  are  perhaps  the  most  important  class  of  colors  for 
the  dyeing  of  union  fabrics,  as  these  dyes  are  taken  up  by  lx)th  the  cotton 
and  the  wool  from  neutral  or  slightly  acid  baths.  Even  here,  however,  a 
proper  selection  of  the  dj^es  must  be  made,  as  some  of  the  substantive  dyes 
have  a  greater  affinity  for  the  cotton  than  the  wool,  some  have  about  the 
same  affinity  for  both  fibers,  while  others  have  a  stronger  attraction  for 


532 


DYEING   OF   FABRICS   CONTAINING   MIXED   FIBERS 


the  wool.  In  most  cases,  however,  the  tone  of  the  color  is  somewhat  dif- 
ferent on  the  cotton  than  it  is  on  the  wool,  even  where  the  dye  possesses 
the  same  affinity  for  both  fibers.  In  such  cases  it  is  necessary  to  tone  the 
wool  to  match  the  cotton  or  special  methods  of  dyeing  are  employed  so  as 
to  regulate  the  relative  amounts  of  the  dj'e  taken  up  by  both  fibers  respec- 
tively. This  is  generally  accomplished  by  a  proper  regulation  of  the  tem- 
perature of  the  dyebath  or  by  having  it  slightly  acid  or  alkahne.  IVIost 
of  the  substantive  colors  dye  better  on  the  wool  at  temperatures  near  the 
boil,  whereas  they  dye  better  on  the  cotton  in  lukewarm  baths.  In  weakly 
alkaline  baths  the  attraction  of  the  dye  for  the  wool  is  lessened,  while 
that  for  the  cotton  is  somewhat  increased.  By  using  a  slightly  acid  bath 
the  opposite  effect  may  be  obtained. 

The  sulphur  dyes  are  primarily  cotton  dyes,  as  they  have  to  be  applied 
from  baths  rather  strongly  alkahne  with  sodium  sulpliide  in  order  properly 


Fig.  265. — Cloth-Spreading  and  Rolling  Machine  with  Hot  Water  Box.     (Curtis  & 

INIarble.) 


to  dissolve  the  dyestuff.  As  this  alkali  exerts  a  strong  dissolving  action  on 
wool,  it  is  not  possible  to  dj^e  union  goods  in  such  a  bath,  and  in  conse- 
quence this  class  of  dyes  has  little  or  no  use  for  this  class  of  goods.  There 
are  some  special  jnethods  which  make  it  possible  to  use  these  colors  to 
some  extent,  such  as  the  use  of  anmionium  sulphide  in  place  of  sodium 
sulphide,  and  keeping  the  bath  at  a  low  temperature,  and  also  using  glucose 
in  the  bath.  But  none  of  these  methods  is  of  any  very  practical  impor- 
tance, and  possesses  httle  more  than  academic  interest.* 

*  A  large  quantity  of  union  goods,  however,  is  made  up  by  first  dyeing  the  cotton  in 
the  yarn  (either  as  skein  or  warp)  with  a  sulphur  color,  such  as  Sulphur  Black,  Brown, 
or  Blue,  then  weaving  with  the  wool  and  subsequently  dyeing  the  woven  piece  with  acid 
colors.  The  suli)hur  dyes  are  especially  suitable  to  this  style  of  dyeing,  as  they  are  fast 
to  the  boiling  acid  bath  that  is  used  for  dyeing  the  wool,  and  are  in  consequence  often 
spoken  of  as  "  cross-dj^e  "  colors,  as  this  process  of  dj'cing  is  known  to  the  dyer  as  cross- 
dyeing.  Also  sulphur  dyes  may  be  applied  to  loose  cotton  which  is  subsequently  spun 
up  with  undyed  wool  to  form  a  mix  or  blend.     The  wool  may  be  afterwards  dj'ed  to 


ACTION  OF  DYES  ON  UNION  GOODS  533 

The  mordant  dyes  require  the  use  of  a  metallic  n:iordant  for  their  proper 
fixation  of  the  fiber,  whether  of  cotton  or  of  wool.  As  cotton  cannot 
readily  be  mordanted  for  this  purpose,  these  dyes  have  but  little  applica- 
tion to  union  goods.  The  further  fact  that  the  mordanting  operations 
required  for  wool  would  apt  to  be  injurious  to  the  cotton  also  considerably 
limits  the  possibilities  of  using  the  mordant  dyes  in  this  connection.  For 
the  production  of  certain  fast  colors,  however,  and  especially  blacks  (as 
for  example  of  hosiery),  it  is  possible  to  first  dye  the  cotton  in  the  loose 
stock  with  a  sulphur  color,  and  after  the  hosiery  has  been  knitted  with  the 
wool  in  the  undyed  state,  the  piece  is  dyed  with  an  after-chromed  wool 
black  to  produce  a  uniformly  dyed  fast  black  color.  The  sulphur  dye 
in  this  case  is  not  affected  by  the  after-chroming  dyeing  process.  In  cases 
where  a  single  thread  of  all-cotton  together  with  another  single  thread  of 
all-wool  is  used  in  the  construction  of  the  garment,  it  is  possible  first  to 
dye  the  cotton  with  the  sulphur  color  in  the  yarn  form. 

The  vat  dyes,  although  including  the  fastest  dyes  known  for  cotton,  are 
not  employed  to  any  extent  in  the  dyeing  of  wool-cotton  materials,  as 
the  special  methods  required  for  the  application  of  these  colors  are  not  well 
adapted  to  union  goods. 

Of  the  class  of  vegetable  dyes,  Logwood  is  about  the  only  one  used  to  any 
extent  in  the  dyeing  of  union  fabrics.  This  dye  is  chiefly  used  in  connec- 
tion with  a  metallic  mordant  (chrome,  iron  and  bluestone)  for  the  produc- 
tion of  a  black  color.  Sometimes  Logwood  is  used  as  a  one-bath  dye  for 
union  goods,  in  which  case  the  Logwood  is  used  in  a  bath  containing  iron, 
bluestone  and  oxalic  acid  (the  latter  to  prevent  the  prec'pitation  of  the 
color-lake  in  the  bath)  and  subsequently  adding  soda  ash  to  develop  the 
color  by  neutrahzing  the  acid.  Also  Logwood  is  considerably  used  for 
what  is  known  as  "  speck  "  dyeing.  This  relates  to  the  covering  up  of 
undyed  vegetable  fibers  in  woolen  or  worsted  cloths. 

7.  Preparation  of  Union  Fabrics  for  Dyeing. — A  large  number  of  wool- 
cotton  fabrics  do  not  require  any  special  preparation  previous  to  dyeing; 
articles  like  knit-goods,  hosiery,  etc.,  for  instance,  will  generally  only 
require  a  slight  scouring  in  a  lukewarm,  dilute  soap  bath.  Woven  cloths, 
however,  and  especially  those  containing  cotton  warps,  will  have  to  be 
given  a  more  severe  scouring  in  order  to  remove  the  sizing  materials  always 
employed  on  the  warps ;  also  in  order  to  remove  completely  the  oil  and  dirt 
in  the  wool  yarns.  In  this  process  the  wool  will  shrink  somewhat,  while 
the  cotton  practically  does  not  shrink  at  all,  or  to  a  much  less  extent      On 

match  the  cotton  (this  is  almost  entirely  limited  to  the  case  of  blacks),  but  more  often 
the  wool  is  left  in  the  undyed  condition,  thus  giving  a  gray  or  "  Oxford  "  mix,  or  if  only 
a  small  proportion  of  the  dyed  cotton  is  used,  a  silver  mix  is  obtained.  Mixed  yarns  of 
this  character  are  quite  extensively  used  for  knitting  yarns  for  underwear,  sweaters, 
and  even  many  kinds  of  woven  fabrics. 


534  D'i^IXG   OF   FABRICS  CONTAINING   MIXED   FIBERS 

this  account,  the  cloth  will  cockle  up.  and  has  to  be  put,  through  a  special 
process  known  as  "  crabbing."  Crabljing  consists  really  in  treating  the 
cloth  with  boiling  water  so  as  to  soften  up  the  wool  fiber  and  make  it  plastic, 
and  then  subjecting  the  cloth  to  heavy  pressure  or  tension  while  it  is  being 
cooled  with  cold  water.  The  wool  is  thus  "  set  "  in  its  fixed  position  and 
does  not  shrink,  so  that  the  cloth  afterwards  presents  a  smooth,  even 
appearance. 

Sometmies  the  cloth  is  singed  previous  to  crabbing  for  the  purpose  of 
burning  off  the  loose  fuzzy  protruding  fibers  in  order  to  obtain  a  smoother 
and  cleaner- looking  surface.  This,  however,  depends  on  the  character  of 
the  cloth  and  the  nature  of  finish  to  be  obtained. 

\Mien  it  is  desired  to  give  the  cloth  a  high  luster  in  the  finish  a  process 
of  steaming  (or  decatizing)  is  frequently  given  after  the  crabbing.  In 
this  operation  the  cloth  is  tightly  wound  on  a  perforated  cylinder  and 
treated  with  dry  steam,  and  then  cooled.  This  gives  the  wool  a  high  luster. 
Sometmies  the  decatizing  is  not  done  until  after  the  dj^eing,  in  which  case 
the  dyes  used  must  be  fast  to  this  process.  In  decatizing  it  is  important 
that  the  steam  used  is  dry  (does  not  contain  any  condensed  water,  which 
would  cause  spotting  of  the  goods).  Usually  steam  of  1  to  2  atmospheres 
pressure  is  used.  Also  the  cloth  as  rolled  on  the  cylinder  should  be  well 
enveloped  with  a  cloth  cover  in  order  to  prevent  the  outside  layers  from 
cooling  off  too  rapidly.  The  treatment  with  the  steam  usually  lasts  only 
from  five  to  eight  minutes,  after  which  the  cloth  is  unrolled  on  to  another 
similar  cyhnder  and  then  steamed  again  so  as  to  avoid  possible  uneven 
action,  as  the  end  which  was  first  inside  now  becomes  the  outside  end. 
After  steaming  the  c^'linder  of  cloth  should  be  placed  in  a  horizontal 
frame  and  turned  slowlj'  for  about  half  an  hour  in  order  to  permit  of  an 
even  cooling. 

After  decatizing  the  goods  are  read}'  for  dyeing,  and  for  such  goods  the 
dyeing  should  be  done  in  machines  permitting  of  running  the  cloth  in  the 
open  width  to  prevent  the  development  of  crease  marks.  Goods  that  are 
not  decatized  may  be  dyed  in  the  rope  form  very  often,  though  this  will 
naturally  depend  upon  the  particular  character  of  the  goods  being 
handled. 

8.  The  Dyeing  of  Union  Fabrics. — From  the  pre\aous  consideration  of 
the  different  behavior  of  wool  and  cotton  towards  the  various  classes  of 
dyestuffs  it  may  be  readily  prcsimied  that  there  is  little  difficult}'-  to  be 
experienced  in  dyeing  one  fiber  while  leaving  the  other  practically  undyed. 
If  an  acid  dye,  for  example,  is  used,  and  a  strongly  acid  boiling  bath  is 
employed,  the  wool  will  be  dyed  while  the  cotton  will  be  left  practically 
undyed.  On  the  other  hand,  the  cotton  alone  may  be  dyed  by  using  a 
fiber  mordanted  with  tannin  and  tartar  emetic  and  dyeing  with  a  basic 
color  in  a  cold  bath;    or  certain  substantive  dyes  may  be  used  (such  as 


DYEING   UNION   FABRICS 


535 


Heliotrope,  Congo  Riibine,  Diamine  Pure  Blue,  etc.)  in  a  cool  bath,  and 
the  wool  will  be  left  practically  white. 

In  practice,  however,  it  is  far  more  often  required  that  both  fibers 
should  be  dyed  as  near  as  possible  the  same  shade  in  order  to  furnish  a 
uniform  piece  of  goods.  Usually  the  cotton  should  be  dyed  a  little  bit 
darker  than  the  wool,  as  this  will  cover  it  up  better  and  its  presence  will 
not  be  so  noticeable.  It  is  frequently  necessary  to  dye  each  fiber  irre- 
spective of  the  other;  for  instance  the  wool  may  first  be  dyed  in  an  acid 
bath,  leaving  the  cotton  undyed;  then  the  cloth  is  mordanted  with  tannic 
acid  and  fixed  with  tartar  emetic,  washed  and  dyed  in  a  cold  bath  with  a 


Fig.  266.— Four-bowl  Water  Mangle.     (Mather  &  Piatt.) 


basic  dye.  During  the  latter  operation  the  color  of  the  cotton  must  be 
sampled  from  time  to  time  to  see  if  it  has  acquired  the  correct  tone  and  the 
proper  depth  of  shade.  It  is  necessary  to  use  a  cold  bath,  since  the  basic 
dyes  will  dye  on  the  wool  in  a  warm  bath.  Such  a  process,  however,  re- 
quires the  use  of  four  separate  baths,  which  makes  it  both  complicated 
and  costly.  On  this  account  it  is  seldom  employed  except  for  certain 
special  kinds  of  material. 

A  simpler  process,  requiring  only  the  use  of  two  baths,  is  first  to  dj^e 
the  wool  as  before  with  an  acid  dyestuff  and  then  to  dye  the  cotton  in  a 
second  bath  with  a  substantive  dyestuff,  using,  if  necessary,  a  slightly 
alkaline  bath  at  a  moderately  low  temperature  in  order  to  prevent  the 


536  DYEING   OF   FABRICS   CONTAIXIXG    MIXED   FIBERS 

wool  from  becoming  dyed.  Also,  of  course,  care  must  be  exercised  in  the 
proper  selection  of  the  dyestufTs  to  be  used.  In  using  this  process  the 
order  of  dyeing  the  two  fibers  may  sometimes  be  reversed ;  that  is  to  say, 
the  cotton  may  first  be  dj'ed  in  a  cold  or  lukewarm  bath  with  a  sub- 
stantive dye,  and  then  the  wool  may  be  dyed  in  a  ])oiHng  acid  bath  with 
an  acid  coloring  matter.  It  is  necessarj^  of  course,  to  use  only  such 
substantive  dyes  in  this  process  as  will  not  be  affected  l)y  the  acid  bath. 
This  method  of  procedure  is  used  quite  frequently  for  the  dj'eing  of  suit- 
ings and  dress-goods  having  a  cotton  warp  and  a  wool  filling;  the  cotton 
warp  being  dyed  previous  to  weaving,  and  the  wool  being  subsequently 
dyed  in  the  woven  piece.  The  sulphiu-  dyes  are  especially  adapted  to  this 
method,  as  they  will  stand  the  mooI  cross-dyeing;  there  are  also  certain 
of  the  sul)stantive  dyes  which  will  stand  a  cross-dyeing  operation.* 

Another  two-bath  process  to  be  noted  is  that  which  has  to  do  chiefly 
with  the  speck  dyeing  of  black  pieces;  in  order  to  cover  up  the  cotton  (or 
other  vegetable  fibers)  which  may  be  on  the  surface  of  the  goods  the  pieces 
may  be  treated  with  sumac  and  copperas,  which  will  give  an  iron  black. 
A  better  method,  perhaps,  is  to  use  certain  substantive  black  dyes  (such 
as  Direct  Black  VT,  Pluto  Black  F  and  Diamine  Milling  Black),  which 
will  dye  well  on  the  cotton  in  a  cold  bath. 

There  are  also  single  or  one-bath  methods  for  the  dyeing  of  union  goods. 
These  chiefly  depend  on  the  use  of  substantive  dyes  so  selected  as  to  dye 
both  fibers  as  nearly  alike  as  possible.  By  properly  varying  the  tempera- 
ture and  alkalinity  of  the  bath  it  is  often  possible  to  adjust  the  absorption 
of  the  color  on  the  two  fibers  as  to  obtain  the  results  desired.  The  cloth  is 
usuall}^  dyed  for  ten  to  fifteen  minutes  in  a  boiling  bath  so  that  the  wool 
will  take  up  most  of  the  color;  then  the  steam  is  shut  off  and  the  bath  is 
allowed  to  cool  down,  when  more  dye  solution  is  added  and  the  color  is 
thus  allowed  to  feed  on  to  the  cotton .  By  proper  adjustment  of  the  con- 
ditions it  is  often  possible  to  ol^tain  very  satisfactory  uniformity  of  color. 
Unfortunately,  however,  it  is  seldom  the  case  that  one  dye  will  give  exactly 
the  same  tone  of  color  on  both  fillers,  so  that  it  is  usually  necessary  to  shade 
either  the  cotton  or  the  wool  with  other  dj'es.  When  the  cotton  is  to  be 
shaded,  this  is  usually  done  by  adding  the  required  dye  in  the  cooled  bath. 
When  the  wool  is  to  be  shaded  a  suitable  acid  dye  is  added,  or  certain 
special  dyes  may  be  used  (such  as  the  Sulphon  dyes)  which  only  dye  the 

*  For  the  better  classes  of  half-woolen  fabrics  the  cotton  is  usually  dyed  in  the  form 
of  warps  previous  to  weaving;  this  is  particularly  true  of  blacks,  browns,  and  other  heavy 
colors.  By  this  means  there  is  less  injury  and  alteration  of  the  wool  and  the  goods  can 
be  given  a  softer  and  better  handle.  Furthermore,  clearer  and  brighter  colors  can  be 
obtained.  There  is  also  a  greater  diversity  possible  in  the  selection  of  the  dyestuffs  to 
be  employed.  In  the  case  of  the  lower  grades  of  half- wool  fabrics,  especially  those  con- 
taining shoddy  and  recovered  wool  with  cotton  warp,  it  is  more  customary  to  dve  both 
fibers  in  the  piece  after  weaving.     This  is  especially  true  where  light  colors  are  used. 


DYEING    PROCESSES  537 

wool  in  a  hot  bath.*  Rhodamine  and  other  similar  acid  dyes  that  will 
take  up  on  the  wool  from  a  neutral  bath  are  very  useful  for  shading  pur- 
poses (such  as  Fast  Red  A,  Croceine  Scarlet,  etc.).  This  shading  may  be 
carried  out  in  the  same  bath,  but  requires  considerable  ski.l  and  experience 
in  order  to  obtain  the  desired  results.  This  is  especially  the  case  where 
it  is  necessary  to  match  a  given  shade  or  particular  tone  of  color. 

Since  the  introduction  of  the  substantive  cotton  dyes  the  use  of  the  one- 
bath  process  for  the  dyeing  of  union  goods  has  been  greatly  extended  and 
improved.  It  has  gradually  come  to  be  the  one  most  favored  by  dyers, 
as  it  is  now  possil^le  to  obtain  almost  any  desired  effect  with  a  minimum 
handling  of  the  goods  and  a  great  simplicity  of  process,  so  that  there  is 
little  difficulty  experienced  in  matching  of  shades  to  sample  and  in  bringing 
up  the  color  of  both  fibers  to  the  same  tone  and  depth.  As  a  consequence, 
the  older  and  more  complicated  processess  of  dyeing  union  goods  have  been 
more  and  more  abandoned. 

9.  Dyeing  Processes  for  Union  Goods. — The  details  for  the  proc- 
esses for  wool-cotton  goods  may  now  be  considered  with  special 
reference  to  the  different  classes  of  dyes  to  be  employed. 

(a)  Tivo-hath  Process. — The  wool  portion  is  first  dyed  with  the  suitable 
acid  dyes  in  the  customary  manner  using  a  dyebath  to  which  is  added  4 
per  cent  of  sulphuric  acid  and  10  per  cent  of  glaubersalt.  The  necessary 
dye  or  mixture  of  dyes  is  first  dissolved  in  hot  water  and  then  added  to  the 
bath.  The  goods  are  dyed  for  about  an  hour  at  a  temperature  of  about 
200°  F,  Instead  of  using  acid  and  glaubersalt,  10  per  cent  of  sodium 
bisulphate  may  be  employed.  The  material  is  then  washed  in  order  to 
remove  the  excess  of  acid  and  dye  solution  and  the  cotton  is  mordanted 
by  passing  into  a  bath  containing  2  to  10  per  cent  of  tannin  (depending 
on  the  depth  of  color  to  be  dyed).  The  goods  are  entered  at  a  tempera- 
ture of  about  200°  F.,  the  heat  shut  off  and  the  cloth  run  in  the  cooling 
bath  for  one  hour.  In  order  to  fix  the  tannin  in  an  insoluble  form  the 
cloth  is  then  run  through  a  cold  bath  containing  2  per  cent  of  tartar  emetic. 
This  is  an  antimony  salt  and  forms  an  insoluble  antimony  tannate  with 
the  tannin.  Rinse  and  finally  dye  in  a  bath  containing  a  suitable  basic 
dyestuff  together  with  2  per  cent  of  acetic  acid.  The  dyeing  should  be 
done  cold,  or  at  least  not  over  lukewarm,  in  order  to  prevent  the  color 
being  taken  up  by  the  wool.     The  dyeing  in  this  bath  should  be  so  manipu- 

*  In  matching  of  union  goods  in  dyeing  to  a  sample  it  must  be  remembered  that  by 
prolonged  boiling  the  substantive  dyes  tend  to  feed  off  from  the  cotton  onto  the  wool, 
and  that  after  having  matched  the  sample  with  respect  to  the  cotton,  and  then  trying  to 
boil  on  more  color  to  the  wool,  it  is  possible  to  let  down  the  color  on  the  cotton  so  that 
the  latter  no  longer  shows  a  match.  Therefore  superfluous  boiling  of  the  bath  should  be 
avoided.  It  should  also  be  noted  that  either  stripped  or  unstripped  shoddy  takes  up 
the  dye  more  readily  than  pure  wool,  therefore  in  dyeing  such  material  only  those  sub- 
stantive dyes  should  be  selected  which  stain  the  wool  least. 


538 


DYEING   OF   FABRICS   CONTAINING   MIXED   FIBERS 


lated  by  additions  of  dj'estuff  solution  that  the  cotton  is  dyed  a  slightly 
heavier  shade  than  the  wool. 

(6)  Txco-haih  Process. — The  wool  is  first  dyed  with  an  acid  dye  as  above 
described  and  then  rinsed  and  dyed  in  a  second  bath  with  a  suitable  sub- 
stantive cotton  dye  in  a  cold  or  lukewarm  bath  with  the  addition  of  10 
to  20  per  cent  of  glaubersalt. 

(c)  Two-bath  Process. — The  wool  is  first  dyed  with  an  acid  dye  as 
above  described,  rinsed,  and  the  cotton  is  mordanted  with  tannin  or  sumac 
and  then  fixed  with  copperas  or  the  so-called  nitrate  of  iron  (which  is 
really  a  basic  sulphate  of  iron).  The  tannin  and  the  iron  salt  give  a  bluish 
black  or  dark  slate  color,  so  tliis  process  is  used  only  for  dark  blues  or  blacks. 


Fig.  267. — Palmer  Machine  for  Finishing  Cashmeres,  etc. 


After  fixing  with  the  iron  salt  it  is  recommended  to  rinse  the  goods  in  a  bath 
containing  some  lime  water.* 

(d)  Two-bath  Process. — The  wool  is  first  dj^ed  with  an  acid  dye  as 
before;  the  goods  are  rinsed  and  the  cotton  is  dj-ed  in  a  cold  bath  with 
suitable  substantive  black  dyestuffs.  This  method  is  used  chiefly  for 
"  speck  "  dyeing  of  black  colors.! 

*  For  the  dyeing  of  blacks  the  following  method  is  frequenth'  employed:  The  cloth 
is  first  given  a  treatment  with  a  tannin  bath  to  mordant  the  cotton,  followed  by  a  fixing 
bath  with  copperas  and  bluestone;  the  wool  is  then  mordanted  with  chrome  and  the 
dyeing  is  done  with  Logwood  (properly  toned  with  Fustic). 

t  This  method  is  frequently  employed  where  the  wool  in  the  union  material  will  not 
stand  a  long  boiling  in  a  neutral  bath,  and  it  is  also  preferred  when  it  is  desired  to  give 
the  wool  a  firmer  feel.  The  process  is  also  called  "  burl  "  dyeing,  and  is  intended  chiefly 
for  the  purpose  of  covering  up  the  cotton  so  that  it  will  not  be  easily  apparent.     After 


DYEING   PROCESSES  539 

(e)  Two-hath  Process. — The  cotton  is  first  dyed  in  a  cold  bath  with 
suitable  substantive  dyes  which  are  fast  to  cross-dyeing.  The  dyeing  is 
usually  done  on  the  jigger  in  a  short  bath.  The  goods  are  rinsed  and  then 
the  wool  is  dyed  with  Sulphon  dyes  or  other  suitable  acid  dyes  that  may  be 
used  in  a  bath  with  ammonium  acetate  instead  of  sulphuric  acid.* 

(/)  One-bath  Process. — The  material  is  dyed  in  a  bath  with  suitable 
substantive  dyes  with  the  addition  of  30  to  60  per  cent  of  glaubersalt.  f 

The  bath  is  heated  to  a  boiling  temperature  and  the  goods  are  run  for 
about  half  an  hour,  and  then  a  sample  is  taken  for  matching;  if  the  wool  is 
too  light,  J  or  if  it  does  not  have  the  proper  tone  of  color,  it  is  matched  up 
by  adding  the  necessary  color  and  continuing  the  boiling  for  a  short  time. 
If,  on  the  other  hand,  the  cotton  is  too  light,  the  steam  is  shut  off  and  the 
goods  are  run  in  the  cooling  bath  and  if  necessary  an  addition  of  the  proper 
cotton  dyestuff  is  made.  After  dyeing  the  goods  are  rinsed  and  dried. 
The  dyebath  is  preserved  for  subsequent  lots  with  the  necessary  additions 
of  dyes  and  a  small  quantity  more  of  glaubersalt. 

the  acid  dye  has  been  appHed  to  the  wool,  the  goods  should  be  rinsed  in  a  bath  contain- 
ing a  little  ammonia  or  soda,  and  then  the  cotton  is  dyed  with  such  cotton  colors  as  may 
be  applied  in  a  fresh  cold  bath.  An  addition  of  about  10  lbs.  of  glaubersalt  per  100 
gallons  of  liquor  is  made,  both  the  dye  and  the  salt  being  first  dissolved  in  boiling  water 
and  then  added  to  the  cold  bath. 

*  This  method  is  often  employed  for  the  dyeing  of  blacks  on  shoddy  material  which 
does  not  require  the  cotton  warp  to  be  dyed  exactly  the  same  shade  as  the  woo  as  long  as 
it  is  covered  in  a  manner  that  conceals  its  presence.  The  cotton  is  first  dyed  with  Colum- 
bia Black  (or  other  suitable  substantive  black  dye  which  is  fast  to  treatment  with  dilute 
acid  at  a  boiling  temperature) .  The  bath  is  made  up  as  concentrated  as  possible  with 
6  per  cent  of  Columbia  Black,  20  per  cent  of  glaubersalt  and  3  per  cent  of  soda  ash,  and 
the  goods  are  dyed  at  140  to  160°  F.  until  the  cotton  is  sufficiently  covered.  Then 
rinse  and  dye  the  wool  in  a  fresh  bath  with  acid  dyes  with  the  addition  of  10  per  cent 
of  glaubersalt  and  5  to  10  per  cent  of  sulphuric  acid.  In  this  second  bath  it  is  necessary 
to  enter  the  goods  at  a  low  temperature  and  gradually  raise  to  the  boil  in  order  to  first 
completely  fix  the  black  on  the  cotton,  as  otherwise  the  wool  may  become  stained. 

A  modification  of  this  process  in  order  to  save  time  on  goods  that  are  to  be  fuUed  is 
to  dye  the  cotton  with  the  black  during  the  fulling  operation.  This  is  especially  suitable 
for  cheap  shoddy  materials  where  the  cost  of  operation  must  be  reduced  to  a  minimum. 
There  is  added  to  the  fulling  liquor  (according  to  the  amount  of  cotton  present)  3  to 
5  per  cent  of  Columbia  Black  FBW.  Shortly  before  the  fulling  is  finished  a  little 
glaubersalt  may  be  added.  The  goods  are  then  rinsed  and  dyed  with  acid  dyes,  taking 
care  that  the  bath  is  sufficiently  acid  before  entering  the  goods  in  order  to  avoid  the 
staining  of  the  wool  by  the  cotton  dye. 

t  While  the  amount  of  glau'  ersalt  (or  common  salt)  used  depends  on  circumstances, 
an  excess  should  be  avoided,  as  this  may  produce  a  precipitation  of  the  dyestuff  in  the 
bath  which  may  lead  to  cloudy  and  bronzy  dyeings.  The  amount  of  salt  in  the  liquor 
should  be  such  that  it  does  not  show  a  hydrometer  reading  of  over  3°  Tw. 

X  Care  should  be  taken  not  to  get  the  wool  too  dark,  for  if  this  occurs  the  cloth  had 
best  be  set  aside  to  dye  a  darker  shade,  and  if  this  is  not  possible  the  goods  wil'  have  to 
be  stripped  down  in  a  fresh  bath. 


540  DYEING   OF  FABRICS   CONTAINING   MIXED   FIBERS 

Not  only  is  the  regulation  of  the  temperature  of  the  bath  necessary 
to  secure  the  desired  results,  but  the  concentration  of  the  dyebath  also 
plays  an  important  role.  The  higher  the  concentration  of  the  bath  the 
more  readily  will  the  desired  shade  be  obtained  on  the  cotton.  It  is  best 
to  employ  a  rather  short  bath  (1 :  25)  and  to  use  5  to  20  lbs.  of  glaubersalt 
per  100  gallons  of  liquor  (depending  on  the  depth  of  color  required). 
For  the  dyeing  of  blacks  and  hea\'y  browns  a  larger  addition  of  glaubersalt 
may  be  required.  It  is  also  best  to  heat  the  bath  with  a  closed  steam  coil 
rather  than  with  direct  steam  so  as  to  avoid  unduly  diluting  the  bath.  The 
addition  of  a  small  quantity  (about  f  per  cent)  of  soda  will  cause  the  dye 
to  be  taken  up  less  on  the  wool,  whereas  the  addition  of  a  little  acetic  acid 
will  make  the  dye  feed  onto  the  wool  better.  Furthermore,  as  the  quantity 
of  the  dye  taken  up  by  the  cotton  in  the  material  depends  to  a  large  extent 
on  the  concentration  of  the  dj^ebath,  it  will  be  necessary  to  use  the  same 
amount  of  dyestuff  irrespective  of  the  proportion  of  the  cotton.  As  the 
many  union  materials  contain  cotton  and  wool  mixed  in  all  possible  pro- 
portions it  will  be  found  that  those  containing  a  small  percentage  of  cotton 
will  require  relatively  more  dyestuff  than  those  containing  a  high  per- 
centage of  this  fiber.  This  will  be  understood  in  considering  the  fact  that 
whereas  the  most  advantageous  proportion  of  liquor  to  cotton  is  about 
1:25,  in  goods  containing  equal  parts  of  wool  and  cotton,  this  quantity 
of  liquor  would  amount  to  only  a  proportion  of  1 :  50  on  the  weight  of  the 
cotton,  consequently  to  make  up  for  this  relative  dilution  of  the  bath  a 
larger  proportion  of  dyestuff  will  be  required. 

(g)  One-bath  Process. — The  dyebath  is  prepared  wdth  boiling  water  and 
the  solution  of  the  dyestuff  and  sufficient  cold  water  is  added  to  bring  the 
temperature  down  to  about  140°  F.,  then  enter  the  goods,  run  for  half  an 
hour,  bring  to  the  boil,  and  take  a  sample  for  matching.  If  the  cotton  is 
dark  enough  but  the  wool  is  too  light,  add  a  neutral  dyeing  acid  color  to 
match  up  on  the  wool. 

(h)  One-bath  Process. — The  dyeing  is  done  in  a  warm  bath,  using  the 
required  substantive  dyes  for  the  cotton  and  the  proper  neutral  dyeing 
acid  colors  for  the  wool  with  20  to  30  per  cent  of  glaubersalt  and  dyeing  at 
the  boil  until  the  shade  is  matched.* 

The  selection  of  which  process  to  emploj^  must  be  left  to  the  judgment 
of  the  dyer,  depending  on  the  nature  and  character  of  the  goods  being  dyed. 
Considerable  ingenuity  must  often  be  exercised  in  order  to  obtain  the  proper 
results  without  disastrous  effects  on  the  fabric.  It  is  usually  best  to  make  a 
test  dyeing  first  in  order  to  determine  which  process  and  what  dyestuffs 
are  the  best  to  employ  in  any  given  case. 

(i)  Process  for  Two-color  Dyeings. — Certain  kinds  of  half -wool  material 

*  This  process  is  also  adapted  to  burl  dyeing  for  the  purpose  of  covering  the  cotton 
especially  when  only  a  small  amount  of  this  fiber  is  present . 


DYEING   TWO-COLOR  EFFECTS 


541 


are  sometimes  dyed  so  as  to  produce  a  two-color  effect,  with  one  color  on 
the  cotton  and  another  color  on  the  wool.  When  it  is  necessary  to  match 
these  colors  to  a  given  sample  the  problem  is  at  times  quite  difficult,  but 
by  the  use  of  suitable  dyeings  with  the  substantive  cotton  colors  and  the 
neutrai  dyeing  acid  colors  for  wool  a  great  variety  of  effects  are  possible. 
10.  Two-color  Effects. — For  the  production  of  two-color  effects  it  is 
best  to  employ  the  two-bath  method,  dyeing  the  wool  first  in  an  acid  bath 
and  then  dyeing  the  cotton  in  a  fresh  cold  bath  with  suitable  substantive 
colors.  It  is  advisable  to  rinse  the  goods  after  dyeing  the  wool,  using  a 
bath  containing  a  small  amount  of  ammonia  or  soda  ash.     One-bath 


Fig.  268.— Silk  Finishing  Machine. 


methods  may  also  be  employed,  using  acid  dyes  which  may  be  applied  in  a 
neutral  bath  together  with  substantive  dyes;  but  this  method  gives  less 
brilliant  colors,  though  it  is  possible  to  obtain  fairly  good  effects  if  the 
neutral  dyeing  acid  color  is  first  added  alone  to  the  boiling  bath,  and  sub- 
sequently the  cotton  colors  after  the  bath  has  cooled  down. 

11.  Classification  of  Dyes  for  Union  Goods. — With  respect  to  their 
behavior  in  the  dyeing  of  union  goods,  the  substantive  dyes  may  be  classi- 
fied as  follows,  according  to  their  action  in  a  boiling  neutral  salt  bath : 


(a)  Dyes  wliich  color  the  cotton  darker  than  the  wool. 
(6)  Dyes  which  color  both  fibers  approximately  ahke. 
(c)  Dyes  which  color  the  wool  darker  than  the  cotton, 
auxiliary  dyes  for  purposes  of  toning  there  may  be  mentioned : 


And  for 


542 


DYEING  OF  FABRICS   CONTAINING   MIXED   FIBERS 


(d)  Acid  dyes  which  color  the  wool  satisfactorily  in  a  boiling  neutral 
bath,  leaving  the  cotton  white  or  practically  undyed.  * 

The  following  is  a  list  of  the  principal  dyes  in  these  different  classes: 


Dyeing  the  Cotton  Darker  than  the  "Wool 
Diamine  Jot  Black  CR 
Diamine  New  Blue  G,  R 
Diamine  Nitrazol  Brown  G 
Diamine  Orange  G 
Diamine  Pure  Blue  A 
Diamine  Sky  Blue  FF 
Diamine  Violet  N,  BB 
Dianil  Black  PR,  PG,  HW 
Dianil  Blue  G,  B,  II 
Dianil  Browns 
Dianil  Dark  Blue  R,  3R 
Dianil  Fast  Brown  B 
Dianil  New  Black  LB 
Dianil  Orange  G 
Diazo  Black  BHN 
Direct  Blue  2B 
Direct  Brown  V 
Direct  Rose  T 
Direct  Violet  N 
Direct  Yellow  R,  T 
Heliotrope  BB 
Mikado  Golden  Yellow  8G 
Mikado  Orange  G 
Mikado  Orange  GO,  4R0 
Mikado  Yellow 
Oxy  Diamine  Black  KW,  A, 
Oxy  Diamine  Blue  G,  B,  R 
Oxy  Diamine  Brown  RN 
Oxy  Diamine  Violet  B,  R,  G 
Para  Diamine  Black  B 
Pluto  Black  CR,  F 
Solamine  Blue  FF 
Union  Blue  Black 
Zambesi  Black  B  and  R 
Zambesi  Brown  G  and  2G 


(A) 
Acetylene  Blue  3B,  6B 
Benzo  Azurine  G 
Benzo  Brown  D3G 
Benzo  Fast  Blue 
Benzo  Fast  Scarlets 
Benzo  Fast  Violet  R 
Benzo  Sky  Blue 
B?nzo  Violet  R 
Brilliant  Azurine  B 
Chloramine  Orange 
Chloramine  Yellow 
Chlorantine  Orange 
Chlorantine  Yellow 
Columbia  Blue  G  and  R 
Columbia  Brown  R 
Columbia  Fast  Blue  2G 
Columbia  Green 
Columbia  Yellow 
Congo  Fast  Blue  HW 
Cupranil  Brown  B,  R 
Curcumine  S 
Diamine  Bengal  Blue  R 
Diamine  Black  BH 
Diamine  Blue  BB,  BG 
Diamine  Bordeaux  B 

Diamine  Brilliant  Blue  R  Oxv  Diamine  Black  KW,  A,  D 

Diamine  Brown  ATC 
Diamine  Catechine  B 
Diamine  Dark  Blue  B 
Diamine  Deep  Blue  B,  R 
Diamine  Fast  Black  F 
Diamine  Fast  Blue  FFB,  G,  BN 
Diamine  Fast  Brown  G,  R 
Diamine  Fast  Scarlet  GG,  4BN,  6BS 
Diamine  Fast  Yellow  A 
Diamine  Heliotrope  B.  G 

*  All  of  the  substantive  cotton  dyes  when  dyed  in  a  bath  at  temperatures  below  the 
boiling  point  have  a  tendency  to  dye  the  cotton  more  than  the  wool.  It  appears  that 
by  reduci  ,g  the  temperature  their  affinity  for  the  wool  decreases  to  such  an  extent  that 
even  those  dyes  which  in  a  boiling  bath  dye  the  wool  more  than  the  cotton,  in  a  cold 
bath  will  leave  the  wool  almost  undyed  and  dye  almost  exclusively  the  cotton. 

Sometimes,  after  boiling  the  dyebath  the  cotton  will  not  show  the  required  depth  of 
shade,  in  which  case  the  steam  must  be  turned  off  and  the  goods  run  in  the  cooling  bath 
for  some  time,  or  suitable  dyes  may  be  added  for  purposes  of  shading.  In  this  connec- 
tion those  substantive  dyes  mentioned  in  the  list  (/i)  are  especially  adapted,  as  they  dye 
the  cotton  well  in  a  cold  bath. 


CLASSIFICATION   OF  DYES 


543 


(B)  Dyeing  Both  Fibers  Alike 


Benzo  Azurine  5G 

Benzo  Blue  RW 

Benzo  Bordeaux 

Benzo  Brown  5R 

Ben^o  Chrom    Browns 

Benzo  Cyanine  C,  R 

Benzo  Dark  Green 

Benzo  Fast  Orange 

Benzo  Fast  Red 

Benzo  Fast  Yellow 

Benzo  Green 

Benzo  Orange  R 

Benzopurp   rine  4B 

Benzo  Red 

Benzo  Rhoduline  Red 

Brilliant  Benzo  Blue 

Brilliant  Congo  R 

Brilliant  Geranine  G 

Brilliant  Orange  G 

Brilliant  Purpurine  lOB,  R 

Carbide  Black  S,  E 

Chicago  Blue  6B,  4B.  B 

Chromanil  Black  2BF 

Chromanil  Brown  2G,  R 

Clirysamine  G 

Chrysophenine  G 

Columbia  Black,  FB,  F2B,  FBW 

Columbia  Black  Blue  G 

Columbia  Violet  R 

Congo  Brown  G  and  R 

Congo  Corinth  G  and  B 

Congo  Orange  G,  R 

Congo  Red 

Congo  Rubine 

Congo  Sky  Blue 

Cotton  Brown  RN 

Cotton  Red  A 

Cotton  Yellow  R 

Cupranil  Brown  G 

Delta  Purpurine  5B 

Diamine  Azo  Blue  6B 

Diamine  Bengal  Blue 

Diamine  Black  HW 

Diamine  Blue  RW 

Diamine  Bordeaux  VRO 

Diamine  Brilliant  Bordeaux  R 

Diamine  Bro^vn  3G,  R,  M,  S 

Diamine  Catechine  G 

Diamine  Dark  Green  N 

Diamine  Fast  Red  F 


Diamine  Fast  Yellow  2F,  B   M 

Diamine  Green  G,  B,  CL 

Diamine  Green  J 

Diamine  Orange  B 

Diamine  Purpurine  B,  V 

Diamine  Red  B 

Diamine  Red  3B,  5B,  lOB,  D 

Diamine  Rose  GD,  BG 

Diamine  Steel  Blue  L 

Diamine  Violet  J 

Diamineral  Brown  G 

Diaminogene  B 

Dianil  Black  N,  E 

Dianil  Blue  BX 

Dianil  Brown  3G0,  3R 

Dianil  Claret  Red  G,  B 

Dianil  Copper  Brown  B 

Dianil  Indigo  O 

Dianil  Orange  N 

Dianil  Red  R,  4B 

Dianil  Yellow  3G,  R 

Diazo  Black 

Diazo  Blue  Black 

Direct  Black  CR 

Direct  Blue  B 

Direct  Blue  Black 

Direct  Brown  M 

Direct  Deep  Black  EW 

Direct  Fast  Brown 

Direct  Gray  B,  R 

Direct  Gray  J 

Direct  Green  B,  J 

Direct  Indigo  Blue 

Direct  Orange  GR 

Direct  Sky  Blue 

Erie  Black 

Half-wool  Black  K,  S 

Half-wool  Blue  WG 

Half-wool  Brown  M 

Orange  TA 

Oxamine  Blue  3R 

Oxamine  Claret  M,  B 

Oxamine  Copper  Blue  2R 

Oxamine  Dark  Blue  BG,  R 

Oxamine  Fast  Red  F 

Oxamine  Red,  3B 

Oxamine  Violet 

Oxy  Diamine  Black  JE,  JW 

Oxy  Diamine  Brown  G,  3GN 

Oxy  Diamine  Orange  G,  R 


544 


DYEING   OF   FABRICS   CONTAINING   MIXED   FIBERS 


Oxy  Diamine  Red  8 
Oxy  Diamine  Yellow  2G,  TZ 
Pluto  Black  BS,  3B,  TG 
Pluto  Brown  NB 
Pluto  Oranf^e  G 
Pyramine  Orange  3G 
Thiazol  Yellow 
Thioflavine  S 
Tolamine  Violet 
Toluylene  Orange  G 


Union  Black  8,  P,  BG,  2B 
Union  Blue  BJ,  RJ,  2B 
Union  Brown  TD 
Union  Dark  Brown  A 
Union  Fast  Black  J 
Union  Jet  Black  B 
Union  Navy  Blue  J 
Zambesi  Black  D 
Zambesi  Black  F 


Acetylene  Blue  3R 
Acid  Congo  R 
Benzo  Fast  Black 
Brilliant  Congo  R 
Brilliant  Dianil  Red  R 
Brilliant  Geranine  3B 
Chicago  Blue  RW 
Chlorantine  Red  4B,  8B 
Chlorantine  Rose 
Columbia  Orange  R 
Congo  Blue  BX 
Congo  Orange  R,  G 
Congo  Rubine 
Cotton  Red,  4B,  lOB 
Cotton  Yellow  CH 
Cresotine  Yellow  G 
Diamine  Bordeaux  S 
Diamine  Brown  B 
Diamine  Gold 
Diamine  Jet  Black  00 
Diamine  Orange  F 
Diamine  Rose  BD 


(C)  Dyeing  Wool  Darker  than  Cotton 

Diamine  Scarlet  B,  3B 
Diamine  Violet  Red 
Diamine  Yellow  CP 
Diaminogene  extra 
Dianil  Black  T 
Dianil  Green  G 
Dianil  Scarlet  G,  2R 
Dianil  Yellow  G 
Direct  Blue  R,  W 
Direct  Blue  Black  2B 
Direct  Brown  R 
Direct  Rose  GN,  BN 
Direct  Safranine  G,  B 
Direct  Violet,  C,  CB 
Direct  Yellow  CR 
Erica 

Geranine  G,  2B 
Nyanza  Black  B 
Pluto  Brown  G,  R 
Toluylene  Orange  R 
Wool  Brown  R  and  G 


(D)  Acid  Dyes  Leaving  Cotton  White 


Acid  Alizarine  Blue  2B 

Acid  Alizarine  Green  G 

Acid  Alizarine  Grenade  R 

Acid  Black  5B 

Acid  Black  HA,  NN 

Acid  Brown  G,  B,  V 

Acid  Green  3B 

Acid  Magenta 

Acid  Rhodamine  R 

Acid  Violet  HW,  4RS,  3BN,  7B 

Alizarine  Blue  SKY 

Alizarine  Green  SS 

Alizarine  Red  WS 


Alkali  Blue  6B,  3R 
Alkali  Vi;ilet  LR,  O 
Alkaline  Blue  GB,  3R 
Alkaline  Fast  Red  R 
AlkaUnc  Violet  CA 
Alphanol  Black  BG,  R 
Alphanol  liluc  BR 
Anthracene  Acid  Green 
Anthracene  Red 
Archil  Substitute  G 
Azo  Acid  Black  B,  G,  BL 
Azo  Acid  Blue  B 
Azo  Acid  Carmine  B 


CLASSIFICATION   OF   DYES 


546 


Azo  Acid  Magenta  G,  6B 
Azo  Acid  Yellow 
Azo  Carmine 
Azo  Flavine 
Azo  Red  A 
Benzyl  Blue  B,  S 
Benzyl  Green  B 
Benzyl  Violet  4B,  lOB 
Brilliant  Acid  Green  6B 
Brilliant  Black  B 
Brilliant  Croceine  3B 
Brilliant  Milling  Blue  B 
Brilliant  Milling  Green  B 
Brilliant  Sulphon  Azurine 
Brilliant  Wool  Blue  G 
Brilliant  \Vool  Blue  RB 
Chroniogen  I 
Chromotrope  FB,  SB 
Chromotrope  G,  2R,  2B 
Citronine  00 
Cloth  Fast  Blue  R,  G,  B 
Cloth  Red  BA 
Cochineal  Red  A 
Cochineal  Scaret  PS 
Croceine   AZ 
Croceine  Orange  G 
Croceine  Scarlet  3B 
Curcumeine 
Cyanine  B 

Diamond  Black  F,  NG 
Eosin 

Fast  Green  CR 
Fast  Red  A 
Fast  Scarlet  B 
Fast  Yellow  Y 
Flavazine  T 
Formyl  Blue  B 
Formyl  Violet  S4B,  lOB 
Guinea  Green  B 
Guinea  Violet  4B 
Indian  Yellow  G,  R,  FF 
Indocj'anine,  B 
Indigo  Carmine 
Lanacyl  Blue  2B,  R 
Lancyl  Xavy  Blue  B 
Lancyl  Violet  B 
Lazuline  Blue  R 
Light  Green  SF 
Mandarine  G 
Martins  Yellow 
Metanil  Y'ellow 


Milling  Red  G 

Mordant  Yellow  O 

Naphthalene  Blue  B,  D 

Naphthalene  Green  V 

Naphthaline  Acid  Black  4B 

Naphthaline  Yellow 

Naphthol  Blue  G,  R 

Naphthol  Blue  Black 

Naphthol  Dark  Green  G 

Naphthol  Red  O,  S 

Naphthol  Yellow  S 

Naphthyl  Blue  Black  N,  FB 

Naphthylamine  Blacks 

Neutral  Blue  for  Wool 

Neutral  Wool  Black  G,  B 

New  Mctoria  Blue  B 

Orange  II,  ENZ,  R 

Orange  GT,  G 

Palatine  Black  4B 

Palatine  Red  A 

Patent  Blue  A,  V,  N,  L 

Phenylamine  Black  4B,  T 

Phloxine 

Ponceau  3R,  3RB 

Quinoline  Yellow 

Red  Violet  4RS 

Rhodamine  B,  G 

Rocelline 

Scarlet  R,  6R 

Silk  Red  G 

Sorbine  Red 

Sulphon  Acid  Blue  B,  R 

Sulphon  Azurine  D 

Sulphon  Black  R,  4BT 

Sulphon  Blue  Black 

Sulphon  Brown  R 

Suljihon  Cyanine  G,  GR 

Sulphon  Cyanine  Black  B 

Tartrazine 

Thiocarmine  R 

Tropaeoline  G,  00 

Victoria  Rubine  O,  G 

Victoria  Scarlet  2R,  6R 

Victoria  Violet  4BS 

Wool  Black  6B,  4FB,  GR,  N4B 

Wool  Blue  5B,  2B,  R  and  G 

Wool  Blue  N,  R,  SR,  S 

Wool  Green  S 

Wool  Jet  Black  2B,  3B 

Wool  Red  B,  BG 

Wool  Violet  lOB,  6B 


548 


DYEING   CF   FABRICS  CONTAINING   MIXED   FIBRES 


(E)  Substantive  Dyes  Which  Dye  Cotton  in  a  Cold  Bath  and  Leave  the  Wool  White 


Anthraquinone  Black 
Benzo  Blue  2B,  3B,  RW 
Beazo  Chrome  Browns 
Beazo  Cj^anine  3B 
Banzo  Dark  Green 
Benzo  Fast  Scarlet  4BS 
Benzo  Sky  Blue 
Benzo  Violet  R 
Brilliant  Azurine  B 
Brilliant  Benzo  Blue  6B 
B.illiant  Geranine  G 
Brilliant  Orange  G 
Brilliant  Purpurine  R 
Chicago  Blue  6B 
Chloramine  Orange  G 
Chloramine  Yellow 
Chrysophenine  G 
Columbia  Black  HWD 
Columbia  Blue  G,  R 
Congo  Red 
Congo  Rubine 
Cotton  Red  A 
Cotton  Yellow  R 
Curcum'.ne  S 
Diamine  Black  BH,  HW 
Diamine  Blue  2B 
Diamine  Brown  S 
Diamine  Fast  Blue  FFB 
Diamine  Fast  Yellow  A,  B 
Diamine  Green  G 
Diamine  Heliotrope  G,  B,  O 
Diamine  Xitrazol  Brown  G 
Diamine  Orange,  G,  D 
Diamine  Pure  Blue  A 
Diamine  Purpurine  6B 


Diamine  Red  lOB 
Diamine  Rose  GD 
Diamine  Sky  Blue  FF 
Diamine  \'iolet  Red 
Dianil  Black  PR,  PG,  CR 
Dianil  Blue  G,  B,  R 
Dianil  Orange  G 
Dianil  Brown  R 
Dianil  Yellow  2R 
Diazo  Black  B,  BHN 
Direct  Black  VT 
Direct  Deep  Black  E 
Direct  Yellow  R 
Erica  BX,  2GX 
Grounding  Black  for  Cotton 
Heliotrope  2B 
Melanogene  Blue  B 
Mikado  Orange  G 
Oxamine  Blue  3R,  A,  B 
Oxamine  Brown  M 
Oxamine  Claret  M 
Oxamine  Garnet  M 
Oxamine  Red 
Oxamine  Violet 
Oxy  Diamine  Red  S 
Oxy  Diamine  Violet  B,  G,  R 
Phenamine  Blue  G,  B,  R 
Pluto  Black  BS,  G,  FR,  F 
Pyramine  Orange  R 
Salmon  Red 
Sulphine  A,  N 
Thiazine  Brown  G,  R 
Thiazole  Yellow  R 
Zambesi  Black  D 


12.  After-treatment  of  Union  Dyeings. — Where  substantive  d^'es  are 
used  on  union  goods  it  is  sometimes  possible  to  obtain  an  increased  fast- 
ness to  light  and  washing  by  giving  the  dyed  goods  an  after-treatment  with 
a  bath  containing  bluestone  or  chrome  or  a  mixture  of  the  two  salts.  This 
after-treatment  is  carried  out  by  treating  the  rinsed  goods  for  one-half 
hour  in  a  fresh  boiling  bath  with  1  to  3  per  cent  of  bluestone,  ^  to  1  per  cent 
of  chrome,  and  i  to  1  per  cent  of  acetic  acid. 

The  wool  in  union  goods  dyed  with  substantive  colors  maj'^  at  times 
be  topped  with  basic  dyes  in  order  to  increase  the  brilliancy  of  the  shade. 
This  is  usually  done  in  a  fresh  cold  or  lukewarm  bath  with  the  addition  of  a 
little  acetic  acid,  and  not  using  over  ^  per  cent  of  the  basic  dye,  as  other- 


EXPERIMENTAL  STUDIES 


547 


wise  the  color  will  probably  rub.     It  will  generally  also  be  found  that  some 
of  the  basic  dye  will  go  on  the  cotton  and  brighten  its  color. 

13.  The  Dyeing  of  Wool-plush. — Wool-plush  is  a  half-wool  fabric  con- 
sisting of  a  cotton  backing  and  a  wool  pile  and  the  construction  of  the 
fabric  requires  cotton  in  both  the  warp  and  the  filling.  This  cotton  is 
usually  dyed  in  the  warp  and  skein  previous  to  weaving,  and  the  wool  is 
dyed  afterwards  in  the  piece.  For  the  latter  purpose  acid  dyes  are  gen- 
erally employed,  or  certain  of  the  natural  wood  dyes  (in  the  case  of  certain 
brown  shades  Archil  and  Sandal- wood  are  employed).  In  some  of  these 
plush  fabrics  the  wool  is  woven  in  pattern  effect  so  that  the  cotton  backing 
is  not  entirely  covered.  In  such  cases  the  cotton  must  be  dyed  the  same 
color  as  the  wool,  and  consequently  is  not  dyed  until  after  the  piece  is 


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Fig.  269. — Machine  for  Sizing  and  Finishing  Silk. 

woven.  For  this  purpose  one  of  the  two-bath  dyeing  processes  given  above 
may  be  employed.  The  dyes  used  should  be  easily  leveling  colors  and  have 
good  fastness  to  rubbing  and  light. 

Wool-plush  is  mostly  dyed  in  an  open-width  machine  so  as  not  to 
injure  and  crease  the  pile  surface,  though  sometimes  in  the  case  of  light- 
weight plush  the  dyeing  is  done  in  the  rope  form,  and  the  ordinary  dye-tub 
and  winch  may  be  used  running  the  goods  with  the  pile  surface  uppermost. 

14.  Experimental.  Exp.  208.  Action  of  Acid  Dyes.— Take  a  skein  of  wool-cotton 
yarn  and  place  it  in  a  bath  containing  2  per  cent  of  Formyl  Violet  S4B,  4  per  cent  of 
sulphuric  acid  and  10  per  cent  of  glaubersalt;  boil  for  one-half  hour,  wash  and  dry. 
It  will  be  found  that  the  acid  colors  only  dye  the  wool  in  an  acid  bath.* 

*  The  skeins  of  union  yarn  (wool-cotton)  to  be  employed  in  these  experiments  may 
be  conveniently  made  by  simply  taking  a  5-gram,  test  skein  of  woolen  yarn  and  a  5- 
gram  test  skein  of  cotton  yarn  and  dyeing  them  together  as  a  10-gram  skein.  Or 
the  skems  may  be  made  in  a  rather  better  manner  by  reeling  together  a  strand  of  wool 


548  DYEING   OF   FABRICS   CONTAINING   MIXED   FIBERS 

Exp.  209.  Action  of  Basic  Dyes.— Dye  a  skein  of  wool-cotton  yarn  in  a  bath  contain- 
ing 2  per  cent  of  Metliylene  Blue  and  10  per  cent  of  glaubersalt;  boil  for  one-half  hour, 
then  wash  and  dry.  It  will  be  found  that  the  basic  colors  dye  only  the  wool  in  a 
neutral  bath,  the  cotton  only  being  slightly  tinted.  Mordant  a  skein  of  wool-cotton 
yarn  in  a  bath  containing  4  per  cent  of  tannin;  work  at  180*  F.  for  fifteen  minutes,  then 
leave  in  the  bath  without  1.  rther  heating  for  one-half  hour,  then  queeze  and  pass  into 
a  bath  containing  2  per  cent  of  tartar  emetic,  work  cold  for  fifteen  minutes,  then  wash 
well,  and  pass  into  a  bath  containing  2  per  cent  of  Methylene  Blue  and  10  per  cent  of 
glaubersalt;  boU  for  one-half  hour,  then  wash  and  dry.  It  will  now  be  found  that  both 
the  wool  and  the  cotton  have  become  dyed.  Observe  if  both  of  the  fibers  are  dyed  to 
the  same  shade  and  same  tone  of  color. 

Exp.  210.  Action  of  Substantive  Dyes. — (a)  Dyeing  the  Wool  and  Cotton  Alike. 
Dye  a  skein  of  wool-cotton  yarn  in  a  bath  containing  2  per  cent  of  Thioflavine  S  and  10 
per  cent  of  glaubersalt.  Boil  for  one-half  hour,  then  wash  and  dry.  Compare  the  color 
obtained  on  the  wool  with  that  on  the  cotton. 

(b)  Dyeing  the  Cotton  Darker  than  the  Wool.  Dye  a  skein  of  wool-cotton  yarn  in  a 
bath  containing  2  per  cent  of  Diamine  Fast  Yellow  A,  10  per  cent  glaubersalt,  and  1  per 
cent  of  soda  ash,  at  160°  F.  for  one-half  hour,  then  wash  and  dry.  Notice  if  the  two 
fibers  are  the  same  in  color,  or  if  the  cotton  is  darker  than  the  wool.  The  use  of  an 
alkaline  bath  causes  the  color  to  go  on  the  cotton  better  than  the  wool,  as  a  rule.  Borax 
may  also  be  used  for  making  the  bath  slightly  alkaline,  instead  of  soda  ash,  and  .with 
less  injury  to  the  wool  fiber  in  the  boiling  bath. 

(c)  Dyeing  the  Wool  Darker  than  the  Cotton. — Dye  a  skein  of  wool-cotton  yarn  in  a 
bath  containing  2  per  cent  of  Diamine  Gold  and  10  per  cent  of  glaubersalt.  Boil  for 
one-half  hour,  then  wash  and  dry,  and  compare  the  olor  obtained  on  the  cotton  and 
wool.  These  colors,  as  a  rule,  dye  better  on  the  wo  1  at  the  boil  than  on  the  cotton, 
while  they  are  taken  up  in  larger  proportion  by  the  cotton  at  lower  temperatures. 

Exp.  211.  Acid  Dyes  which  Leave  the  Cotton  White. — Use  a  skein  of  wool-cotton 
yarn  in  a  bath  containing  10  per  cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and 
1  per  cent  of  dyestuff  indicated  below;  enter  at  140°  F.,  gradually  raise  to  the  boil 
and  dye  for  one-half  hour  at  that  temperature. 

Acid  Magenta  Azo  Acid  Black 

Acid  Violet  4RS  Guinea  Violet  4B 

Patent  Blue  V  Cloth  Red  GA 

Naphthol  Yellow  S  Ahzarine  Blue  SAE 

Orange  G  Azo  Fuchsine  G 

Acid  Green  Fast  Light  Yellow  G 

After  dyeing  at  the  boil  for  one-half  hour,  add  2  per  cent  more  of  sulphuric  acid  and 
continue  boiling  for  fifteen  minutes.  The  material  should  be  washed  directly  after 
being  dyed  in  order  to  prevent  bleeding  into  the  cotton. 

Exp.  212.  Dyeing  Wool  and  Leaving  Cotton  White  with  Mordant  Color,  Using 
Chromium  Fluoride. — Dye  a  union  skein  of  wool  and  cotton  in  a  bath  containing  10  per 
cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and  2  per  cent  of  Alizarine  Red  WS; 
enter  at  140°  F.,  gradually  raise  to  the  boil  and  dye  for  one-half  hour;  then  add  2  per  cent 

yarn  and  one  or  more  of  cotton  yarn  to  make  up  a  5-gram  or  10-gram  test  skein  as  desired. 
The  number  of  strands  of  the  two  fibers  should  be  so  selected  that  about  equal  amounts 
of  both  wool  and  cotton  are  present  in  test  skein,  unless  for  special  reasons  a  different 
proportion  is  desired.  Strips  of  undyed  white  cloth  containing  woolen  and  cotton 
yarns  may  also  be  used  for  making  the  tests. 


EXPERIMENTAL  STUDIES  549^ 

of  chromium  fluoride  and  continue  boiling  for  fifteen  minutes.  Wash  well  and  dry. 
Several  of  the  acid  alizarine  colors  may  be  dyed  in  this  manner. 

Exp.  213.  Developing  with  Chrome. — Dye  a  skein  of  union  yarn  in  a  bath  containing 
10  per  cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid  and  4  per  cent  of  Chromotrope 
FB;  enter  at  140°  F.,  gradually  raise  to  the  boil  and  dye  for  one-half  hour;  then  lift 
the  material  from  the  bath  and  add  1  per  cent  of  chrome  and  continue  dyeing  for  fif- 
teen minutes  at  the  boil.  Dye  another  skein  in  the  same  manner  as  the  first,  but  instead 
of  adding  the  chrome  to  the  dyebath  directly,  rinse  the  skein  and  pass  into  a  fresh  bath 
containing  2  per  cent  of  chrome  and  oil  for  fifteen  minutes;  then  wash  and  dry.  Com- 
pare the  two  methods  for  the  amount  of  color  tinting  the  cotton  and  the  shade  obtained 
on  the  wool. 

Exp.  214.  Acid  Dyes  Taken  up  by  the  Wool  in  a  Neutral  Bath  and  not  Dyeing  the 
Cotton. — Dye  a  skein  of  union  yarn  in  a  bath  containing  1  per  cent  of  Alkali  Blue  and 
10  per  cent  glaubersalt  and  2  per  cent  of  borax;  enter  at  140°  F.,  raise  to  the  boil  and  dye 
for  one-half  hour;  rinse  slightly  and  pass  into  a  bath  containing  5  per  cent  of  sulphuric 
acid,  and  boil  for  fifteen  minutes.  Wash  well  and  dry.  Dye  a  second  skein  of  union 
yarn  in  a  bath  containing  10  per  cent  of  glaubersalt  and  1  per  cent  of  Blue  for  Half-wool. 
Dye  as  usual  for  one-half  hour  then  wash  and  dry.  Dye  a  third  skein  of  union  yarn  in  a 
bath  containing  10  per  cent  of  glaubersalt  and  1  per  cent  of  Chrome  Black  B;  dye  in 
the  usual  manner  for  one-half  hour;  then  wash  well  and  dry.  Dye  a  fourth  skein  of 
union  yarn  in  the  same  manner  with  1  per  cent  of  Orange  II.  These  dyes  tint  the  cotton 
but  very  little  even  in  neutral  baths. 

Exp.  215.  Substantive  Dye  Applied  in  an  Acid  Bath. — Dye  a  skein  of  union  yarn  in  a 
bath  containing  1  per  cent  of  Chrysophenine,  10  per  cent  of  glaubersalt,  and  4  per  cent 
of  acetic  acid;  enter  at  140°  F.,  and  gradually  raise  to  the  boil  and  dye  for  one-half  hour. 
Wash  and  dry  and  it  will  be  found  that  both  the  wool  and  the  cotton  are  dyed.  Such 
colors  are  useful  for  dyeing  in  connection  with  the  acid  dyes  which  have  to  be  used  in  an 
acid  bath. 

Exp.  216.  Production  of  Two-color  Effects  in  Two  Baths  with  Acid  and  Substantive 
Dyes. — Take  a  skein  of  wool-cotton  yarn  and  dye  it  in  a  bath  containing  15  per  cent  of 
sodium  bisulphate  and  1  per  cent  of  the  following  dyestuffs : 

Naphthol  Yellow  S  Acid  Green 

Lanafuchsine  SG  Naphthol  Black  (use  6  per  cent  of  this) 

Rhodamine  B  Azo  Red 

Formyl  Violet  S4B  Cyanole 

Alizarine  Lanacyl  Blue  B  Brilliant  Cochineal  2R 

After  dyeing  these  skeins,  rinse  them  in  a  bath  containing  a  small  amount  of  ammonia ; 
then  wash  and  dye  in  a  second  bath  containing  about  300  cc.  of  water,  20  per  cent  of 
glaubersalt  and  1  per  cent  each  of  the  following  dyes: 

Diamine  Fast  Yellow  A  on  Lanafuchsine  SG. 

Diamine  Fast  Yellow  A  on  Formyl  Violet  S4B. 

Diamine  Fast  Yellow  A  on  Acid  Green. 

Benzo  Blue  2B  on  Naphthol  Yellow  S. 

Benzo  Blue  2B  on  Rhodamine  B. 

Diamine  Orange  D  on  Alizarine  Lanacyl  Blue  B. 

Diamine  Orange  D  on  Naphthol  Black. 

Diamine  Violet  N  on  Azo  Red. 

Diamine  Violet  N  on  Cyanole. 

Diamine  Catechine  G  on  Brilliant  Cochineal  2R. 

The  second  bath  is  to  be  used  cold.  After  dyeing  rinse  in  a  bath  containing  a  small 
amount  of  acetic  acid,  then  wash  in  fresh  water. 


550  DYEIxNG   OF   FABRICS   CONTAINING   MIXED   FIBERS 

Exp.  217.  Another  Method  of  Producing  Two-color  Effects  with  Two  Baths. — (a) 

Dye  two  skeins  of  wool-cotton  yarn  with  1  per  cent  of  Thioflavine  S  and  10  per  cent 
glaubersalt  in  the  usual  manner.  Wash,  and  dye  one  of  the  skeins  in  a  bath  containing 
1  per  cent  of  Formyl  Violet  lOB,  and  dye  the  second  tkein  in  a  bath  containing  1  per 
cent  of  Azo  Rubine.  In  neutral  baths  these  acid  dyes  tint  the  cotton  tlightly  but 
dye  the  wool. 

(o)  Dye  two  skeins  of  wool-cotton  yarn  with  1  per  cent  of  Diamine  Sky  Blue  in  the 
usual  manner;  wash,  and  dye  one  of  the  skeins  in  a  bath  containing  1  per  cent  of  Orange 
II,  and  the  second  skein  in  a  bath  containing  1  per  cent  of  Naphthol  Yellow  S. 

(c)  Dye  two  skeins  of  wool-cotton  yarn  in  a  bath  of  1  per  cent  of  Diamine  Bordeaux, 
wash,  and  dye  one  of  the  skeins  with  1  per  cent  Naphthol  Yellow  S,  and  the  second  skein 
with  1  per  cent  of  Formyl  Violet  lOB. 

Exp.  218.  Producing  Two-color  Effects  in  One  Bath. — Prepare  a  bath  containing 
300  CO.  of  water,  20  per  cent  of  glaubersalt,  and  1  per  cent  of  Alizarine  Lanacyl  Blue  R; 
dye  a  sktin  of  wool-cotton  yam  in  this  bath  at  140°  to  boil  for  one-half  hour.  Then 
lift  the  skein,  remove  the  heat  and  add  to  the  bath  1  per  cent  of  Diamine  Fast  Yellow^  A, 
and  dye  for  one-half  hour  more  without  raising  the  temperature  of  the  bath.  Wash  and 
dry.  Repeat  this  experiment,  using  Naphthol  Yellow  S,  Orange  ENZ,  Azo  Rubine,  and 
Rhodaminc  for  the  wool  colors,  and  Diamine  Brown  M,  Diamine  Blue  2B,  Diamine 
Orange  D,  and  Diamine  Black  RO  respectively  for  the  cotton  color. 

Exp.  219.  Production  of  Two-color  Effects  with  Developed  Dyes. — Prepare  a  bath 
containing  6  per  cent  of  Primuline,  20  per  cent  of  common  salt,  and  2  per  cent  of  soda; 
dye  a  skein  of  wool-cotton  yarn  in  this  bath  in  the  usual  manner;  rinse,  and  pass  through  a 
cold  bath  containing  6  per  cent  of  sodium  nitrite  and  5  per  cent  of  sulphuric  acid  for  fifteen 
minutes;  rinse  slightly  and  pass  through  a  third  bath  containing  1  per  cent  of  beta- 
naphthol  solution ;  work  cold  for  ten  minutes.  Then  wash  well  and  soap  in  a  warm  dilute 
soap  bath.  Next  dye  the  wool  in  a  bath  containing  1  per  cent  of  Cyanole  and  15  per 
cent  of  glaubersalt  and  4  per  cent  of  sulphuric  acid;  enter  at  140°  F.,  raise  to  the  boil 
and  dye  for  one-half  hour.  Wash  and  dry.  To  obtain  a  blue  on  the  cotton,  dye  in  the 
same  manner  as  above  but  use  1  per  cent  Diamine  Black  BH,  diazotize,  and  develop 
with  1  per  cent  of  Naphthylamine  Ether.  Wash  and  soap,  and  dye  the  wool  as  before 
with  1  per  cent  of  Naphthol  Yellow  S.  To  obtain  a  black  on  cotton,  dye  as  before 
with  6  per  cent  of  Diamine  Black  EH,  diazotize,  and  develop  with  1  per  cent  of  pheny- 
lene  diamine.     Wash  and  soap,  and  dye  the  wool  with  1  per  cent  Azo  Rubine  as  before. 

Exp.  220.  Dyeing  Wool  Black  and  Cotton  in  Colors. — Dye  five  skeins  of  wool-cotton 
yarn  with  5  per  cent  of  Acid  Black  4BL,  4  per  cent  of  sulphuric  acid  and  20  per  cent  of 
glaubersalt;  boil  for  one-half  hour  and  then  add  2  per  cent  more  of  sulphuric  acid 
and  boil  for  fifteen  minutes  longer.     Wash  well  and  squeeze. 

(a)  Dye  the  first  skein  in  a  bath  containing  1  per  cent  Mikado  Orange  and  10  per 
cent  of  glaubersalt  at  1G0°  F.  for  one-half  hour;  then  wash  well  and  dry. 

{b)  Dye  the  second  skein  in  a  bath  containing  1  per  cent  of  Brilliant  Benzo  Blue 
6B  and  10  per  cent  of  glaubersalt  for  one-half  hour  at  160°  F.     Wash  well  and  dry. 

(c)  Dye  the  third  skein  in  a  bath  containing  1  per  cent  of  Direct  Yellow  R  and  10 
per  cent  of  glaubersalt  for  one-half  hour  at  160°  F.  Wash  well  and  dry. 
I  (d)  Mordant  the  fourth  skein  in  a  bath  containing  2  per  cent  of  tannic  acid  at  160°  F. 
for  one-half  hour;  squeeze  and  work  in  a  cold  bath  containing  1  per  cent  of  tartar  emetic 
for  fifteen  minutes.  Wash  and  dye  in  a  bath  containing  5  per  cent  Brilliant  Rhoduline 
B  and  5  per  cent  of  Auramine  and  3  per  cent  of  alum.  Dye  for  one-half  hour  at  180° 
F.     Wash  well  and  dry. 

(c)  Mordant  the  fifth  skein  with  tannic  acid  and  tartar  emetic  as  above  described; 
wash,  and  dye  in  a  bath  containing  \  per  cent  of  Turquoise  Blue  G  and  3  per  cent  of 
alum  for  one-half  hour  at  180°  F.     Wash  well  and  dry. 


EXPERIMENTAL  STUDIES  551 

Eyp.  221.  Dyeing  Fancy  Shades  on  Wool  and  Leaving  Cotton  White. — Take  test 
skeins  of  wool-cotton  yarn  and  dye  them  in  a  bath  containing  300  cc.  of  water,  20  per 
cent  of  glaubersalt,  4  per  cent  of  sulphuric  acid,  and  the  respective  amounts  of  the 
dycstuffs  named;  enter  at  140°  F.,  gradually  raise  to  the  boil,  dye  at  that  temperature 
for  one-half  hour,  then  add  2  per  cent  more  of  sulphuric  acid,  and  continue  boiling  for 
fifteen  minutes.     Finally  wash  well  and  dry.     Use  the  following  combinations  of  dyes: 

(1)  0.05  per  cent  .\lizarine  Blue  SAE; 
0.15  per  cent  Fast  Light  Yellow  G; 
0.07  per  cent  Azo  Crimson  S; 

(2)  0.03  per  cent  A  izarine  Blue  SAE; 
0.25  per  cent  Fast  Light  Yellow  G; 
0.15  per  cent  Azo  Crimson  S; 

(3)  0.50  per  cent  Alizarine  Blue  SAE; 
1.00  per  cent  Fast  Light  Yellow  G; 
0.70  per  cent  Azo  Crimson  S; 

(4)  0.32  per  cent  Alizarine  Blue  SAE; 
0.14  per  cent  Fast  Ligh   Yellow  G; 
0.18  per  cent  Azo  Crimson  S; 

(5)  0.30  per  cent  Alizarine  Blue  SAE 
0.75  per  cent  Fast  Light  Ye  ow  G ; 
0.20  per  cent  Azo  Fuchsine  G ; 

(6)  0.50  per  cent  Alizarine  Blue  SAE; 
0.03  per  cent  Orange  II; 

0.02  per  cent  Fast  Light  Yellow  G ; 

(7)  2.50  per  cent  Victoria  Navy  Blue  B; 
0.15  per  cent  Orange  II; 

(8)  6.00  per  cent  Acid  Black  4BL; 

(9)  0  10  per  cent  Alizarine  Blue  SAE; 
0.08  per  cent  Azo  Fuchsine  G; 
0.07  per  cent  Fast  Light  Yellow  G; 

(10)  0.08  per  cent  Alizarine  Blue  SAE; 
0.17  per  cent  Fast  Light  Yellow  G; 
0.08  per  cent  Azo  Crimson  S. 

Exp.  222.  Dyeing  Cotton  in  a  Cold  Bath  and  Leaving  Wool  Undyed. — Take  test 
skeins  of  wool-cotton  yarn  and  dye  them  in  baths  containing  300  cc.  of  water,  10  cc.  of 
soap  solution  (50  grams  per  liter)  and  1  per  cent  each  of  the  following  dyes: 

Erica  BN  Heliotrope  2B 

Brilliant  Orange  S  Columbia  Black  HWD 

Chrysophenine  Zambesi  Black  D 

Chicago  Blue  6B  Columbia  Blue  G 

Enter  cold  and  work  for  one-half  hour  without  heating.     Then  wash  well  and  dry. 

By  this  method  the  cotton  becomes  dyed  almost  as  well  as  if  in  a  boiling  bath,  while 
the  wool  is  only  dyed  to  a  very  slight  degree. 

Exp.  223.  Dyeing  the  Cotton  Black  and  the  Wool  in  Colors. — Dye  test  skeins  of 
wool-cotton  yarn  in  baths  containing  250  cc.  of  water,  6  per  cent  of  Columbia  Black  FB, 
20  per  cent  of  glaubersalt,  and  3  per  cent  of  soda  ash;  dye  for  half  an  hour  at  140  to 
160°  F.,  then  rinse  well  and  squeeze.  Dye  five  skeins  in  this  manner.  Now  dye  the 
wool  with  acid  colors,  as  follows:  U.se  a  bath  containing  300  cc.  of  water,  10  per  cent  of 
glaubersalt,  6  per  cent  of  sul{)huric  acid,  and  1  per  cent  each  of  the  following  dyes  ■ 


552  DYEING   OF   FABRICS   CONTAINING    MIXED   FIBERS 

Formyl  Violet  lOB  Naphthol  Yellow 

Acid  Violet  Acid  Green 

The  fifth  skein  is  to  be  left  with  the  wool  undyed. 

Exp.  224.  Dyeing  Cotton  in  a  Cold  Bath  with  Substantive  Colors,  and  Subsequently 
Dyeing  the  Wool  with  Basic  Colors. — Dye  five  test-skeins  of  union  yarn  in  baths  contain- 
ing 300  cc.  of  water,  10  cc.  of  soap  solution  (containing  50  grams  of  soap  per  liter),  and 
1  per  cent  of  Chrj'sophenine.  Enter  cold,  and  work  for  one-half  hour  without  heating; 
then  wash  well.  This  will  dye  the  cotton  a  yellow  color  and  leave  the  wool  practically 
white.  Now  dye  these  skeins  in  baths  containing  300  cc.  of  water,  3  per  cent  of  acetic 
acid,  and  the  following  respective  dyestuffs;  enter  cold  and  gradually  raise  to  180°  F., 
and  continue  at  that  temperature  for  one-half  hour,  then  wash  well  and  dry, 

(1)  Use  5  per  cent  of  Methylene  Blue. 

It  will  be  found  that  the  basic  color  at  this  percentage  is  mostlj-  taken  up  by  the  cot- 
on,  the  substantive  dyestufT  on  the  cotton  acting  as  a  mordant  towards  the  basic  color. 

(2)  Use  1  per  cent  of  Methylene  Blue. 

It  will  be  found  that  the  wool  is  now  dyed  to  some  extent  by  the  basic  color  as  well 
as  the  cotton. 

(3)  2  per  cent  of  Methylene  Blue. 

This  should  dye  the  wool  a  blue  and  the  cotton  a  green  color. 

(4)  Use  1  per  cent  of  Methyl  Violet  4R. 

(5)  U.se  2  per  cent  of  Methyl  Violet  4R. 

Dye  another  set  of  five  union  skeins  in  the  same  manner  as  above  described,  using 
1  per  cent  of  Chicago  Blue  6B  in  the  first  bath  for  the  dyeing  of  the  cotton,  and  then  in 
the  second  baths  use  respectively: 

(1)  I  per  cent  Safranine. 

(2)  2  per  cent  of  Safranine. 

(3)  5  per  cent  of  Auramine. 

(4)  2  per  cent  of  Auramine. 

(5)  2  per  cent  of  Rhodaniine. 

Exp.  225.  Dyeing  the  Cotton  in  a  Cold  Bath  with  Substantive  Colors,  and  Subse- 
quently Dyeing  the  Wool  with  Acid  Colors. — Dye  five  test  skeins  of  union  j-arn  in  baths 
containing  300  cc.  of  water,  10  cc.  of  soap  solution  (containing  50  grams  of  soap  per  liter), 
and  1  per  cent  of  Chrysophenine.  Enter  cold  and  work  for  half  an  hour  without  heating, 
then  wash  well.  This  will  dye  the  cotton  a  yellow  color  and  leave  the  wool  practically 
white.  Now  dye  these  skeins  in  baths  containing  300  cc.  of  water,  4  per  cent  of  sul- 
phuric acid,  and  the  following  respective  dyestuffs;  enter  at  140°  F.,  gradually  raise  to 
the  boil,  and  continue  at  that  temperature  for  one-half  hour;  then  wash  well  and  dry. 

(1)  Use  i  per  cent  Alizarine  Blue  SAE. 

(2)  Use  2  per  cent  of  .\lizarine  Blue  SAE. 

(3)  Use  1  per  cent  Azo  Crimson  S. 

(4)  Use  1  per  cent  Azo  Fuchsine  G. 

(5)  Use  2  per  cent  Acid  Black  4BL. 

Dye  another  set  of  five  vmion  skeins  in  the  same  manner  as  above  described,  using 
1  per  cent  Chicago  Blue  in  the  first  bath  for  the  dyeing  of  the  cotton,  and  then  in  the 
second  baths  use  respectively: 

(1)  1  per  cent  of  Naphthol  Y'ellow. 

(2)  ^  per  cent  Alizarine  Blue  SAE  and  |  per  cent  Naphthol  Yellow. 

(3)  1  per  cent  Acid  Black  4BL. 

(4)  5  per  cent  Orange  II. 

(5)  1  per  cent  Azo  Crimson  S. 


EXPERIMENTAL   STUDIES  553 

Exp.  226.  Dyeing  Two-color  Effects  in  One  Bath  with  Substantive  and  Acid  Dyes.— 

(1)  Dye  a  skein  of  union  yarn  in  a  bath  containing  IjOO  co.  of  water,  20  per  cent  salt,  2 
per  cent  of  Mikado  Yellow  and  2  per  cent  of  Guinea  Violet;  enter  at  140°  F.,  gradually 
raise  to  the  boil  and  dye  at  that  temperature  for  one-half  hour;  wash  well  and  dry. 

(2)  Repeat  the  above  test,  but  dye  at  a  temperature  of  100°  F.  for  one-half  hour; 
wash  and  dry. 

(3)  Dye  a  skein  of  union  yarn  in  a  bath  containing  300  cc.  of  water,  20  i^er  cent  of 
salt,  2  per  cent  of  Curcumine  8,  and  2  per  cent  of  Ponceau  2RB;  enter  at  140°  F., 
gradually  raise  to  the  boil,  and  dye  at  that  temperature  for  one-half  hour;  wash  well 
and  dry. 

(4)  Repeat  the  above  experiment,  using  as  the  dyestuffs  2  per  cent  of  Curcu- 
mine S  and  1  per  cent  of  Rhodamine. 

(5)  Repeat  the  above  experiment,  using  as  the  dyestuffs  2  per  cent  of  Guinea  Green  B 
and  2  per  cent  Mikado  Yellow. 

Exp.  227.  Dyeing  Single  Shades  on  Both  Wool  and  Cotton  in  One  Bath. — (1)  Dye 
a  skein  of  union  yarn  in  a  bath  containing  300  cc.  of  water,  20  per  cent  of  glaubersalt, 
2  per  cent  of  Benzopurpurine  4B,  0.8  per  cent  Congo  Rubine,  and  2  per  cent  of  Fast 
Red  A;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  dye  at  that  temperature  for 
one-half  hour;   wash  well  and  dry. 

(2)  Dye  a  skein  of  union  yarn  in  the  same  manner  as  above  using  as  the  dyestuffs 
0.15  per  cent  Curcumine  S,  0.15  per  cent  Zambesi  Black  D,  and  0.03  per  cent  Curcumeine 
extr  \ . 

(3)  Use  0.45  per  cent  Curcumine  S,  0.45  per  cent  Zambesi  Black  D,  and  0.09  per  cent 
Curcumeine  extra. 

(4)  Use  1.4  per  cent  Curcumine  S,  1.4  per  cent  Zambesi  Black  D,  and  0.3  per  cent 
Curcumeine  extra. 

(5)  Use  0.15  per  cent  Zambesi  I^lack  D,  0.15  per  cent  Columbia  Fast  Blue  2G, 
0,10  per  cent  Wool  Blue  2B,  and  0.04  per  cent  Wool  Black  6B. 

(6)  Use  1.2  per  cent  Columbia  Violet  R,  0.2  per  cent  Columbia  Blue  R,  and  0.28 
per  cent  Guinea  Violet  4B. 

(7)  Use  0.8  per  cent  Zambesi  Black  D,  1.2  per  cent  Mikado  Orange  4R0,  0.3  per  cent 
Curcumine  S,  0.15  per  cent  Mandarine  G  extra,  and  0.12  per  cent  Curcumeine  extra. 

(8)  Use  1.8  per  cent  Columbia  Brown  R,  2  per  cent  Mikado  Orange  4R0,  and  0.4 
per  cent  Mandarine  G  extra. 

(9)  Use  0.5  per  cent  Curcumine  S,  0.1  per  cent  Zambesi  Black  D,  and  0.1  per  cent 
Curcumeine  extra. 

(10)  Use  2  per  cent  Curcumine  S,  0.4  per  cent  Zambesi  Black  D,  and  0.2  per  cent 
Curcumeine  extra. 

15.  Dyeing  of  Wool-silk  Materials, — Wool  and  silk  fibers  are  not  spun 
together  into  yarns  owing  to  the  very  different  physical  characters  of  the 
two  fibers,  but  there  are  quite  a  variety  of  fabrics  made  from  separate 
yarns  of  wool  and  silk.  Sometimes  plain  woven  fabrics  of  this  character 
are  to  be  met  with  in  which  the  warp  is  of  wool  and  the  filling  of  silk 
(or  vice  versa)  or  again,  the  two  fibers  may  be  used  to  produce  pattern 
effects,  and  there  are  fabrics  for  suitings  and  dress-goods  made  principally 
of  wool  (or  worsted)  with  silk  effect  threads.  Knitted  fabrics  are  also 
made  from  wool  and  silk  for  underwear  and  hosiery. 

A  widely  used  fabric  of  wool  and  silk  is  known  under  the  name  of 
Gloria,  and  it  is  largely  employed  in  the  making  of  umbrella  cloth,  rain- 


554  DYEING    OF   FABRICS   CONTAINING    MIXED   FIBERS 

coat  material,  and  ladies'  dress-goods.  Another  fabric  known  as  Poplin 
has  a  silk  warp  and  a  fine  wool  filling;  there  is  also  a  half-silk  Cashmere 
and  Bombazine,  both  of  which  have  silk  warp  and  wool  filling.  Crepe  de 
Chine  is  a  similar  fabric  of  great  popularity. 

Frequentl}'  the  silk  yarn  employed  in  such  fabrics  has  not  been  com- 
pletely boiled-off  previous  to  weaving,  so  that  it  still  contains  a  consideral^le 
amount  of  silk-glue.  On  this  account  it  becomes  necessar>'  to  boil-off 
the  goods  before  dj-eing,  and  this  is  done  in  a  strong  neutral  soap  bath  at  a 
temperature  of  about  190°  F.  The  use  of  alkali  and  a  high  temperature 
must  be  avoided  in  order  to  preser\'e  the  wool  from  injur}'.  If  spun  silk 
has  been  used  or  if  the  silk  has  been  boiled-off  previous  to  weaving,  of 
course,  the  process  of  boiling-off  the  piece  is  to  be  omitted. 

The  dyeing  properties  of  wool-silk  materials  are  far  different  from  those 
of  wool-cotton  goods,  owing  to  the  fact  that  both  wool  and  silk  possess 
approximately  the  same  relations  to  dj^estuffs.  That  is  to  say,  those  dyes 
which  can  be  applied  to  silk  are  also  applicable  to  wool  and  in  about  the 
same  manner;  there  are,  however,  certain  dyes  which  are  satisfactory  for 
wool  ^hich  do  not  dye  well  on  silk.  In  most  cases  both  the  wool  and  the 
silk  are  dyed,  though  one  fiber  may  receive  a  heavier  or  a  somewhat  differ- 
ent tone  of  color.  Then  there  are  certain  cases  where  the  wool  takes  up 
the  dye  alone,  leaving  the  silk  practically  unstained. 

In  the  dyeing  of  wool-silk  goods  the  temperature  of  the  dyebath  plays 
an  important  part  in  the  production  of  uniform  colors;  as  a  general  rule, 
the  wool  dyes  best  in  a  boiling  bath  while  the  silk  dj-es  better  at  lower 
temperatures  or  even  in  a  cold  bath,  so  that  by  dyeing  in  an  unheated  bath 
it  is  sometimes  possible  to  dj-e  the  silk  while  leaving  the  wool  practically 
undyed. 

For  the  dyeing  of  wool-silk  materials  the  acid,  basic,  and  substantive 
colors  are  the  principal  ones  employed  at  the  present  time.  In  former 
years  the  natural  dyewoods  were  used  considerably,  but  such  satisfactory 
dyes  are  now  available  among  the  above-named  classes  that  it  is  seldom 
that  the  mordant  dyes  are  used  for  this  class  of  material.  The  following 
dj'eing  processes  come  into  consideration: 

(1)  Dyeing  with  Acid  Dyes  to  Produce  a  Uniform  Color  on  Both  Fibers. — 
Prepare  a  dyebath  containing  the  well-dissolved  color  with  the  addition  of 
5  to  10  per  cent  of  glaubersalt  and  1  to  3  per  cent  of  sulphuric  acid  (5  to 
10  per  cent  of  sodiimi  bisulphate  may  be  used  instead).  Run  the  goods 
for  one  hour,  starting  at  160°  F.  and  gradually  bringing  to  the  boil.  If 
the  color  does  not  come  up  to  a  match  on  the  silk  it  may  be  shaded  with  a 
basic  dye  by  allowing  the  bath  to  cool  down,  add  the  necessary  well-dis- 
solved basic  dj'estuff  and  run  the  goods  for  fifteen  minutes,  then  rinse  well. 

(2)  Dyeing  with  Acid  Dyes,  Leaving  the  Wool  Undyed. — Prepare  the 
bath  with  5  per  cent  of  acetic  acid  and  run  the  goods  in  the  cold  bath  for 


DYEING   WOOL-SILK  GOODS 


555 


one-half  to  one  hour.     In  carrying  out  this  process  a  proper  selection  of 
dyes  must  be  made  to  obtain  the  l^est  results. 

(3)  Dyeing  with  Alkali  Blue. — Prepare  the  bath  with  10  per  cent  of 
borax  and  dye  for  one  hour  at  180  to  195°  F.  Then  rinse  and  run  the 
goods  through  a  lukewarm  bath  containing  5  per  cent  of  sulphuric 
acid. 

(4)  Dyeing  with  Acid  Dyes,  Leaving  the  Silk  Undyed. — Prepare  the 
bath  with  20  per  cent  of  acetic  acid  and  dye  at  the  boil  for  one  hour.  Rinse 
well  and  then  treat  the  goods  for  one-half  hour  at  100°  F.  in  a  bath  contain- 
ing wheat  bran,  which  serves  to  clear  up  the  silk.  Then  rinse  well  again 
and  scroop  by  passing  through  a  bath  containing  5  per  cent  of  acetic  acid 


i'lG.  270. — Machine  for  Finishius  Half-silk  Pieces. 


and  drying  without  washing.     In  this  case  also  it  is  necessary  properly  to 
select  the  dyestuffs  in  order  to  obtain  good  results. 

(5)  To  Produce  Two-color  Effects. — Dye  the  wool  as  above  described, 
leaving  the  silk  white,  and  then  dye  the  silk  in  a  different  color  by  the  use 
of  suitable  basic  or  acid  colors,  employing  a  bath  containing  3  to  5  per  cent 
of  acetic  acid  at  a  temperature  of  70  to  80°  F. 

(6)  Dyeing  with  Basic  Dyes  to  Produce  a  Uniform  Color  on  Both  Fibers. — 
Use  a  neutral  bath  and  dye  at  the  boil  for  one  hour.  Most  of  the  basic 
colors  (exceptions  are  Magenta  and  Chrysoidine)  dye  the  silk  much  heavier 
than  the  wool  if  an  acid  bath  is  used  (3  per  cent  of  sulphuric  acid  and  10 
per  cent  of  glaubersalt) ,  so  this  latter  process  may  be  used  either  for 
shading  the  silk  or  for  the  production  of  two-color  effects. 

(7)  Dyeing  with  the  Substantive  Colors. — Use  a  bath  containing  10  to 
20  per  cent  of  glaubersalt  and  dye  at  the  boil  for  one  hour.     To  obtain  a 


556  DYEING  OF  FABRICS  COXTAIXIXG   MIXED   FIBERS 

uniform  shade  it  is  necessarj'  to  make  a  proper  selection  of  the  dyes  to  be 
used,  and  in  some  eases  it  is  necessary-  to  boil  the  goods  for  a  considerable 
time  in  order  to  even  up  the  color.  Should  the  wool  come  up  too  light 
add  1  to  2  per  cent  of  acetic  acid  and  continue  the  boihng. 

In  the  dj-eing  of  suiting  cloths  with  white  silk-effect  threads,  in  order 
to  obtain  the  silk  clear  and  bright  it  is  essential  that  the  dyebath  should 
have  a  low  acidity  and  a  high  temperature.  In  this  class  of  goods  owing 
to  ihe  liigh  degree  of  fastness  usually  recjuired  the  number  of  dyestuifs 
which  are  suitable  is  rather  Limited.  The  acid  chrome  colors  are  to  be 
reconunended  for  this  purpose,  especially  those  which  dye  by  the  one-bath 
meta-chroxne  method,  though  the  clearest  silk-effect  threads  are  probably 
obtained  by  first  chroming  the  goods  and  then  dyeing  in  a  separate  bath. 
The  goods  are  mordanted  in  the  usual  manner  •^'ith  2  to  3  per  cent  of 
chrome  and  2  to  3  per  cent  of  tartar,  or  with  1  to  2  per  cent  of  chrome  and 
1  to  3  per  cent  of  formic  acid,  then  rinsed  and  dyed  in  a  fresh  bath  with  the 
addition  of  2  to  5  per  cent  of  acetic  acid  or  of  5  per  cent  of  anmionium 
acetate  in  the  case  of  light  shades.  The.  goods  are  entered  at  100°  F., 
gradually  raised  to  the  boil  and  boiled  for  two  hours.  With  hea\'y  shades 
it  is  usually  required  after  boiling  for  one  hour  to  add  2  to  4  per  cent  of 
acetic  acid  in  order  to  exhaust  the  bath.  After  dj-eing  the  goods  are  well 
rinsed  and  soured  off  with  acetic  or  formic  acid. 

"VMiere  heaw  shades  ai'e  dj-ed,  and  especially  in  the  case  of  black,  it  is 
almost  impossible  to  prevent  the  silk  from  becoming  slightly  stained.  In 
order  to  clear  the  silk  a  number  of  methods  are  reconmiended.  The 
goods  may  be  run  in  a  fresh  bath  for  twenty  minutes  at  175°  F.  containing 
1  oz.  anmionium  oxalate  per  ICO  gallons  of  Hcjuor,  then  rinsed.  Or  a  more 
effective  strippmg  may  l^e  obtained  by  using  a  bath  containing  2  ozs. 
anmionium  acetate  per  10  gallons  of  lic}Uor.  By  this  method,  however, 
some  of  the  color  on  the  wool  will  also  be  stripped  and  this  must  be  allowed 
for.  In  the  case  of  some  blacks  the  silk  assumes  a  slightly  bluish  gray 
shade,  which  may  be  removed  by  treatment  vdth.  hydrosulphite  as  follows: 
Use  a  bath  containing  3  gallons  acetic  acid  (30  per  cent)  and  5  gallons 
hydrosulphite  solution  (prepared  from  1  gallon  of  sodium  bisulphite  66° 
Tw.,  1  gallon  cold  water,  and  1  lb.  zinc  dust;  stir,  settle  and  use  clear 
solution)  for  100  lbs.  of  goods.  Run  in  .tliis  bath  at  120  to  140°  F.  for 
one-half  hour,  then  rinse  well  and  sour  off  in  a  bath  containing  5  per  cent 
of  sulphuric  acid  and  rinse  again. 

16.  Classification  of  Dyes  for  Wool-silk  Fabrics. — Most  of  the  acid 
dyes  give  approximately  the  same  color  on  both  fibers,  but  certain  of 
these  dyes  behave  differently  on  the  two  fibers.  The  following  may 
prove  of  practical  interest: 

(a)  Acid  dyes  which  only  slightly  stain  the  silk  in  a  boiling  acid  bath. 

(6)  Acid  dyes  which  dye  only  the  silk  in  an  acid  bath  at  120°  F. 


CLASSIFICATION   OF   DYES 


557 


(c)  Substantive  dyes  which  dye  both  silk  and  wool    approximately 
alike  in  a  boiling  bath. 

(d)  Substantive  dyes  which    only  slightly  stain  the  silk  in  a  neutral 
boiling  bath. 

(e)  Basic  dyes  useful  for  dyeing  or  shading   the  silk  to  produce  shot 
effects  in  an  acetic  acid  bath  at  120°  F.,  the  wool  being  scarcely  stained. 


(A)    Acid   Dyes  not  Dyeing  the   Silk  in  Boiling  Acid  Bath 


Acid  Green 
Acid  Magenta 
Acid  Violet  3RS 
Acid  Yellow  G 
Acid  Yellow  AT 
Alizarine  Blue  SAP 
Amaranth 

Azo  Acid  Carmine  B 
Azo  Cochineal 
Azo  Crimson  L,  S 
Azo  Fuchsine  B,  G 
Azo  Rubine  SG 
Azo  Wool  Blue  C 
Azo  Wool  Violet  7R 
Benzyl  Red  S 
Bordeaux  S 
Brilliant  Cochineal  2R 
Brilliant  Scarlet  4R 
Chromotrop  2R,  2B 
Cochineal  Scarlet  PS 
Crj^stal  Scarlet  6R 
Cyanole  FF 
Direct  Rose  BN,  GN 
Eosamine  B 
Eosin  3G,  BN 


Fast  Light  Yellow  3G 
Fast  Red  NS 
Fast  Yellow  S 
Flavazine  T 
Guinea  Red  4B 
Indigo  Extract 
Indigo  Carmine 
Lanafuchsine  SG 
Mars  Red  G 
Metanil  Yellow 
Naphthol  Green  B 
Naphthol  Red  C,  O 
Naphthol  Yellow 
Naphthylamine  Black 
New  Coccine 
New  Fast  Yellow  R 
Orange  II 
Orange  G 
Ponceau  S  for  Silk 
Sorbine  Red 
Tartrazine 
Victoria  Rubine  O 
Victoria  Scarlet  3R 
Victoria  Violet  4BS 


(B)  Acid  Dyes  not  Dyeing  the  Wool  in  Cold  Acid  Bath 


Acid  Green 

Acid  Magenta 

Acid  Violet  4B,  6BN,  HW 

Acid  Violet  6BS 

Alkali  Violet  LR 

Amaranth  B 

Azo  Acid  Yellow 

Azo  Orseille  2B 

Brilliant  Croceine 

Brilliant  Milling  Blue  B 

Brilhant  Milling  Green  B 

Croceine  AZ 

Fast  Acid  Eosine  G 

Fast  Acid  Green  BN 


Fast  Acid  Magenta  G 
Fast  Acid  Phloxine  A 
Fast  Blue  B,  R 
Fast  Red  extra 
Formyl  Blue  B 
Formyl  Violet  S4B,  lOB 
Guinea  Green  B 
Guinea  Violet  4B 
Lanafuchsine  SG 
Mandarine  G 
Methyl  Blue 
Milling  Red  FR 
Milling  Yellow  00 
Naphthalene  Green  V 


558 


DYEING   OF  FABRICS  CONTAINING   MIXED   FIBERS 


Naphthol  Blue  Black 
Naphthol  Blue  G 
Naphthol  Red  O 
Naphthylamine  Black  ESN 
Ponceau  lORB,  4RB,  2GB 
Rosazeine  B 
Tetra  Cyanole  V 


Tropeoline  RPN 
Victoria  Rubine  O 
Violamine  G,  R,  B 
Water  Blue  B 
Wool  Blue 
Wool  Blue  TB 


(C)  Acid  Dyes  Which  Dye  Wool  and  Silk  about  the  Same  Shade  in  a  Strongly 

Acid  Bath 


Acid  Rhodamine  R 

Acid  Rosamine 

Acid  Violet  4RN,  3BN,  7B 

Agalraa  Green  B 

Alkali  Blue 

Alkali  Violet  LR 

Anthracene  Red 

Anthracite  Black  BR 

Azo  Acid  Yellow 

Azo  Cardin  1  G 

Azo  Carmine  G 

Azo  Coccine  2R 

Azo  Flavine 

Azo  Orseille  2B 

Azo  Yellow  O 

Benzyl  Green  B 

Bordeaux  extra 

Brilliant  Acid  Green  6B 

Brilliant  Croceine 

Brilliant  Millin    Blue  B 

Brilliant  Milling  Green  G 

Brilliant  Silk  Blue  lOB,  7B 

China  Yellow  B 

Chinaldine  Yellow 

Chrysoin 

Cloth  Red  3GA 

Croceine  AZ 

Curcumeine 

Cyanole  Fast  Green  G 

Double  Brilliant  Scarlet  G 

Emin  Red 

Fast  Acid  Vio'et  R,  B 

Fast  Blue  B,  R 

Fast  Brown  G,  GR 

Fast  Light  Green 

Fast  Light  Yellow  G 

Fast  Red 

Fast  Scarlet 

Formyl  Blue  B 


Formyl  Violet  S4B 

Gloria  Black  B 

Guinea  Green  B,  G 

Guinea  Violet  4B 

Indian  Yellow 

Indocyanine  B 

Irisamine  G 

Light  Blue  for  Silk 

Light  Green  SF 

Mandarine  G 

Martius  Yellow 

Metanil  Yellow 

Naphthylamine  Black  4B 

Neptune  Blue  R,  B,  BG 

Neptune  Green  S,  SG 

Neutral  Wool  Black  B,  G,  4E 

Orange  II 

Orange  EN 

Palantine  Black  4BS,  MZ 

Patent  Blue,  A,  V 

Phloxine 

Ponceau  3RB 

Quinoline  Yellow 

Resorcine  Brown 

Rhodamine  B 

Rocceline 

Rosazeine  B 

Silk  Black  4BF 

Silk  Red  N,  G,  R 

Sulphon  Cyanine  Black 

Tetra  Cyanole  A 

Victoria  Black  B,  G 

Victoria  Blue  B 

Victoria  Yellow  O 

Wool  Black  GR 

Wool  Blue  SL 

Wool  Green  S 

Wool  Violet  lOB 


CLASSIFICATION   OF   DYES 


559 


.(D)   Substantive  Dyes  Dyeing  Silk  and  Wool  Alike 


Acetylene  Blue  6B 
Benzo  Chrome  Brown  B,  R 
Benzo  Dark  Green  B,  2G 
Benzo  Fast  Black 
Benzo  Fast  Orange  S 
Benzo  Fast  Red  L,  GL 
Benzo  Fast  Scarlet  GS 
Benzo  Green  2B,  G 
Benzopurpurin  4B 
Benzo  Rhoduline  Red  B 
Benzo  Sky  Blue 
Benzo  Violet  R,  RL 
Brilliant  Benzo  Blue  6B 
Brilliant  Benzo  Green  B 
Brilliant  Congo  R 
Brilliant  Diamine  Bordeaux  R 
Brilliant  Purpurine  R 
Carbide  Black  E 
Chicago  Blue  6B,  B,  RW,  R 
Chloramine  Violet  R 
Chloramine  Yellow  M 
Chlorantine  Lilac  B 
Chrysophenine  G 
Congo  Blue  BX 
Congo  Brown  G,  R 
Congo  Orange,  G,  R 
Congo  Orange  R 
Congo  Sky  Blue 
Cotton  Yellow  CH 
Cupranil  Brown  B 
Delta  Purpurine  5B 
Diamine  Black  HW 
Diamine  Blue  RW 
Diamine  Bordeaux  S 
Diamine  Brilliant  Blue  G 
Diamine  Brown  3G,  R,  V,  M 
Diamine  Cutch  G 
Diamine  Dark  Green  N 
Diamine  Fast  Brown  G,  R 
Diamine  Fast  Red  F 


Diamine  Fast  Yellow  FF 

Diamine  Gray  G 

Diamine  Green  B,  G,  CL 

Diamine  New  Blue  R,  G 

Diamine  Orange  B,  F 

Diamine  Red  B 

Diamine  Red  4B 

Diamine  Rose  BB,  GD 

Diamine  Scarlet  B,  3B 

Diamine  Sky  Blue  FF 

Diamine  Steel  Blue  L 

Diamine  Yellow  CP 

Diamineral  Brown  G 

Dianil  Black  CR,  N,  R,  E 

Dianil  Blue  G,  B,  R 

Dianil  Brown  3G0,  R,  BD 

Dianil  Claret  Red  G,  B 

Dianil  Orange  G 

Dianil  Red  4B 

Dianil  Yellow  3G,  R,  2R 

Diazo  Blue  Black 

Direct  Brown  R 

Direct  Deep  Black  E,  EW,  R 

Bisect  Light  Blue 

Direct  Orange  G,  R 

Direct  Sky  Blue 

Geranine  G 

Oxy  Diamine  Black  JW,  JB 

Oxy  Diamine  Black  SOOO 

Oxy  Diamine  Blue,  B,  R,  G 

Oxy  Diamine  Brown  G,  3GN 

Oxy  Diamine  Violet  B,  R 

Oxy  Diamine  Yellow  TZ 

Pluto  Brown  R 

Pluto  Orange  G 

SUk  Black 

Sulphon  Cyanine  G,  GR,  3R 

Thioflavine  S 

Zambesi  Black  D 


Prolonged  boiling  causes  these  dyes  to  go  more  strongly  on  the  wool,  while  the  silk 
is  dyed  to  best  advantage  at  about  140°  F. 


(E)  Substantive  Dyes  not  Dyeing  the  Silk 


Erica  BN 
Columbia  Blue  G,  R 


Columbia  Violet  R 
Heliotrope  2B 


560 


DYEING   OF   FABRICS  CONTAINING   MIXED   FIBERS 


(F)  Basic  Dyes  for  Shading  the  Silk,  not  Dyeing  the  "W90I 


Auramine 
Bismarck  Brown 
Brilliant  Green 
Brilliant  Rhoduline  Red  B 
Brilliant  Safranine 
China  Green 
Chrjsoidine  F 
Cotton  Green 
Ethj'l  Green 
Janus  Black  O 
Janus  Blue  G,  R 
Janus  Brown  R,  B 
Janus  Gray  B 
Janus  Green  G,  B 
Janus  Red  B 
Janus  Yellow  G,  R 
Jute  Coal  Black  F,  R 
Malachite  Green 
Methyl  Violet 
Methylene  Blue 


Methylene  Green 
Methylene  Violet 
New  Blue  D 
New  Methylene  Blue  N 
Paraphosphine  G 
Rhodamine  B,  G,  6G 
Rhoduline  Blue  R 
Rhoduline  Heliotrope  B 
Rhoduline  Red  B,  G 
Rhoduline  Sky  Blue  2B 
Rhoduline  Violet 
Rosolane  O,  T 
Rubine 
Safranine 
Solid  Green 
Tannin  Heliotrope 
Tannin  Orange  R 
Thioflavine  T 
Turquoise  Blue  2B  G 
Victoria  Blue 


17.  Silk-cotton  Materials. — There  are  a  large  variety  of  silk  fabrics 
which  are  constructed  in  part  with  cotton  yarns.  The  fabric  is  usually 
so  woven  that  the  cotton  appears  only  on  the  back,  thus  leaving  an  all-silk 
surface  on  the  other  side.     Familiar  examples  of  such  fabrics  are  ribbons, 


Fig.  271.— Machine  for  Foularding,  Stretching  and  Drying. 


satins,  brocades,  silk  upholstery  materials,  etc.  Silk  knitted  goods  are 
also  made  up  with  considerable  cotton  at  times;  hosiery  and  underwear, 
for  instance,  may  have  a  cotton  thread  spliced  with  the  silk  and  knitted 


DYEING  SILK-COTTON   FABRICS  561 

together;  or  in  the  case  of  hosiery,  part  of  the  fabric  may  be  all-silk  (the 
leg  part)  while  other  parts  are  of  cotton  (the  foot  and  upper  portion). 
The  cotton  used  with  the  silk  may  be  the  ordinary  variety  or  more  gen- 
erally it  may  be  mercerized  cotton.  In  the  latter  case  the  distinction 
between  the  two  fibers  is  less  apparent,  as  the  mercerized  cotton  has  con- 
siderable luster  and  silky  feel.  Artificial  silk  is  also  very  largely  used 
in  admixture  with  true  silk  both  in  knitted  fabrics  and  in  a  wide  variety 
of  fancy  fabrics.  As  artificial  silk  is  a  cellulose  fiber,  and  its  dyeing  prop- 
erties are  practically  the  same  as  cotton,  it  will  be  considered  in  this  same 
connection. 

Silk-cotton  fabrics  are  more  generally  required  to  be  dyed  so  that 
both  the  fibers  have  the  same  color,  though  at  times  the  object  is  to  pro- 
duce two  color  effects,  the  silk  being  dyed  one  color  while  the  cotton  may  be 
dyed  in  a  strongly  contrasting  color.  On  referring  to  the  relations  of  these 
two  fibers  to  the  various  classes  of  dyes  it  will  be  noticed  that  the  basic 
colors  dye  the  silk  directly,  leaving  the  cotton  undyed  unless  it  has  been 
previously  mordanted  with  tannin  and  tartar  emetic.  The  acid  dyes  also 
dye  the  silk  directly  from  acid  baths,  in  some  cases  even  in  the  cold,  while 
they  leave  the  cotton  less  stained  even  than  with  the  basic  dyes.  The 
substantive  colors,  on  the  other  hand,  in  many  cases  d^^e  both  fibers  alike, 
though  some  'of  the  substantive  colors  may  be  dyed  on  the  cotton  while 
leaving  the  silk  practically  undyed.  Some  of  the  diazotized  and  developed 
colors  also  may  be  used  as  they  dye  both  fillers  practically  alike.  The 
mordant  dyes  have  no  application  for  silk-cotton  fabrics. 

18.  Dyeing  of  Silk-cotton  Fabrics. — Material  of  this  character  usually 
comes  into  the  hands  of  the  dyer  in  a  form  all  readj-  to  be  dyed;  if,  however, 
the  fabric  has  been  prepared  from  raw  silk,  it  will  be  necessary  to  first 
boil-off  the  silk  before  dyeing.  This  is  done  in  the  customary  manner  by 
boiling  in  a  bath  containing  about  30  per  cent  of  soap,  and  according  to 
the  amount  of  gum  on  the  fiber  the  treatment  should  last  from  one-half  to 
two  hours.  In  cases  where  light  delicate  colors  are  to  be  dyed  it  may  be 
necessary  to  bleach  the  goods,  and  this  is  usually  done  by  steeping  in  a 
bath  of  hydrogen  peroxide  in  the  customary  manner  of  bleaching  silk  by 
this  process. 

In  the  dyeing  of  silk-cotton  materials  the  character  of  the  fabric  has 
much  to  do  with  the  method  to  be  employed.  In  the  case  of  satins,  atlas 
cloth,  etc.,  in  which  only  the  silk  appears  on  the  right  side  of  the  goods,  the 
dyeing  of  the  silk  is  the  most  important  feature,  the  color  of  the  cotton  is  of 
subsidiary  importance,  and  it  often  matters  very  little  as  to  whether  the 
cotton  is  exactly  the  same  shade  as  the  silk  or  not.  In  fabrics  in  which  the 
silk  appears  as  a  pattern  on  a  cotton  background,  or  as  silk-effect  threads 
in  an  otherwise  all-cotton  fabric,  the  lustrous  silk  fiber  will  show  a  contrast- 
ing effect  even  if  dyed  the  same  shade  with  the  dull-appearing  cotton, 


562  DYEING    OF   FABRICS   COXTAIXlXd    MIXED    FIBERS 

and  this  contrast  can  be  further  accentuated  by  dyeing  the  two  fibers  in 
different  colors.  In  some  cases  even  one  of  the  fibers  may  be  left  undyed 
as  a  pattern  of  effect  thread. 

If  it  is  desired  to  dye  only  the  silk  and  leave  the  cotton  white,  the  dyeing 
is  best  carried  out  with  suitable  acid  colors  in  a  strong  acetic  (or  formic) 
acid  bath  cold  or  lukewarm.  If,  on  the  other  hand,  it  is  desired  to  leave 
the  silk  white  and  dye  only  the  cotton,  then  suitable  substantive  dyes  are 
selected  which  dye  only  on  the  cotton  in  a  strongly  alkahne  bath.  At 
the  present  time,  owing  to  the  simphcity  of  the  methods  of  application, 
the  substantive  dyes  are  by  far  the  most  important  colors  for  use  on  silk- 
cotton  goods;  next  to  these  are  the  acid  dyes,  while  the  basic  dyes  are  of 
very  minor  importance.  Formerly  this  material  was  quite  extensively 
dj^ed  by  mordanting  the  cotton  with  tannin  and  tartar  emetic,  rinsing,  and 
dyeing  with  basic  colors,  first  cold  and  then  warm,  so  that  both  fibers  will 
be  evenly  covered.  This  method,  however,  is  now  scarcely  ever  employed 
in  practice. 

Another  process  devised  bj'  IMoyret  was  as  follows:  The  fabric  was 
padded  with  Turkey-red  oil  neutraHzed  with  ammonia  and  then  dried 
for  twenty-four  to  forty-eight  hours.  The  excess  of  oil  was  then  removed 
by  treatment  with  a  cold  dilute  bath  of  soda  ash,  after  which  the  goods 
were  washed  and  brightened  with  hydrochloric  acid  and  well  washed  again. 
On  dyeing  the  material  now  with  basic  colors  it  will  be  found  that  the 
cotton  will  take  up  the  color  as  well  as  the  silk;  also  the  oil  gives  the  goods 
a  desirable  feel.  After  dyeing,  the  goods  are  dried  without  washing,  as 
the  color  on  the  cotton  is  not  fast  to  washing. 

19.  Dyeing  Processes. — While  the  one-bath  process  of  dyeing  silk- 
cotton  goods  is  probably  the  one  most  in  vogue  at  the  present  time,  there 
are  besides  a  variety  of  other  processes  which  may  be  enumerated  as  follows: 

(1)  Dyeing  only  the  Silk,  Leaving  the  Cotton  White. — Use  a  bath  contain- 
ing a  suitable  acid  dyestuff,  together  with  10  per  cent  of  acetic  acid;  run 
the  goods  for  about  one  hour  at  al)out  175°  F.  "Wash  well,  and  if  necessary 
to  whiten  up  the  cotton  and  free  it  from  stains  pass  through  a  very  weak 
cold  bath  of  chloride  of  lime,  then  sour  in  weak  acetic  acid  and  wash 
thoroughly. 

(2)  Dyeing  with  Substantive  Colors  so  that  both  Fibers  are  of  the  Sajne 
Shade. — Prepare  a  bath  containing  dyestuff,  10  to  20  per  cent  of  glaubersalt 
and  5  to  10  per  cent  of  soap;  run  for  one  hour  at  180°  F.,  then  rinse  and 
brighten  with  acetic  acid.  A  proper  selection  of  dyes  must  be  made  in 
this  case  to  produce  the  desired  effect,  as  many  of  the  substantive  colors 
dye  best  on  the  silk,  while  a  few  give  heavier  shades  on  the  cotton.  In 
many  cases  it  will  be  necessary  to  shade  the  silk  in  a  second  bath  con- 
taining a  suitable  acid  dyestuff  with  the  addition  of  5  per  cent  of  acetic 
acid. 


DYEING   SILK-COTTON   FABRICS 


563 


(3)  Dyeing  with  Substantive  Colors  so  that  the  Silk  is  Left  Undyed. — 
Prepare  the  dyebath  with  the  properly  selected  dyestuff  with  the  addition 
of  20  per  cent  of  soap  and  5  per  cent  of  soda  ash,  and  dye  for  one  hour  at 
190°  F.  Rinse  well  and  brighten  with  acetic  acid.  Only  certain  of  the 
substantive  dyes  are  suitable  for  this  process. 

(4)  Production  of  Tivo-color  Effects. — The  cotton  may  first  be  dyed  as 
described  above  with  a  substantive  dye  in  an  alkaline  bath,  and  then 


Fig.  272.— Three-Bowl  Heavy  Friction  Calender.     (Mather  &  Piatt). 


the  silk  is  dyed  with  a  suitable  basic  dyestuff  at  85°  F.  in  a  bath  containing 
4  ozs.  acetic  acid  per  10  gallons  of  liquor.  The  basic  color  will  also  be  taken 
up  to  some  extent  by  the  dyed  cotton,  as  the  substantive  dye  will  act  as  a 
mordant  for  the  basic  color,  so  that  due  allowance  must  be  made  for  this 
fact  in  the  production  of  the  effects  desired.  In  another  process  the  cotton 
may  be  dyed  first  with  the  proper  substantive  color  and  then  the  silk  is 
dyed  in  a  fresh  bath  with  an  acid  dye  in  a  boiling  bath  containing  5  per 


564  DYEING  OF  FABRICS  CONTAINING   MIXED  FIBERS 

cent  of  sulphuric  acid.  Of  course  in  this  case  it  will  be  necessary  to  use 
a  substantive  dye  for  the  cotton  that  is  fast  to  acid  (cross-dyeing).  Also 
the  goods  must  be  well  washed  after  dyeing  and  soaped  in  order  to  neu- 
tralize the  acid,  which  might  otherwise  tender  the  cotton. 

Plush  fabrics  consisting  of  a  silk  pile  surface  and  a  cotton  backing  form 
one  of  the  most  important  silk-cotton  materials.  These  goods  usually  have 
to  be  dj^d  in  special  apparatus  in  order  to  preserve  the  silk  pile  from  injury 
and  streaks.  In  this  case  the  cotton  is  very  often  first  dyed  in  the  warp 
with  suitable  sulphur  dyes  before  weaving,  and  then  the  silk  is  afterwards 
dyed  in  the  piece,  using  acid  dyes  or  if  very  fast  colors  are  desired.  Indigo 
or  other  vat  dyes  may  be  used,  or  even  certain  of  the  mordant  colors  may 
be  applied  to  the  silk.  A  similar  fabric  is  made  from  a  tussah  silk  pile  and 
a  cotton  backing  and  after  dyeing  (or  sometimes  before  dj^eing)  the  goods 
are  subjected  to  certain  mechanical  treatments  whereby  the  pile  surface 
is  given  an  effect  resembling  a  fur  or  pelt.  These  goods  are  extensively 
used  for  cloakings,  trmimings,  etc.,  as  artificial  fur  cloth.  Goods  of  this 
character  often  present  difficult  problems  to  the  dj^er  and  finisher  in  order 
to  produce  a  uniform  and  satisfactory  color  and  also  to  obtain  the  particular 
character  of  finish  on  the  pile  surface  that  is  desired. 

Blacks  are  sometimes  produced  on  silk-cotton  goods  (especially  ribbons 
and  satins)  by  the  use  of  the  sulphur  colors.  The  color  obtained  is  very 
fast  and  is  almost  equal  in  qualit}'-  to  that  of  Aniline  Black.  The  dye- 
bath  is  prepared  as  follows:  For  10  gallons  of  hquor  use  1  to  2  lbs.  Sulphur 
Black,  1  to  2  lbs.  sodium  sulphide,  3  to  4  lbs.  glucose,  3  ozs.  soda  ash,  3  ozs. 
Turkey-red  oil  and  |  to  1  lb.  glaubcrsalt  (desiccated).  Dj^e  the  goods  for 
one  to  one  and  one-half  hours  at  a  temperature  just  under  the  boil,  then 
squeeze,  rinse  in  cold  water  containing  a  little  soda  ash  and  then  rinse 
again  in  warm  water.  Then  treat  the  goods  for  one-half  hour  in  a  boiling 
bath  containing  3  per  cent  of  chrome,  2  per  cent  lactic  acid  and  5  per 
cent  acetic  acid ;  rinse  and  dye  in  a  fresh  boiling  bath  containing  Log- 
wood extract  and  soap,  using  a  little  Fustic  if  necessary  for  toning. 
Another  method  recommended  is  to  use  the  Sulphur  Black  in  a  vat 
containing  sodium  hydrosulphite  and  glaubersalt. 

Attempts  have  also  been  made  to  dj^e  Aniline  Black  on  silk-cotton 
goods  such  as  ribbons  and  satins,  and  more  or  less  success  has  been  achieved, 
but  the  conditions  of  dj^eing  have  to  be  so  accurately  regulated  in  order  to 
obtain  proper  results  and  prevent  injury  to  the  silk  that  the  processes  have 
never  proved  to  be  of  practical  value. 

20.  Classification  of  Dyes  for  Silk-cotton  Materials. — The  following 
tables  of  dyestuffs  give  the  principal  colors  and  their  properties  with 
respect  to  the  dyeing  of  silk-cotton  fabrics: 


CLASSIFICATION   OF   DYES 


565 


(A)  Substantive  Dyes  Which  Leave  the  Silk  Undyed  at  200°  F. 


Acetylene  Blue  3B,  6B 

Benzo  Blue  2B 

Benzo  Chrome  Black  Blue  B 

Benzo  Fast  Pink  2BL 

Benzo  Fast  Scarlet  5BS,  GS 

Benzo  Sky  Blue 

Brilliant  Azurine  B,  5G,  5R 

Brilliant  Benzo  Blue  6B 

Chicago  Blue  6B 

Chloramine  Orange  G 

Chloramine  Yellow  GG 

Chlorantine  Blue  B 

Chlorantine  Lilac  B 

Chlorantine  Orange  TR 

Chlorantine  Pure  Blue 

Chlorantine  Red  4B,  8B 

Chlorantine  Rose 

Chlorantine  Yellow  JJ,  JQ 

Columbia  Black,  HWD 

Columbia  Blue  G,  R 

Columbia  Fast  Blue  2G 

Columbia  Fast  Scarlet  4B 

Congo  Fast  Blue  HW 

Congo  Sky  Blue 

Cotton  Brown  RN 

Cotton  Orange  RG 

Cotton  Red  4B 

Curcumine  S 

Diamine  Black  BH 

Diamine  Blue  2B 

Diamine  Fast  Scarlet  2G,  4BN,  6BS 

Diamine  Fast  Yellow  A 

Diamine  Orange  D,  G 

Diamine  Pure  Blue  A 

Diamine  Rose  T 


Diamine  Sky  Blue  FF 
Diauil  Bhic  G,  B,  R 
Dianil  Dark  Blue  R 
Dianil  Direct  Yellow  S 
Dianil  Orange  G 
Diazo  Black  BHN 
Diazo  Blue  Black 
Direct  Blue  2B 
Direct  Gray  R,  B 
Direct  Indigo  Blue  BN,  BK 
Direct  Light  Blue 
Direct  Sky  Blue 
Direct  Violet  N 
Direct  Yellow  R 
Direct  Yellow  T 
Erica 

Mikado  Golden  Yellow  8G 
Mikado  Orange 
Mikado  Orange  GO,  4RO 
Mikado  Yellow 
Oxamine  Black 
Oxamine  Blue  B,  GN 
Oxamine  Brown  3G 
Oxamine  Copper  Blue  2R 
Oxamine  Dark  Blue  BG 
Oxamine  Pure  Blue  5B 
Oxy  Dianil  Yellow  O 
Phenamine  Bhie  G 
Pluto  Black  F 
Pluto  Black  G  (dev.) 
Pyramine  Orange  R 
Solamine  Blue  B,  R 
Solamine  Blue  FF 
Thiazine  Brown  G,  R 
Zambesi  Black  BR 


(B)  Substantive  Dyes  Which  Dye  Cotton  and  Silk  alike  in  a  Bath  with  Glaubersalt 

and  Soap  at  200°  F. 


Aurophenine   O 

Benzo  Blue  RW 

Benzo  Bordeaux  6B 

Benzo  Brown  D3G 

Benzo  Chrome  Brown  B,  3R 

Benzo  Cyanine  B 

Benzo  Dark  Green  B,  2G 

Benzo  Fast  Black 

Benzo  Fast  Blue  5R 

Benzo  Fast  Red  GL 

Benzo  Fast  Yellow  5GL 


Benzopurpurine  4B 
Benzo  Rhoduline  Red 
Benzo  Violet  RL 
Brilliant  Benzo  Green  B 
Brilliant  Geranine  B 
Brilliant  Purpurine  lOB 
Chicago  Blue  2R 
Chloramine  Violet  R 
Chloramine  Yellow  M 
Chrysamine  G,  R 
Chrysophenine  G 


566 


DYEING   OF   FABRICS   CONTAINING    MIXED   FIBERS 


Columbia  Black  2BW 

Columbia  Black  EA,  WA 

Columbia  Black  Green  D 

Columbia  Orange  R 

Congo  Corinth  B,  G 

Congo  Orange  R 

Congo  Orange  R,  G 

Congo  Rubine 

Cotton  Red  12B,  4B 

Cotton  Yellow  CH 

Cresotine  Yellow  G 

Cupranil  Brown  B,  R,  G 

Delta  Purpurine  5B 

Diamine  Bengal  Blue  G 

Diamine  Black  BH 

Diamine  Black  HW 

Diamine  Blue  RW 

Diamine  Brown  3G,  R,  M 

Diamine  Bordeaux  B,  S 

Diamine  Brilli  nt  Bordeaux  R 

Diamine  Catechine  G,  R,  3G 

Diamine  Dark  Blue  B 

Diamine  Fast  Brown  R,  G 

Diamine  Fast  Red  F 

Diamine  Fast  Yellow  B,  M,  FF,  3G 

Diamine  Gray  G 

Diamine  Green  G,  B,  CL 

Diamine  Orange  B,  F 

Diamine  Purpurine  B,  V 

Diamine  Red  B 

Diamine  Red  5B,  lOB,  D 

Diamine  Rose  BD,  GD,  BG 


Diamine  Scarlet  B,  3B 

Diamine  Steel  Blue  L 

Diamine  A'iolet  Red 

Diamine  Yellow  CP,  N 

Diamineral  Blue  B 

Diamineral  Brown  G 

Diaminogene  B,  BR 

Dianil  Brown  3G0 

Direct  Deep  Black  E,  EW 

Direct  Green  C,  G,  J 

Direct  Orange  G,  R 

Direct  Rose  BN,  GN 

Direct  Yellow  CR 

Geranine  G 

Half  Silk  Black 

Janus  Brown  R 

Janus  Red  B 

Janus  Yellow  R,  G 

Orange  TA 

Oxy  Diamine  Black  JE,  JB,  JW 

Oxy  Diamine  Brown  G,  3GN 

Ox}'  Diamine  Orange  G,  R 

Oxy  Diamine  Yellow  2G,  TZ 

Oxy  Diaminogene  OT,  FFN,  EM 

Pluto  Black  BS 

Pluto  Brown  R 

Pluto  Orange  G 

Salmon  Red 

Thioflavine  S 

Thiazol  Yellow 

Toluylene  Orange  G 

Union  Black  S 


Some  of  these  colors  give  somewhat  different  tones  on  the  two  fibers. 


(C)  Developed  Dyes  Giving  the  Same  Color  on  Silk  and  Cotton 

Columbia  Brown  R  with  toluylene-diamine. 

Diamine  Black  BH  with  beta-naphthol  or  phenylene-diamine. 

Diaminogene  B,  BR  with  beta-naphthol  or  phenylene-diamine. 

Diazo  Bla  k  2B  with  be  .,-naphthol. 

Naphthog  ne  Blue  2R,  4R  with  beta-naphthol. 

Oxy  Diaminogene  OT,  FFN  with  beta-naphthol  or  phenylene-di  m  ne. 

Primuline  with  beta-naphthol. 

Zambesi  Black  D  with  Nrrogene  D. 

Zambesi  Black  D  with  toluylene-diamine. 

Zambesi  Black  2G  with  toluylene-diamine. 

Zambesi  Brown  G,  2G  with  toluylene-diamine. 

Zambesi  Indigo  Blue  R  with  beta-naphthol. 


EXPERIMENTAL  STUDIES 


567 


(D)  Acid  Colors  Which  Dye  only  the  Silk  in  a  Boiling  Acid  Bath 


Acid  Green  BB,  G 
Acid  Green  extra 
Acid  Magenta 
Acid  Maroon  O 
Acid  Violet  6B,  3RS 
Alkali  Violet  LR 
Amaranth  G,  B 
Azo  Fuchsine  G 
Azo  OrseQle  BB 
Azo  Rubine  A 
Azo  Yellow 
Benzyl  Violet  4B 
Blue  B  for  Silk 
Brilliant  Acid  Green  6B 
Brilliant  Croceine 
Brilliant  Milling  Blue  B 
Brilliant  Milling  Green  B 
Brilliant  Orseille  C 
China  Yellow  B 
Croceine  Orange  G,  R 
Croceine  Scarlet  B 
Crystal  Scarlet  6R 
Cyanole  extra 
Fast  Acid  Violet  lOB 
Fast  Green  CR,  W 
Fast  Light  Orange  G 
Fast  Light  Yellow  3G 
Fast  Red  S 


Formyl  Blue  B 

Formyl  Violet  S4B 

P'lavazine  S,  T 

Indian  Yellow  G,  R,  FF 

Induline  B 

Ketone  Blue  4BN 

Metanil  Red  3B 

Milling  Red  G,  R 

Milling  Yellow  O 

Naphthol  Black  2B 

Naphthol  Bhie  R 

Naphthol  Yellow  S 

Naphthylamine  Black  S 

New  Patent  Blue  B,  GA 

Nigrosine 

Orange  II,  ENZ,  GG 

Patent  Blue  V 

Rocceline 

Rosazeine  B 

Scarlet  FR 

Scarlet  R 

Solid  Blue  R 

Tartrazine 

Victoria  Black  B,   G 

Victoria   Rubine  O 

Water  Blue  RB 

Wool  Blue  N,  R 


21.  Experimental.  Exp.  228.  Dyeing  the  Cotton  and  the  Silk  in  One  Color. — Prepare 
a  dyebath  containing  300  cc.  of  water,  0.5  gram  of  olive  oil  soft  soap,  0.1  gram  of  soda 
ash,  and  1  gram  of  salt,  together  with  the  following  percentages  of  the  respective  dyes:* 


2  per  cent  Thioflavine  S 
2  per  cent  Diamine  Orange  B 
1  per  cent  Diamine  Rose  BD 
1  per  cent  Chrysophenine 


2  per  cent  Dianil  Brown  3G0 
2  per  cent  Janus  Red  B 
2  per  cent  Benzopurpurin  4B 
2  per  cent  Chicago  Blue  4R 


Enter  at  140°  F.,  and  gradually  raise  to  the  boil,  and  continue  at  that  temperature 
for  one-half  hour.  Wash  well,  and  dry.  Chicago  Blue  will  perhaps  give  a  slightly 
redder  color  on  the  silk  than  on  the  cotton. 

In  dyeing  light  shades  a  bath  containing  only  glaubersalt  may  be  used;  but  for 
medium  and  heavy  shades  it  is  best  to  use  the  soap  and  a  little  soda  ash. 

This  one-bath  method  for  dyeing  the  two  fibers  alike  is  a  very  popular  one  and  is 
largely  used.  As  the  number  of  substantive  dyes  which  will  dye  the  cotton  and  the 
silk  exactly  the  same  shade  in  the  one  bath  is  rather  limited,  a  modification  of  this 

*  Ribbon  material  undyed  and  consisting  of  cotton  warp  and  back  with  silk  filling 
and  face  may  be  conveniently  used  on  which  to  dye  the  tests.  Or  if  desired  a  mixed 
test  skein  of  5  grams  may  be  prepared  by  reeling  together  strands  of  cotton  and  silk 
yarns. 


568  DYEING   OF   FABRICS  CONTAINING   MIXED   FIBERS 

metliod  is  to  dye  the  cotton  to  the  shade  desired  and  somewhat  darker  than  the  silk, 
and  then  to  dye  the  latter  to  the  ri^ht  shade  in  a  fresh  bath  with  the  necessary  acid  or 
basic  dyes. 

It  is  said  that  the  brightness  of  the  silk  is  lessened  when  salt  is  used  in  the  dyebath, 
but  the  addition  of  the  salt  only  be  dispensed  with  in  can  the  case  of  light  shades.  The 
effect  of  the  salt  on  the  silk,  however,  may  be  lessened  if  not  entirely  remedied,  bj-  adding 
a  sufficient  quantitj'^  of  soaj)  and  by  not  boiling.  It  is  also  said  that  common  salt  has 
less  effect  on  the  luster  of  the  silk  than  glaubersalt. 

Instead  of  employing  soda  ash  in  the  bath,  sodium  phosphate  may  be  used  with  like 
effect. 

The  best  results,,  probably,  are  obtained  by  dyeing  just  below  the  boiling  temperature 
(about  195  to  200°  F.) 

When  standing  baths  arc  used,  only  one-third  the  original  amount  of  soap  and  one- 
fourth  of  the  soda  ash  or  salt  should  be  added  for  succeeding  lots. 

After  dyeing  and  washing,  in  order  to  produce  a  better  scroop  and  to  brighten  the 
silk,  the  goods  may  be  passed  through  a  bath  made  weakly  acid  with  acetic  or  tartaric 
acid  at  a  temperature  of  about  80°  F.  squeezed,  and  dried. 

Exp.  229.  Dyeing  the  Cotton  with  Substantive  Dyes  and  Leaving  the  Silk  Undyed. — 
Use  the  same  kind  of  dyebath  as  in  Exp  228,  but  employ  the  following  dyes: 

1  per  cent  Diamine  Fast  Yellow  A  2  per  cent  Erica 

2  per  cent  Benzo  Sky  Blue  2  per  cent  Mikado  Orange  GO 
6  per  cent  Diazo  Black  BH  1  per  cent  Zambesi  Black  BR 

Exp.  230.  Dyeing  the  Silk  with  Acid  Dyes  and  Leaving  the  Cotton  White. — Prepare 
a  bath  containing  300  cc.  of  water,  5  per  cent  of  acetic  acid,  together  with  the  following 
dyes;  enter  at  140°  F.,  gradually  raise  to  the  boil,  and  continue  at  that  temperature 
for  one-half  hour: 

2  per  cent  Acid  Magenta  2  per  cent  Acid  Violet 

2  per  cent  Naphthol  Yellow  2  per  cent  Patent  Blue 

2  per  cent  Orange  II 

Exp.  231.  Production  of  Two-color  Effects  on  Satin. — Prepare  a  dyebath  containing 
300  cc.  of  water,  1  per  cent  of  Chrysophenine,  1  jier  cent  of  Acid  Magenta,  and  4  per  cent 
of  acetic  acid.  Dye  at  the  boil  for  one-half  hour.  In  the  same  manner  dye  with  the 
following  combinations: 

1  per  cent  Chrysophenine  and  1  per  cent  Formyl  Violet. 

1  per  cent  Chrysophenine  and  1  ])er  cent  Patent  Blue. 

Exp.  232.  Production  of  Two-colored  Effects. — A  two-bath  process  may  be  carried 
out  as  follows:  (o)  Dye  three  samples  of  satin  with  2  per  cent  of  Diamine  Orange  B  as 
described  in  E.xp.  228;  rinse,  and  top  the  silk  in  a  fresh  bath  containing  2  per  cent  Acid 
Violet  and  4  per  cent  of  sulphuric  acid;  boil  for  one-half  hour  and  wash.  Top  the 
second  sample  in  the  same  manner  with  2  per  cent  Acid  Green,  and  the  third  sample 
with  .5  per  cent  Naphthol  Blue  Black.  (6)  T)yc  three  samples  of  satin  with  2  per  cent 
Diamine  Sky  Blue  as  described  in  Exp.  229,  so  that  the  cotton  alone  is  dyed;  then  top  the 
silk  in  a  fresh  bath  containing  4  per  cent  acetic  acid  and  1  per  cent  Thioflavine  T;  dye 
for  one-half  hour  at  120°  F.;  top  the  second  sample  in  the  same  manner  with  2  per  cent 
^Methyl  Violet,  and  the  third  sample  with  2  per  cent  Magenta. 

Exp.  233.  Production  of  Two-colored  Effects. — Dye  eight  samples  of  satin  in  a  bath 
containing  300  cc.  of  water,  10  grams  Sulphur  Black,  10  grams  sodium  sulphide,  10 
grams  dextrin,  1  gram  soda  ash,  and  10  grams  glaubersalt;  dye  for  one  hour  at  about 
100°  F.,  then  squeeze  and  rinse.     This  will  dye  the  cotton  a  bluish  black  and  leave  the 


EXPERIMENTAL   STUDIES 


569 


silk  almost  white.  Keep  sample  1  without  further  dyeing.  Dye  sample  2  in  a  fresh 
bath  with  2  per  cent  Formyl  Blue  B  and  4  per  cent  acetic  acid  at  the  boil  for  one  half 
hour.  Dye  sample  3  in  the  same  manner  with  2  per  cent  Brilliant  Cochineal  2R  d1 
sample  4  wi^h  1  per  cent  Acid  Yellow  and  1  per  cent  Acid  Green.     Dye  sample's  .i  h 

lith  2'nP  Tr  '■■.  "n'  ""^^^  '  "'^'  -  P'^^  -"*  A-d  Magenta  Dye  ampl  7 
^ith  2  per  cent  Cyanide  Green.     Dye  sample  8  with  2  per  cent  Formyl  Violet  S4B 


CHAPTER  XXIV 

APPLICATION  OF  DYES  TO  THE  MINOR  VEGETABLE  FIBERS: 
LINEN,  RAMIE,  HEMP,  JUTE,  AND  ARTIFICIAL  SILK 

1.  The  Minor  Vegetable  Fibers. — Besides  cotton,  there  are  several 
other  vegetable  fibers  used  in  the  construction  of  textiles,  and  these  are 
frequently  dyed.  As  the  basis  of  all  vegetable  fibers  is  cellulose  (including 
also  artificial  silk),  the  general  dyeing  properties  of  all  these  fibers  are  very 
similar  to  that  of  cotton,  and  the  dyestuffs  and  methods  of  dyeing  employed 
for  the  latter  fiber  are  also  appUcable  to  the  other  members  of  this  group. 
Differences  in  physical  structure  and  properties,  however,  usually  entail 
some  differences  in  the  methods  of  handling  and  treating  the  goods. 

Linen  ranks  next  to  cotton  in  importance  as  a  vegetable  fiber  for  fabric 
purposes.  This  fiber  has  been  used  from  time  immemorial  for  the  weaving 
of  a  great  variety  of  fabrics,  and  in  fact  it  has  onlj^  been  since  the  last  two 
centuries  that  cotton  has  displaced  it  and  taken  first  rank.  Ramie  (or 
China  Grass)  has  long  been  used  in  China  and  is  highly  prized  on  account 
of  its  great  durability  and  strength;  it  has  been  used  to  any  extent  only 
for  the  past  quarter  of  a  centuiy  in  Europe  and  America.  Hemp  is  a 
rather  indeterminate  name  apphed  to  fibers,  as  it  is  used  to  designate  quite 
a  wide  variety  of  vegetable  fibers  which  differ  considerably'  in  their  quality 
and  physical  properties.  The  kind  most  used  for  fabric  purposes  is  ItaUan 
hemp,  which  is  a  fine  fight-colored  fiber  that  can  be  satisfactorily  spun 
into  yarns  for  wea^'ing.  ^Manila  hemp  and  other  varieties  of  hemps  are 
rather  coarse  in  structure  and  are  used  chiefly  for  the  making  of  twine  and 
cordage,  and  consequently  are  seldom  dyed.  Jute  is  a  rather  coarse  fiber  of 
a  dark  brown  natural  color,  gi'own  principally  in  India;  its  chief  use  is  for 
making  gunny  sacks  and  bagging,  for  which  purpose,  of  course,  it  is  not 
dyed.  It  is  also  used,  however,  to  a  considerable  extent  for  making  fabrics 
for  wall  covering,  upholstery,  and  draperies.  Jute  yarns  are  also  used 
largety  as  a  backing  for  carpets  and  rugs.  When  used  for  such  purposes, 
they  are  largely  dyed.  Artificial  silk  is  also  considered  in  this  connection, 
for  though  it  is  an  artificial  fiber,  it  consists  of  cellulose,  and  hence  comes 
under  the  same  general  class  as  the  other  vegetable  fibers. 

570 


DYEING  OF   LINEN 


571 


2.  The  Dyeing  of  Linen. — Linen  is  distinguished  from  cotton  chiefly 
in  its  physical  appearance  and  properties.  Cotton  is  a  seed-hair  and 
consists  of  a  single  elongated  cell,  varying  from  about  h  to  2  ins.  in 
length.  Linen,  on  the  other  hand,  is  a  bast  fiber;  that  is,  it  is  obtained 
from  the  stalk  of  the  flax  plant.  The  conmiercial  fiber  may  reach  several 
feet  in  length,  and  consists  of  a  bundle  of  smaller  fiber  cells.  As  obtained 
from  the  plant,  linen  has  a  grayish  or  brownish  color  and  contains  a  con- 
siderable amount  of  vegetable  gums  and  impurities.  It  is  also  a  harder 
fiber  than  cotton,  having  thicker  cell  walls,  and  consequently  is  not  as 


Fig.  273.— Gas  Singeing  Machine.     (Curtis  &  Marble). 


easily  penetrated  by  solutions  of  dyestuffs  and  mordants.  It  is  also  harder 
to  bleach  on  account  of  the  high  color  and  many  impurities  present  in  the 
raw  fiber.  Furthermore,  since  the  commercial  long  fiber  consists  of  a 
number  of  small  cells  cemented  together,  severe  treatment  with  strong 
chemical  agents  (such  as  chloride  of  lime)  is  liable  to  cause  damage  to  the 
material,  therefore  the  bleaching  must  be  conducted  more  carefully  even 
than  with  cotton. 

Linen  may  come  to  the  dyer  either  in  the  form  of  yarn  or  of  the  woven 
fabric.     In  either  case,  it  will  usually  be  necessary  to  boil  out  the  goods 


572     APPLICATION   OF   DYES   TO   THE   MINOR   VEGETABLE   FIBERS 

w4th  alkaline  solutions  in  order  to  remove  most  of  the  material  impurities. 
In  the  event  of  dyenig  Ught  shades  it  will  also  be  necessary  to  bleach  the 
goods  before  dyeing.* 

The  action  of  chemicals  on  linen  is  practically'  the  same  as  on  cotton; 
it  being  somewhat  more  resistant  to  acids  and  slightly  more  affected  by 
alkaUes;  it  is  also  more  affected  by  the  usual  bleaching  agents  than  cotton. 
It  is  quite  inert  towards  solutions  of  metallic  salts  and  consequently  the 
application  of  metallic  mordants  presents  the  same  difficulties  as  with 
cotton.  It  absorbs  tannic  acid,  however,  and  consequently  can  be  mor- 
danted with  tannin  and  antimony  in  the  same  manner  as  cotton. 

With  dyestuffs,  Unen  readily  combines  with  the  substantive  colors;  it 
may  be  dyed  with  the  basic  colors  if  previously  mordanted  with  tannin. 
Towards  the  acid  and  mordant  dyes,  it  is  inert;  with  the  sulphur  and  vat 
dj'es  it  combines  in  the  same  manner  as  cotton. 

Before  dyeing  the  raw  linen  fiber  it  is  necessary  to  remove  most  of  the 
incrusting  impurities.  This  is  done  by  boiling  the  goods  in  a  bath  con- 
taining 5  per  cent  of  soda  ash;  this  is  usually  done  in  open  tubs  and  not  in 
pressure  kiers,  as  boiling  with  alkali  imder  pressure  is  liable  to  weaken  the 
fiber.  To  obtain  a  well-purified  fi]>cr,  it  is  usually  necessary  to  repeat  the 
alkali  boiling  three  times  with  intermediate  rinses.  The  first  treatment 
with  alkali  causes  the  raw  linen  to  become  darker  in  color;  the  alkali 
bath  also  becomes  dark  colored  and  foul.  After  the  third  alkali  lx)il  the 
fiber  is  of  a  light  brownish  yellow  color.  The  amount  of  impurities  in 
raw  Hnen  is  about  15  to  30  per  cent,  varying  with  the  quality  of  the  fiber 
and  the  nature  of  the  retting  process.  After  complete  boiling  out  there  still 
remains  about  7  per  cent  of  impurities  in  the  linen,  which  can  only  be 
removed  by  bleaching,  f 

The  principal  dyes  used  at  the  present  time  for  linen  are  the  substantive 
colors,  and  to  a  lesser  extent  the  sulphur  and  basic  eyes.  Linen  is  some- 
what harder  to  dye  than  cotton,  it  being  more  difficult  to  obtain  well- 
penetrated  colors,  therefore  the  dyebath  is  generally  used  at  a  higher 
temperature,  it  usually  l_>eing  necessarj'  to  boil  the  goods  vigorously  in  the 
dyebath.     Also  it  is  necessary  to  use  more  concentrated  dye  liquors. 

*  Linen  goods  include  a  wide  variety  of  fabrics  such  as  hea\y  sail-cloth  and  drills, 
sheetings,  toweling,  dre.ss  goods,  batistes,  shirtings,  damask,  hangings  and  draperies, 
upholstery  fabrics,  buckram,  bookbinders'  cloth,  etc.  Owing  to  the  relatively  high  cost 
of  linen  during  late  years,  cotton  is  being  used  more  and  more  to  replace  it,  cotton 
yams  being  spun  and  finished  in  such  a  way  as  to  closely  imitate  the  characteristic 
appearance  of  linen,  and  many  staple  fabrics  which,  in  former  j'ears,  were  made  exclu- 
sively of  linen  are  now  made  from  cotton. 

t  According  to  Schott's  process  for  boilintvout  raw  linen  yarn,  the  goods  are  boiled 
in  a  weak  solution  of  sodium  bisulphite,  it  being  claimed  that  the  impurities  in  the 
fiber  are  converted  by  the  sulphurous  acid  into  soluble  compounds;  the  yarn  is  then 
thoroughly  washed,  treated  with  a  weak  hj-pochlorite  bath  and  then  weU  washed  again. 


DYEING   LINEN 


573 


The  following  processes  are  of  interest  in  the  dyeing  of  Unen : 

(1)  Prepare  the  dyebath  with  10  to  20  per  cent  of  common  salt  and 
the  necessary  amount  of  well-dissolved  substantive  dyes,  and  dye  for  one 
hour  at  a  boiling  temperature. 

(2)  "When  it  is  particularly  difficult  to  obtain  good  penetration  of  the 
color,  prepare  the  dyebath  with  3  to  5  per  cent  of  soap  and  1  to  2  per  cent  of 


Fig.  274.— Jute  Calender. 


soda  ash ;  dye  at  the  boil  for  one-half  hour  and  then  add  5  to  20  per  cent  of 
glaubersalt.     An  addition  of  Turkey-red  oil  is  also  of  advantage. 

(3)  To  dye  with  basic  colors,  first  mordant  with  2  to  4  per  cent  of  tan- 
nic acid  (or  a  corresponding  amount  of  sumac  extract) ;  boil  for  one  hour 
and  steep  in  the  cooling  bath  overnight.  Squeeze  and  fix  in  a  fresh  bath 
containing  1  to  2  per  cent  of  tartar  emetic;  run  at  140°  F.  for  one  hour. 
Wash,  and  dye  in  a  bath  containing  the  well-dissolved  basic  dye  and  4 
per  cent  of  alum;  enter  the  goods  cold  and  slowly  raise  the  temperature 


574     APPLICATION   OF   DYES   TO   THE   MINOR   VEGETABLE   FIBERS 

to  180  to  190°  F.  Care  must  be  taken  in  dyeing  the  basic  colors  to  obtain 
even  and  well-penetrated  shades.  The  basic  dyes  may  also  be  used  for 
topping  linen  dyed  with  the  substantive  colors.* 

(4)  The  sulphur  dyes  are  used  on  linen  in  the  same  manner  as  for 
cotton,  though  usually  the  quantity  of  salt  added  to  the  bath  must  he 
decreased  and  the  amount  of  sodium  sulphide  somewhat  increased  in  order 
to  obtain  well-penetrated  and  level  colors.  It  is  also  beneficial  to  add 
some  Turkey-red  oil  to  the  bath.  The  sulphur  dyes  are  now  used  quite 
largely  for  the  dyeing  of  blue,  black,  and  brown  on  linen  yarns  and  piece- 
goods.  The  sulphur  dyes  on  linen  may  also  be  topped  with  basic  dyes  in 
a  fresh  cold  bath  with  the  addition  of  acetic  acid  or  alum.  Considerably 
less  sulphur  dye  is  also  necessary  in  dyeing  linen  as  compared  with  cotton 
to  produce  the  same  shade. 

(5)  Indigo  is  largely  used  for  dyeing  fast  blue  on  linen,  and  the  other 
vat  dyes  are  also  used  where  colors  of  great  fastness  to  light,  washing,  and 
even  bleaching  (for  towel  headings,  etc.)  is  desired.  At  the  present  time 
the  hj-posulphite  vat  is  principally  used,  and  is  prepared  and  employed  in 
the  same  manner  as  for  cotton.  It  must  always  be  borne  in  mind,  how- 
ever, that  linen  is  harder  to  penetrate,  and  especial  care  must  be  exercised 
on  this  account. 

(6)  The  alizarine  and  chrome  mordant  dyes  are  not  adapted  for  the 
dyeing  of  linen,  but  these  colors  are  extensively  used  in  the  printing  of 
linen  piece-goods. 

After  dyeing  linen  yarn  is  usually  lustered  by  treatment  in  a  yarn  man- 
gle or  cylinder.     Linen  cloth  is  lustered  by  treatment  on  a  calender  machine. 

At  the  present  time,  there  are  manj^  fabrics  made  up  of  half  linen; 
that  is  to  say,  part  linen  and  part  cotton.  In  dyeing  such  goods,  the  same 
methods  are  employed  as  for  cotton,  the  substantive  or  sulphur  dyes  being 
principally  used.  Owing  to  the  harder  nature  of  the  linen  fiber  and  its 
resistance  to  the  penetration  of  the  color,  great  care  must  be  exercised  in 
order  to  obtain  uniform  shades  on  both  the  fibers.  It  is  recommended 
to  use  some  Turkey-red  oil  in  the  dyebath. 

Fabrics  are  also  woven  of  part  linen  and  part  wool  (usually  a  linen  warp 
and  a  wool  filling),  and  these  dyed  in  the  same  manner  as  union  goods  of 
cotton  and  wool. 

The  apparatus  used  in  linen  dyeing  is  comparatively  simple.  Skein 
yarn  is  generally  dyed  by  hand  on  sticks  hung  in  long  rectangular  tubs. 
These  tubs  usually  have  to  be  deeper  than  those  used  for  cotton,  as  the 
linen   hanks  are   woimd  longer.     Skein   dyeing  machines  may  also   be 

*  The  basic  colors  chiefly  employed  for  dyeing  linen  are : 

Rhodamine  B  and  G  Brilliant  Green 

Safranine  Methylene  Blue 

.\uramine 


D\nEING  RAMIE  AND  JUTE  575 

employed  with  good  results.  Linen  cloth  is  generally  dyed  in  the  jigger 
or  in  an  open-width  dyeing  machine  rather  than  on  a  winch  machine  in 
rope  form. 

3.  The  Dyeing  of  Ramie. — This  material  is  also  a  bast  fiber.  It  is 
long,  quite  white  in  color  and  lustrous  in  appearance.  It  is  rather  smooth 
and  therefore  does  not  lend  itself  very  well  to  spinning  like  cotton,  and 
where  used  in  this  country  for  fine  yarns  it  is  usually  mixed  with  some 
other  fiber  such  as  cotton  or  wool.  Ramie  as  obtained  from  the  plant 
contains  a  large  amount  of  vegetable  gums,  but  in  order  to  bring  it  into  a 
condition  proper  for  spinning  these  impurities  have  to  be  removed,  so 
that  when  the  dyer  gets  ramie  yarns  or  fabrics  for  dyeing  no  previous  scour- 
ing operation  is  necessary.  Furthermore,  the  fiber  is  so  white  in  color  that 
it  does  not  have  to  be  bleached  except  when  dyeing  very  bright  and  del- 
icate shades.  The  dyeing  and  bleaching  of  ramie  materials  is  carried  out 
precisely  as  in  the  case  of  cotton,  the  same  dyes  and  processes  being 
employed.  As  the  fiber  is  considerably  harder  and  thicker  than  cotton, 
due  allowance  must  be  made  in  order  to  procure  even  and  well-peneti'ated 
colors. 

Ramie  is  also  known  as  China  Grass,  Nettle  Fiber  or  Rhea  Fiber.  In 
this  country  it  is  seldom  used  by  itself  for  the  making  of  fabrics,  being  mostly 
employed  for  effect  threads  or  patterns  in  wool  goods.  There  are  some 
decorative  and  upholstery  fabrics,  however,  made  from  ramie  alone,  but 
these  are  rather  scarce. 

4.  The  Dyeing  of  Jute. — Jute  is  also  a  bast  fiber  of  rather  coarse 
character  and  dark  color.  By  proper  methods  of  decortication  and  treat- 
ment, however,  it  is  possible  to  obtain  a  jute  fiber  which  is  quite  fine  and  of 
good  appearance,  and  which  makes  a  yarn  and  fabric  of  pleasing  appear- 
ance. Jute  is  chiefly  used  by  itself  for  making  rather  coarse  fabrics  for 
draperies,  upholstery  goods,  wall-coverings,  and  as  a  base  for  carpets  and 
rugs.  Jute  differs  somewhat  from  the  preceding  vegetable  fibers  and  cot- 
ton in  that  it  is  rather  strongly  lignified,  and  therefore  instead  of  consisting 
of  practically  pure  cellulose,  it  contains  compounds  bearing  a  close  resem- 
blance to  the  vegetable  tannins.  On  this  account  jute  may  be  dyed 
directly  with  the  basic  dyes  as  well  as  the  substantive  and  sulphur  dyes. 
Also  the  acid  dyes  are  taken  up  by  jute  far  better  than  by  the  other  vege- 
table fibers,  and  these  dyes  are  useful  for  the  dyeing  of  this  fiber. 

On  account  of  the  rather  dark-brown  color  of  jute  it  is  necessary  to 
bleach  it  before  dyeing  unless  dark  heavy  shades  are  desired.  The  cleaning 
and  bleaching  of  jute  may  be  carried  out  in  the  following  manner :  Steep 
the  material  overnight  in  lukewarm  water  in  order  to  soften  up  the  fiber 
and  the  hard  impurities;  rinse  and  boil  for  one-half  hour  with  a  solution 
containing  ^  oz.  soda  ash  and  ^  oz.  sodium  silicate  per  gallon.  This  will 
remove  most  of  the  glutinous  and  greasy  matters;    rinse  well,  and  then 


576     APPLICATION   OF   DYES   TO   THE   MINOR   VEGETABLE   FIBERS 

bleach  in  a  bath  containing  a  solution  of  sodium  hypochlorite  at  1°  Tw., 
cold,  for  ten  hours.  A  solution  of  chloride  of  liine  may  also  be  used. 
Rinse  well  and  sour  with  sulphuric  acid  at  1°  Tw.,  after  which  rinse  well 
again  and  dye.  A  somewhat  clearer  white  may  be  obtained  when  desired 
by  blea(;hing  with  permanganate  of  potash  and  sodium  bisulphite  in  addi- 
tion to  the  treatment  with  the  hypochlorite.  Care  must  be  taken  in  the 
bleaching  not  to  injure  the  fiber.  After  bleaching  it  is  advisable  to  soap 
the  goods  both  for  the  purpose  of  neutralizing  any  residues  of  acid  and 
also  to  soften  the  fiber  and  give  it  a  desirable  luster. 

The  acid  dyes  are  much  used  for  the  dyeing  of  jute,  as  they  give  colors 
with  good  penetration  and  of  good  fastness  to  light.  To  dye  with  the  acid 
colors  prepare  the  bath  with  2  to  5  per  cent  of  alum  and  dye  for  one  hour 
at  the  boil,  then  allow  to  cool  down  in  the  bath  for  another  half  hour.  The 
colors  so  obtained  have  not  much  fastness  to  washing,  but  this  character 
of  fastness  is  seldom  necessary  on  fabrics  made  from  jute.  In  dyeing  jute 
it  must  be  borne  in  mind  that  the  fiber  has  a  great  affinity  for  lime  com- 
pounds, consequently  the  water  used  in  the  dyebath  should  be  as  free  from 
lime  as  possible,  and  if  only  hard  water  is  available  for  use  this  should  be 
corrected  by  the  addition  of  acetic  acid  in  sufficient  quantity.* 

The  basic  dyes,  as  already  mentioned,  dye  jute  directly  without  the 
necessity  of  a  previous  mordanting  with  tannin.  The  dyebath  f  is  pre- 
pared with  the  well-dissolved  color  solution  and  |  to  2  per  cent  of  almn  is 
added;  the  dyeing  is  started  cold  or  lukewarm  and  the  temperature  is 
gradually  raised  to  180°  F.  In  cases  where  the  dye  shows  a  tendency  to 
uneven  shades  it  is  best  to  add  the  color  solution  to  the  bath  in  several 
portions.  In  dyeing  bright  red  shades  it  is  recommended  to  add  to  the 
bath  1  to  2  per  cent  of  oxalic  acid.  J 

The  substantive  colors  on  jute  are  usually  dyed  in  a  bath  containing 
10  to  20  per  cent  of  glaubersalt  or  common  salt,  the  former  being  preferred.! 

*  For  the  production  of  particularly  bright  i)ink  colors  on  jute  it  is  necessary  to  use 
Eosin  or  Rhodamine  on  bleatihed  material.  Eosin  is  dyed  in  a  concentrated  bath 
with  the  addition  of  25  to  50  per  cent  of  common  salt,  starting  lukewarm  and  slowly 
bringing  to  the  boil;  then  shut  off  the  heat  and  dye  for  a  further  one-half  hour.  The 
pink  obtained  with  Eosin,  though  brilliant,  is  not  fast  to  light.  Rhodamine  gives  a 
bright  pink  of  good  fastness  to  light.  It  is  dyed  with  the  addition  of  acetic  acid.  If 
necessary  it  may  be  shaded  with  Auramine. 

t  Hard  water  should  be  corrected  by  the  addition  of  acetic  acid.  For  moderate 
hardness  (5  to  7°),  for  instance,  use  one-half  gallon  of  acetic  acid  (9°  Tw.)  to  100  gallons 
of  water. 

t  Colors  on  jute  which  are  faster  to  cro(;kiiig  and  water  may  be  obtained  with  the 
basic  dyes  by  giving  an  after-treatment  in  a  lukewarm  bath  containing  1  per  cent  of 
tannic  acid. 

§  When  dyeing  heavy  shades  with  the  substantive  colors  the  jute  should  be 
left  in  the  cooling  bath  for  some  time  in  order  that  it  may  take  up  the  maximum  amount 
of  color. 


DYEING   COIR 


577 


The  colors  obtained  have  good  fastness  to  water  and  crocking;  the  dye 
penetrates  well  and  the  fiber  is  left  with  a  good  soft  handle.  Basic  dyes 
may  be  used  for  topping  the  substantive  colors  for  the  purpose  of  obtaining 
brighter  shades. 

The  sulphur  dyes  are  not  so  well  adapted  for  the  dyeing  of  jute,  as  the 
strongly  alkaline  baths  tend  to  weaken  the  fiber.  However,  for  certain 
purposes,  especially  for  black,  the  sulphur  dyes  may  be  used  with  sodium 
sulphide  but  without  the  addition  of  soda  ash,  as  is  customary  with  the 


Fig.  275.— Picking  and  Shearing  Machine  for  Silk  Goods.     (Curtis  &  Marble). 


dyeing  of  cotton.     Also  the  temperature  of  the  bath  should  be  kept  below 
the  boiling  point.* 

5.  Dyeing  of  Coir  Fiber.— This  fiber  is  obtained  from  the  husk  of  the 
cocoanut  and  is  a  coarse  brown-colored  fiber.  It  is  used  somewhat  for 
mattings  and  rugs  and  is  sometimes  required  to  be  dyed.  The  character 
of  the  fiber  is  very  similar  to  that  of  jute  and  it  may  be  dyed  in  practically 
the  same  manner  with  the  acid,  basic,  and  substantive  dyes.f 

*  It  is  best  not  to  run  the  dyebath  at  a  temperature  over  130°  F. 

t  Coir  may  be  dyed  either  raw  or  bleached.  The  bleaching  may  be  done  in  the  same 
manner  as  for  jute  with  the  use  of  bleaching  powder,  potassium  permanganate,  etc.  Or 
it  may  be  bleached  with  the  use  of  hydrosulphite  products  such  as  Decroline,  according 


578     APPLICATION   OF   D\'ES   TO   THE   MINOR   VEGETABLE   FIBERS 

6.  Dyeing  of  Hemp. — This  fiber  when  used  for  textile  purposes  is 
rather  soft  and  fine  in  structure  and  of  a  liglit-brown  color;  it  also  pos- 
sesses a  good  luster,  and  closely  resembles  linen.  It  is  also  closely  related 
to  this  fiber  in  its  dyeing  properties.  It  is  chiefly  dyed  with  the  sub- 
stantive colors,  though  for  bright  shades  the  basic  dyes  are  used  on  a  mor- 
dant of  tannin  and  antunony.* 

7.  DyeLfig  of  Artificial  Silk. — This  is  a  cellulose  fiber  with  properties 
closely  resembling  the  other  vegetable  fibers  and  is  prepared  b}-  forcing 
thick  solutions  of  cellulose  through  verj^  fine  orifices  or  spinnerets.  There 
are  three  varieties  of  artificial  silk:  (a)  Chardonnet  or  Collodion  Silk, 
made  from  a  solution  of  nitrated  cotton  in  a  mixture  of  alcohol  and  ether; 
the  fiter  so  obtained  consists  of  a  fine  filament  of  nitrated  cellulose  which  is 
denitrated  by  treatment  with  a  solution  of  anmionium  sulphide  or  other 
suitable  denitratmg  agent,  so  that  the  final  commercial  fil :er  is  cellulose. 

(6)  Cuprammonium  Silk,  also  known  as  Glanzstoff,  prepared  from  a 
solution  of  cotton  in  ammoniacal  copper  oxide.  After  spinning  the  fila- 
ment is  treated  with  a  weak  acid  solution  that  dissolves  out  the  copper, 
leaving  a  fiber  of  pure  cellulose. 

(c)  Viscose  Silk  is  prepared  from  a  compound  known  as  viscose,  which 
is  obtained  by  treating  cotton  or  purified  wood-pulp  with  strong  caustic 
soda  and  carbon  cUsulphide.  The  filaments,  after  spinning,  are  treated 
so  as  to  remove  the  sulphur  compounds  and  salts,  leaving  pure  cellulose 
as  the  fiber,  t 

to  the  following  method  (Badische).     Steep  the  coir  overnight  in  a  ba^h  containing 
2  pints  hydrochloric  acid  (30  per  cent), 
I5  lbs.  Decroline, 
70  gallons  water, 
then  rinse  well  in  fresh  water.     The  bleaching  bath  is  not  exhausted  and  may  be  fresh- 
ened up  for  use  with  further  lots  by  adding  14  gallons  water,  h  pint  hydrochloric  acid 
and  6  ozs.  Decroline.     Sulphuric  acid  (3  ozs.  per  10  gallons)  may  be  used  in  place  of 
hydrochloric  acid. 

In  dyeing  coir  with  the  acid  dyes  it  is  well  to  allow  the  material  to  cool  down  in  bath 
in  order  to  better  absorb  the  color. 

*  Colors  for  hemp  twines  are  sometimes  required  that  will  not  mark  off  on  to  white. 
The  following  dyes  are  suitable  for  these  colors: 
(a)  Acid  dyes: 

Pure  Blue  Cotton  Scarlet 

Orange  X  Eosin 

Erythrine  P 
(6)  Basic  dyes: 

Auramine  Methylene  Blue 

Rhodamine  B,  G,  6G  Diamond  Green  G,  B 

Safranine  Magenta 

Methyl  Violet  Victoria  Blue 

Jute  Black 
(c)   Substantive  dyes:  almost  all  of  this  class, 
t  Besides  the  three  varieties  of  artificial  fiber  there  are  other  forms  in  which  this 


DYEING   ARTIFICIAL  SILK  579 

Viscose  silk  is  manufactured  on  a  very  large  scale  in  this  country  and  is 
gradually  supplanting  the  other  varieties  also  in  Europe.  Artificial  silk, 
by  whatever  method  prepared,  consists  of  practically  pure  cellulose,  or 
rather  a  hydrated  cellulose.  The  filaments  are  very  fine  and  of  great 
length,  being  drawn  out  in  practically  a  continuous  fiber  in  the  same  man- 
ner as  real  silk.  It  has  a  high  degree  of  luster,  surpassing  in  this  respect 
even  real  silk  itself.  It  does  not,  however,  have  the  strength  or  elasticity 
of  real  silk,  and  when  wetted  with  water  it  becomes  seriously  weakened 
and  softened,  while  treatment  with  alkalies,  especially  in  hot  solutions, 
causes  the  fiber  to  disintegrate  owing  to  the  solvent  action  of  the  alkali. 
On  this  account  great  care  must  be  exercised  in  dyeing  and  bleaching  arti- 
ficial silk  to  avoid  any  undue  handling  when  the  fiber  is  wet  and  also  the 
solutions  employed  must  be  as  cold  as  possible,  and  the  use  of  strong 
alkalies  must  always  be  avoided.  Fortunately,  however,  artificial  silk 
is  very  absorptive,  and  takes  up  dyestuffs  very  readily  from  solutions  with- 
out the  need  of  much  heating  of  the  bath,  so  that  most  of  the  dyeing  is 
done  cold  or  at  a  lukewarm  temperature.  The  bleaching  of  artificial  silk 
is  usually  done  in  the  process  of  manufacture,  but  sometimes  the  fiber 
comes  to  the  dyer  in  the  raw  state,  having  a  slight  yellowish  brown  color, 
and  the  dyer  is  required  to  bleach  it  either  for  the  purpose  of  white  goods 
or  for  dyeing  bright  and  delicate  shades.  In  this  case  the  bleaching  is 
done  with  a  weak  solution  of  chloride  of  lime  in  practically  the  same  man- 
ner as  with  cotton,  after  which  the  goods  are  soured  with  a  bath  of  weak 
acid  and  then  soaped  in  a  lukewarm  solution. 

The  dyes  principally  employed  for  artificial  silk  are  the  substantive 
colors.  These  are  dyed  for  one  hour  at  120  to  140°  F.  in  a  short  bath  with 
the  addition  of  5  to  20  per  cent  of  glaubersalt.  When  dyeing  light  shades 
it  is  recommended  to  use  10  per  cent  of  glaubersalt  and  5  per  cent  of  soap.* 
As  the  fiber  takes  up  the  color  very  rapidly  care  must  be  used  in  obtaining 
even  and  level  dyeings. f  Sometimes  lack  of  uniformity  is  caused  by 
uneven  density  in  the  fiber  itself,  due  to  imperfections  in  the  spinning,  and 
this  is  very  hard  (and  sometimes  impossible)  for  the  dyer  to  overcome. 

Owing  to  the  great  absorptive  power  of  artificial  silk  it  may  also  be 
dyed  directly  with  most  of  the  basic  dyes  t  and  some  of  the  acid  dyes, 

material  is  sometimes  met,  such  as  Viscolline  yarn,  which  is  a  cotton  yarn  coated  with 
artificial  (viscose)  silk;  also  artificial  horse-hair,  which  is  a  very  coarse  variety  of  arti- 
ficial silk. 

*  When  dyeing  with  Chrysamine  5  per  cent  of  sodium  phosphate  must  also  be  added. 

t  Soluble  oil  (Monopol  Oil)  is  frequently  added  to  the  dyebaths  for  artificial  silk  in 
order  to  promote  level  dyeings  and  also  to  give  the  fiber  a  softer  handle. 

X  The  Chardonnet  silk  possesses  a  greater  affinity  for  the  basic  dyes  than  the  other 
forms  of  artificial  silk,  probably  due  to  slight  residue  of  nitrogenous  matter  in  the  fiber. 
On  the  other  hand,  it  has  a  lesser  affinity  for  the  substantive  dyes.  The  cuprammonium 
silk  has  great  aflSnity  for  the  substantive  and  but  little  for  the  basic  dyes.  The  viscose 
silk  stands  midway  between  the  other  two. 


580 


APPLICATION   OF   DYES   TO   THE   MINOR   VEGETABLE   FIBERS 


though  the  latter  do  not  yield  colors  that  are  fast  to  washing.*  In  dyeing 
with  the  basic  dyes,  the  artificial  silk  is  first  wet  out  in  water  at  100°  F. 
and  then  dyed  for  one  hour  in  a  neutral  bath  f  at  85°  F.,  or  not  higher 
than  100°  F.  The  basic  dj-e  should  be  very  carefully  dissolved  and  filtered 
and  the  solution  is  added  to  the  bath  m  several  lots  in  order  to  obtain  level 
colors.  Also  if  hard  water  is  used  in  the  dyebath  it  should  be  corrected  by 
the  addition  of  acetic  acid.  When  dyeing  in  hand-tubs  the  skeins  should  be 
hung  on  glass  or  enameled  sticks  and  turned  with  gi-eat  care  to  prevent 


Fig.  276. — Machine  for  Polishing  and  Sanding  Worsteds.     (Parks  &  Woolson.) 


breakage  of  the  silk.  After  dyeing  the  goods  are  rinsed  but  not  WTung  out 
as  this  would  injure  the  fiber.  The  excess  of  water  should  be  removed 
by  a  hydro-extractor.  "UTien  the  silk  is  dry  the  skeins  are  given  a  glossing 
by  slight  stretching,  as  in  the  case  of  real  silk.  A  scroop  may  also  be  given 
by  treating  with  a  bath  of  weak  acetic  or  tartaric  acid  and  drjing  without 
rinsing. 

*  The  phthalein  dyes  (Eosin,  Erythrosine  and  Rose  Bengale)  may  be  dyed  on  arti- 
ficial silk  by  using  a  short  bath  at  100°  F.  with  the  addition  of  2  lbs.  common  salt  per 
10  gallons  of  liquor.  The  goods  are  whizzed  and  dried  without  rinsing.  Methyl  Blue 
and  Water  Blue  may  be  dyed  at  100°  F.  with  the  addition  of  10  per  cent  of  alum. 

t  To  obtain  a  more  level  dyeing  2  to  5  per  cent  acetic  acid  may  be  added  to  the  bath. 


DYEING   ARTIFICIAL  SILK  581 

To  obtain  heavier  shades  with  the  basic  dyes  and  also  when  fast  colors 
are  desired,  the  goods  should  be  first  mordanted  with  tannin  and  tartar 
emetic  in  the  same  manner  as  with  cotton.  Steep  the  goods  in  a  bath 
containing  2  to  5  per  cent  of  tannic  acid  and  1  per  cent  of  hydrochloric 
acid  at  120°  F.  for  several  hours;  then  hydro-extract  and  fix  in  a  fresh  bath 
with  1  to  2  per  cent  of  tartar  emetic.  Dye  with  the  addition  of  2  to  3  per 
cent  of  acetic  acid  and  at  a  temperature  of  85  to  100°  F.*  The  basic 
colors  may  also  be  used  for  brightening  the  shades  obtained  with  the 
substantive  dyes  by  topping  in  a  fresh  cold  bath  with  the  addition  of  a 
small  quantity  of  acetic  acid. 

The  sulphur  colors  may  also  be  used  to  some  extent  in  the  dyeing 
of  artificial  silk,  preparing  the  dyebath  with  the  same  quantity  of  sodium 
sulphide  as  dyestuff,  5  to  25  per  cent  of  glaubersalt  and  1  to  4  per  cent  of 
soda  ash;  dye  for  one  hour  at  100  to  120°  F.f 

Artificial  silk  is  very  extensively  used  at  the  present  time  for  hosiery, 
generally  in  connection  with  cotton  feet  and  tops;  also  the  artificial  silk 
is  frequently  spliced  with  a  thread  of  real  silk  and  knitted  together.  Arti- 
ficial silk  is  also  used  largely  for  silk-effect  threads  in  shirtings  and  blouse 
material  and  in  pattern  effects  in  connection  with  cotton,  mercerized  cotton, 
or  real  silk  in  the  weaving  of  various  dress  goods,  necktie  material  and  fancy 
fabrics  for  passementerie  and  trimmings,  braids,  upholstery  goods,  draper- 
ies, etc.  When  dyeing  in  the  piece  together  with  other  fibers  great  care 
and  ingenuity  are  required  to  obtain  uniforjn  colors  on  both  fibers.  Usually 
it  is  necessary  to  dye  the  material  in  the  yarn  before  weaving  in  order  to 
obtain  the  effects  desired. 

Good  deep  blacks  on  artificial  silk  are  usually  dyed  with  the  developed 
colors,  first  dyeing  with  a  Diazo  Black,  then  diazotizing  with  sodimn  nitrite 
and  hydrochloric  acid  and  finally  developing  with  beta-naphthol  or  phenyl- 
ene-diamine.  The  process  is  carried  out  in  the  same  manner  as  with  cot- 
ton. After  dyeing  the  fiber  is  generally  brightened  by  treatment  hi  an 
emulsion  of  glue,  oil,  and  acetic  acid,  as  this  increases  the  luster  and 
improves  the  handle  of  the  goods.  % 

*  To  obtain  dyeings  fast  to  acids  for  effect  threads  to  be  used  in  woolen  goods,  the 
dyed  silk  should  be  again  run  through  the  old  mordanting  baths  of  tannin  and  tartar 
emetic,  recharging  the  baths  with  about  two-thirds  of  the  original  quantities. 

t  After  dyeing  the  cuprammonium  or  viscose  silks  with  the  sulphur  colors  the  goods 
should  be  soaped  lukewarm,  rinsed,  and  then  soured  in  a  weak  acetic  acid  bath.  In 
the  case  of  Chardonnet  silk  the  soaping  should  be  omitted  and  only  the  acid  bath  used. 
This  is  for  the  purpose  of  removing  all  of  the  alkali,  which  would  otherwise  cause  a 
rotting  of  the  fiber.  In  dyeing  with  Sulphur  Blacks  it  is  recommended  by  some  to 
after-treat  in  a  bath  containing  1  lb.  of  sodium  acetate  or  formate  to  10  gallons.  Also 
in  the  dyebath  it  is  of  advantage  to  add  some  soluble  oil. 

I  Brown  shades  of  good  fastness  to  washing  and  cross-dyeing  (for  effect  threads) 
may  be  obtained  by  the  use  of  Primuline  and  a  Diazo  Black  diazotized  and  developed 
with  resorcine  or  phenylene-diamine.  The  brown  shades  obtained  with  the  sulphur 
colors  are  also  very  fast  to  light. 


CHAPTER  XXV 
THEORY  OF  DYEING 

I.  General  Theory  of  Dyeing. — There  have  been  throe  main  theories 
to  explain  the  general  process  of  dyeing.  The  chemical  theory  supposes 
that  dyeing  involves  a  chemical  reaction  between  the  fil:)er  and  the  dye- 
stuff  and  that  a  definite  chemical  compound  known  as  the  color-lake  is 
thus  produced.  The  mechanical  theory,  on  the  other  hand,  considers  the 
effect  of  dyeing  to  be  simply  a  deposit  of  colored  particles  in  the  substance 
of  the  filler  *  and  the  combination  so  formed  to  be  merelj^  a  mechanical 
mixture.  The  solid  solution  theory  advocates  the  view  that  the  coloring 
of  the  fiber  in  dyeing  is  due  to  the  fact  that  the  substance  of  the  fiber 
(or  any  other  body  w^hich  may  be  so  dyed)  dissolves  the  coloring  matter  or 
color-lake  much  in  the  same  maimer  that  molten  glass,  for  example,  dis- 
solves various  pigments  and  becomes  colored  thereby. 

The  chemical  theory  is  supported  b}'  the  facts  that  the  animal  fibers 
(wool  and  silk)  exhibit  well-defined  chemical  reactivities  of  an  acid  and  a 
basic  character,  and  that  these  fibers  reacUly  dye  with  the  acid  and  basic 
dj^estuffs;  whereas  cotton,  which  is  practically  inert  as  far  as  chemical 
reactivity  is  concerned,  shows  no  pronounced  attraction  for  these  dyes; 
but  if  an  acid  mordant  is  added  to  the  cotton  fiber,  then  the  latter  exhibits 
the  power  of  combining  with  basic  dyes,  or  if  a  basic  mordant  (a  metallic 
oxide)  is  added  the  cotton  will  be  able  to  com])ine  with  the  acid  dyes. 
Furthermore,  in  the  case  of  mordant  dyes,  the  combination  between  the 
dyestuff  and  the  mordant  may  be  made  independent  of  the  fiber,  and  a 
chemical  reaction  undoubtedly  takes  place  in  the  formation  of  such  a  color- 
lake.     On  the  other  hand,  it  may  be  shown  that  the  substantive  colors 

*  This  mechanical  theory  may  hold  with  reason  in  the  case  of  dyeing  the  various 
mineral  colors  on  cotton;  for  instance,  where  the  colored  pigment  resulting  from  the 
double  decomposition  between  two  solutions  is  merely  precipitated  within  the  cells  of 
the  fiber;  or  in  the  dyeing  of  Indigo  where  the  dyestuff  is  of  a  i)igment  character.  But 
in  the  usual  forms  of  dyeing,  there  is  no  differentiation  possible  between  the  substance 
of  the  cell-wall  of  the  fibers  and  the  particles  of  coloring  matter,  for  even  under  the 
highest  powers  of  the  microscope  the  fiber  appears  to  be  uniformly  colored  just  like  an 
ordinary  solution  and  there  is  no  separation  of  pigment  matter  to  be  noticed.  Hence 
the  mechanical  theory  can  only  be  held  to  be  true  within  certain  narrow  limits. 

582 


MECHANICAL  THEORY   OF   DYEING  583 

dye  cotton  quite  readily  without  any  evidence  of  a  chemical  reaction. 
Also  almost  any  porous  substance  (even  such  substances  as  unglazed  por- 
celain, finely  divided  silica,  etc.)  will  take  up  a  dyestuff  from  solution 
(especially  the  basic  dyes)  and  become  truly  dyed  thereby.  Even  unmor- 
danted  cotton  will  dye  with  many  of  the  acid  and  basic  dyes  if  concen- 
trated solutions  are  employed,  and  the  colors  so  obtained  have  a  certain 
degree  of  fa':tness. 

Advocates  of  the  mechanical  theory  of  dyeing  often  compared  the  action 
of  the  fiber  in  dyeing  to  that  of  animal  charcoal  in  its  decolorizing  effect 
on  solutions  of  dyestuffs.  Though  this  comparison,  at  first  thought,  may 
appear  to  be  very  apt  and  to  be  a  strong  point  of  evidence  in  favor  of  the 
mechanical  theory,  nevertheless,  on  closer  scrutiny  and  consideration  the 
similarity  in  this  comparison  becomes  somewhat  doubtful.*     Of  course, 

*  The  chemical  theory  was  primarily  objected  to  by  the  partisans  of  the  mechanical 
theory  on  the  ground  that  there  was  no  definite  proportion  to  be  observed  between  the 
amount  of  the  fiber  and  the  amount  of  dyestuff  with  which  it  combines.  As  true  chem- 
ical reactions  take  place  only  between  definite  proportions  of  the  reacting  substances 
this  objection  would  seem  to  vitiate  the  chemical  theory  right  at  the  start.  But  on 
more  closely  inspecting  this  question  the  objection  loses  considerable  of  its  apparent 
value,  because  it  is  very  probable  that  the  reaction  between  the  dyestuff  and  the  sub- 
stance of  the  fiber  is  only  a  partial  one  and  may  be  more  or  less  superficial,  as  the  fiber 
may  become  considerably  changed  in  its  chemical  properties  by  reason  of  combining 
with  the  dyestuff.  That  there  is  any  molecular  ratio  between  the  masses  of  the  dye- 
stuff  and  the  fiber  taking  part  in  the  reaction  would  be  very  difficult  to  demonstrate 
or  to  disprove.  For  as  Vigrion  has  pointed  out  {Bull.  Soc.  Mulhouse,  1893,  page 
407)  it  is  no  doubt  very  probable  that  the  textile  fibers  possess  very  high  molecular 
weights  in  comparison  with  the  corresponding  weights  of  the  dyestuffs;  so  that  if  a 
fiber  with  a  molecular  weight  of,  say,  4000  units  combines  with  one  or  two  molecules 
of  a  dj-estuff  having  a  molecular  weight  of  only  200,  it  is  evident  that  it  would  be  very 
difficult  to  establish  the  law  of  definite  molecular  proportions  in  the  combination,  espe- 
cially where  it  is  furthermore  considered  that  the  fibers  are  very  likely  far  from  being 
chemically  homogeneous.  In  order  to  illustrate  this  point,  Rosenstiehl  (Bull.  Soc.  Mul- 
house, 1893,  pages  413,  417)  offers  the  following  example:  If  a  piece  of  silver  is  exposed 
to  the  action  of  sulphureted  hydrogen  gas  it  will  rapidly  become  blackened.  This 
coloring  effect  is  due  to  the  formation  of  silver  sulphide,  which  is  black,  and,  of  course,  it 
is  well  understood  and  recognized  that  a  chemical  combination  has  occurred  between  the 
metallic  silver  and  the  sulphureted  hydrogen  gas;  that  is  to  say,  a  definite  number  of 
molecules  of  silver  have  combined  with  a  definite  number  of  molecules  of  sulphur  (con- 
tained in  the  sulphureted  hydrogen  gas),  and  if  the  amount  of  silver  sulphide  formed  is 
determined  it  will  be  found  that  the  weights  of  the  silver  and  the  sulphureted  hydrogen 
entering  into  the  composition  of  the  silver  sulphide  are  in  definite  proportions  to  one 
another.  But  if  the  total  weigh*^  of  the  piece  of  silver  were  taken  and  the  total  weight 
of  the  sulphureted  hydrogen  likewise,  this  definite  proportion  between  the  weights  of 
the  two  would  not  be  found  to  hold,  for  the  simple  reason  that  the  chemical  union 
between  the  silver  and  the  sulphureted  hydrogen  has  only  been  a  partial  one,  as  the 
formation  of  the  black  silver  sulphide  has  been  merely  a  superficial  one,  a  fact  whii  h 
may  easily  be  shown  by  rubbing  the  blackened  surface  of  the  silver,  when  the  thin  layer 
of  silver  sulphide  will  be  removed  and  a  surface  of  the  bright  metal  will  again  be  exposed . 
This  same  idea  may  be  applied  to  the  theory  of  dyeing  by  supposing  that  the  chemical 


584  THEORY  OF   DYEING 

it  is  a  well-known  fact  that  when  some  liquids  containing  coloring  matters 
in  solution  are  filtered  through  a  layer  of  animal  charcoal  they  become 
decolorized,  the  coloring  matter  being  either  absorbed  or  destroyed  by  the 
charcoal.  But  it  has  also  been  found  that  the  solutions  of  many  dyestuffs 
which  dye  the  fibers  well  are  but  very  slightly  acted  on  by  animal  char- 
coal, while,  on  the  other  hand,  there  are  many  colored  solutions  which  are 
readily  and  completely  decolorized  by  animal  charcoal,  but  from  which  the 
fibers  do  not  take  up  any  color  at  all.  It  has  furthermore  been  shown  that 
the  action  of  animal  charcoal  on  solutions  of  those  coloring  m.atters  which  it 
decolorizes  is  probably  that  of  strong  oxidation,  causing  the  chemical 
decomposition  and  destruction  of  the  dyestuff.  This,  of  course,  is  a  totally 
different  action  from  that  of  the  fiber  which  combines  with  the  coloring 
matter  without  destroying  it.  The  oxidizing  action  of  the  charcoal  is 
caused  by  the  great  porosity  of  its  particles,  which  brings  the  oxygen  of  the 
air  into  very  intmiate  contact  with  substances  which  may  be  in  the  solu- 
tion treated  with  the  charcoal.  This  action  of  the  charcoal  is  very  similar 
to  that  of  finely  divided  platinum,  which  is  a  strong  oxidizing  agent. 
In  consequence  of  these  facts  it  may  be  said  that  the  dyeing  process  of  fibers 
can  hardly  be  compared  with  the  action  of  charcoal  in  decolorizing  solu- 
tions; or  at  best,  the  comparison  is  badly  chosen. 

The  mechanical  theory  of  dyeing  supposes  that  the  particles  of  the  dye- 
stuff  which  are  held  hi  solution  are  taken  up  by  the  fiber  by  the  force  of 
capillary  action,  and  are  then  held  by  the  fiber  in  the  interstices  between 
its  molecules.  Though,  as  already  pointed  out,  this  may  be  the  condition 
in  some  instances  of  dyeing,  yet  it  cannot  apply  to  all  processes  of  dyeing, 
otherwise  there  would  be  no  reason  why  all  dyestuffs  should  not  dye  all 
kinds  of  fibers  indiscriminately.     In  contradistinction  to  this,  of  course, 

union  between  the  dyestuff  and  the  coloruig  matter  is  superficial  and  incomplete  and 
similar  to  that  between  the  silver  and  the  sulphurated  hydrogen.  But  in  this  case 
the  layer  of  colored  substance  (the  silver  sulphide)  may  easily  be  removed  by  rubbing; 
and  furthermore,  if  a  cross-section  of  the  silver  piece  were  made,  it  would  show  but  a 
minute  layer  of  the  colored  substance,  the  rest  of  the  section  being  metallic  silver.  On 
the  other  hand,  it  docs  not  appear  that  mere  rubbing  will  remove  the  color  in  the  case  of 
dyeing  a  fiber;  though,  of  course,  it  may  be  said  that  here  the  deposition  of  the  layer  of 
colored  substance  is  not  only  on  the  external  svu-facc  of  the  fiber  as  a  whole,  but  is  also 
on  the  internal  surfaces  of  the  cells  of  which  the  fiber  is  composed.  But  again,  if  cross- 
sections  of  dyed  fibers  are  examined  microscopically  it  will  be  found  that  no  differentia- 
tion can  be  made  between  a  surface  layer  of  colored  substance  and  an  internal  portion  of 
substance  without  color,  such  as  would  naturally  be  the  case  if  the  dyeing  of  the  fiber 
were  analogous  to  the  blackening  of  the  silver  piece.  In  the  case  of  dyed  fibers,  a  micro- 
scopic examination  will  show  that  the  substance  of  the  fiber  is  uniformly  colored  through- 
out its  cross-section,  much  after  the  manner  of  a  solution.  It  is  at  this  point  that  the 
chemical  theory  is  somewhat  weak.  There  have  been  numerous  attempts  made  to 
observe  any  quantitative  proportions  existing  between  the  mass  of  the  fiber  and  the 
mass  of  the  coloring  matter  with  which  it  combines,  but  none  of  these  has  turned  out 
at  all  satisfactory. 


SOLID   SOLUTION   THEORY  585 

it  is  well  known  that  if  a  certain  coloring  matter  dyes  wool  it  does  not 
necessarily  dye  cotton.  This  mechanical  theory  also  would  not  explain 
why  the  same  dyestuff  gives  two  quite  different  shades  on  different  fibers, 
or  why  some  dyestuffs  give  colors  relatively  fast  to  light  on  one  fiber  while 
on  another  fiber  the  colors  are  comparatively  fugitive.  Owing  to  the  many 
discrepancies  existing  in  the  mechanical  theory  it  has  gradually  lost  its 
adherents  and  at  the  present  time  has  been  almost  entirely  discarded. 

With  the  present  knowledge  of  dyeing,  it  seems  more  reasonable  to 
assume  that  the  substance  of  the  fibers  is  capal^le  of  dissolving  such  bodies 
as  dyestuffs  and  mordants,  bringing  about  a  condition  which  we  know  as 
solid  solution,  which  merely  means  that  one  solid  substance  is  dissolved  in 
another  solid.  According  to  this  view  of  regarding  the  phenomena  of 
dyeing,  the  dissolved  coloring  matter  in  its  water-solution  passes  into  a 
fiber-solution.  There  are  many  factors  influencing  the  degree  and  rapidity 
of  this  form  of  solution,  among  which  the  most  important  appear  to  be 
the  chemical  activity  existing  between  the  dyestuff  (or  mordant)  and 
the  fiber,  the  heating  of  the  dyebath,  the  presence  of  various  chemicals 
in  the  dyebath  or  fiber,  and  the  mass  relations  between  the  fiber  and  dye- 
bath,  and  the  dyestuff. 

Limited  to  the  consideration  of  the  chemically  active  groups  of  dye- 
stuffs,  there  is  no  doubt  but  that  the  chemical  theory  has  much  of  truth 
in  its  conception.*     There  are  a  number    of    experimental    facts   which 

*  The  dyeing  of  substantive  colors  on  cotton  is  one  of  the  greatest  difficulties  in  the 
way  of  the  purely  chemical  theory.  These  dyes  fix  themselves  on  cotton  from  solutions 
of  a  neutral  character,  though  slightly  alkaline  baths  may  also  be  employed.  In  the 
practical  dyeing  of  this  class  of  colors  an  addition  of  common  salt  is  made  to  the  dye 
liquor,  but  this  addition  is  merely  for  the  purpose  of  lowering  the  solubility  of  the  dye- 
stuff  in  the  water  and  thus  causing  more  color  to  be  taken  up  by  the  fiber,'it  does  not 
effect  the  relation  between  the  coloring  matter  and  the  fiber.  By  those  who  try  to  force 
the  chemical  theory  on  every  case  of  dyeing  it  is  claimed  that  the  cotton  really  does 
combine  in  some  chemical  manner  with  the  dyestuff;  it  being  supposed  that  the 
"  hydroxyl  "  groups,  which  are  known  to  be  present  as  constituents  of  the  cellulose 
molecule,  have  sufficient  chemical  activity  to  unite  with  definite  groups  present  in  the 
dyestuff  molecule.  It  is  rather  remarkable,  however,  that  the  chemical  activity  of 
the  hydroxyl  groups  in  cellulose  should  appear  to  be  so  meager  towards  strong  bases 
and  acids  and  other  chemically  active  groups  while  they  are  able  to  exert  a  selective 
power  of  attraction  for  the  very  weak  chemical  groups  which  may  be  present  in  the 
substantive  dyes.  If  the  theory  held,  cotton  should  also  dye  with  many  acid  and  basic 
dyes,  even  more  readily  than  with  the  substantive  colors.  On  the  other  hand,  it  must 
be  borne  in  mind  that  most  of  the  substantive  dyes  are  derived  from  a  common 
fundamental  molecule  known  as  benzidine,  and  there  may  be  a  particular  chemical 
affinity  between  these  benzidine  compounds  and  the  cellulose  molecule  which  may  fur- 
nish a  real  chemical  basis  for  the  explanation  of  the  dyeing  phenomena  exhibited  by 
this  class  of  compounds;  but  as  these  substantive  dyes  also  color  wool  and  silk  about  as 
well  (and  in  some  cases  better)  as  they  do  cotton,  it  is  hardly  likely  that  such  an  explana- 
tion is  reasonable.  From  the  consideration  of  the  facts  as  observed  in  connection  with 
the  dyeing  of  substantive  colors  it  is  pretty  much  admitted  by  all,  at  the  present  time, 


586  THEORY   OF  DYEING 

support  it.  Let  us  take,  for  example,  the  dyeing  of  wool  with  Magenta. 
This  dyestuff  belongs  to  the  basic  class,  and  consists  of  rosaniline  (the 
color-base)  combined  with  hydrochloric  acid,  so  that  the  dj'-estuff  itself 
is  a  salt  (a  chemical  combination  l>etween  a  base  and  an  acid).  The 
solution  of  Magenta  (the  salt)  is  colored  red,  and  it  is  this  color  which  is 
also  produced  on  the  wool  in  dyeing  with  this  dyestuff.  The  color-base  of 
Magenta  (rosaniline),  however,  is  colorless  and  gives  a  colorless  solution. 
This  color-base  can  easily  be  prepared  from  the  color  salt  by  saturation 
of  its  solution  with  caustic  soda.  If  wool,  however,  is  boiled  in  a  solution 
of  rosaniline  (colorless)  it  will  become  dyed  red  in  the  same  manner  as 
if  a  solution  of  Magenta  (the  salt)  itself  had  been  used.  This  would  seem 
to  indicate  very  positively  that  the  color-base  has  united  with  some  acid 
constituent  of  the  fiber  to  give  a  salt,  and  it  is  therefore  necessary  to  assume 
that  a  chemical  reaction  has  taken  place  between  the  fiber  and  the  dj^e- 
stuff,  and  that  the  color-lake  so  formed  is  a  definite  chemical  compound. 

There  are  other  instances  of  a  similar  character  which  may  be  cited  in 
favor  of  the  chemical  theory.  Following  out  more  observations  in  connec- 
tion with  the  same  dyestuff  Magenta,  it  has  been  found  that  when  wool  is 
dyed  in  a  solution  of  Magenta  (rosaniline  and  hydrochloric  acid)  the  dye- 
bath  contains  free  hydrochloric  acid,  which  means  that  the  color-base  has 
combined  with  the  fiber,  leaving  its  previously  combined  acid  back  in  the 
bath.  There  is,  however,  another  point  of  view  from  this  phenomenon 
which  may  be  observed.  If  a  strip  of  porous  paper  (such  as  filter  paper  or 
blotting  paper)  be  hung  so  that  it  dips  into  the  solution  of  Magenta,  it  will 
be  found  that  the  solution  is  drawn  up  into  the  paper  above  the  surface  of 

that  the  dyestuff  merely  passes  from  its  solution  in  water  into  solution  in  the  fiber  being 
dyed,  for  it  has  been  shown  that  if  cotton  be  dyed  with  Benzopurpurin,  for  example, 
and  then  be  placed  in  a  boiling  bath  of  fresh  water  some  of  the  color  will  bleed  off  on  the 
cotton  and  redissolve  in  the  water,  and  this  may  be  repeated  several  times  by  treating 
with  successive  baths  of  fresh  boiling  water.  Of  course,  if  the  dj^eing  were  altogether 
simply  a  question  of  the  solution  of  the  dyestuff  in  the  fiber,  it  should  be  possible  to 
again  remove  all  of  the  dyestuff  from  the  fiber  by  repeated  boilings  in  water.  This 
reverse  operation,  however,  I  have  never  succeeded  in  accomplishing;  for  though  a 
considerable  amount  of  the  coloring  matter  may  be  stripped  from  the  cotton  by  such  a 
means,  a  limit  is  soon  reached.  Furthermore,  in  the  case  of  wool  and  silk  many  of  the 
substantive  dyes  give  colors  which  are  eminently  fast  to  washing.  Such  facts  would 
seem  to  indicate  that  besides  the  mere  solution-factor  of  the  fiber  for  the  dyestuff, 
there  must  be  some  other  determining  factor  which  influences  and  conditions  the  fixa- 
tion of  the  coloring  matter  by  the  fiber.  It  apjiears  that  most  of  the  substantive  dyes 
are  present  in  the  dyed  fiber  in  the  form  of  their  alkali-salts,  a  fact  which  can  be  proved 
by  showing  the  presence  of  the  alkali  in  the  ash  of  the  fiber.  This  same  thing  is  true  of 
quite  a  number  of  coloring  matters  dyed  on  wool  and  silk,  such  as  many  of  the  azo  dyes, 
and  more  especially  the  general  class  of  phthalein  dyes  including  the  Eosins  and  Rhoda- 
mines.  This  fact  would  seem  to  indicate  that  the  form  of  union  between  the  fiber  and 
the  dyestuff,  if  of  a  molecular  nature  at  all,  must  be  additive  in  character  and  probably 
without  material  modification  of  the  molecules  of  either  the  fiber  or  the  coloring  matter. 


CHEMICAL  THEORY 


587 


the  liquid  by  means  of  capillary  action,  and  it  will  furthermore  be  noticed 
that  after  a  time  two  distinct  areas  will  be  noticed  on  the  strip  of  paper,  the 
one,  next  to  the  surface  of  the  liquid,  will  be  colored  (the  same  as  the  solu- 
tion itself),  while  the  second,  located  above  the  first  area,  is  colorless.  If 
the  proper  tests  are  applied  it  will  be  found  that  the  liquid  of  this  second 
area  is  acid ;   and,  in  fact,  the  presence  of  free  hydrochloric  acid  in  this 


Fig.  277.— High-speed  Spring  Beetling  Machine.     (Mather  &  Piatt.) 

portion  may  readily  be  shown.  This  fact  would  seem  to  vitiate  (to  a  great 
extent  at  least)  the  testimony  offered  above  in  favor  of  the  chemical  theory; 
i.e.,  that  in  dyeing  wool  with  a  solution  of  Magenta,  the  color-base  was 
taken  up  by  the  fiber,  leaving  the  free  hydrochloric  acid  remaining  in  the 
residual  bath. 

A  study  of  this  condition,  together  with  many  others  of  a  similar 

character  which  are  found  to  occur  very  extensively  in  the  ordinary 

rocesses  of  dyeing-,  led  Knecht  (Berichte,  1888,  p.  1537,  2803)  to  propose  a 


588  THEORY   OF  DYEING 

theory  of  dyeing  based  on  the  idea  of  dissociation  of  the  molecules  of  the 
dyestiiff  when  in  solution.*  This  theory  of  Knecht,  in  fact,  brings  the 
various  facts  of  the  chemical  theory  of  dyeing  into  harmonious  accord  with 
the  more  widely  generalized  solution  theory.  The  dissociation  of  dis- 
solved substances  comes  directly  under  the  consideration  of  the  properties 
of  solutions,  and  the  chemical  functions  of  solution  depend  to  a  great  extent 
on  this  condition. 

Applying  this  idea  of  dissociation  now  to  the  theory  of  dyeing,  and 
taking  the  already  cited  case  of  the  dyeing  of  wool  with  a  solution  of 
Magenta,  we  have  the  following  considerations.  When  Magenta  (rosani- 
line  and  hydrochloric  acid)  is  dissolved  in  water  the  dyestuff  is  dissociated 
into  its  components,  viz.,  rosaniline  and  free  hydrochloric  acid.     This  fact 

*  In  order  clearly  to  understand  this  factor  in  the  discussion,  it  will  be  necessary  to 
explain  in  some  detail  just  what  is  meant  by  dissociation.  As  an  illustrative  example  on 
which  to  base  the  discussion,  let  us  take  the  case  of  a  solution  of  common  salt,  chemically 
known  as  sodium  chloride.  This  substance  in  its  molecular  constitution  is  made  up  of 
one  atom  of  sodium  and  one  atom  of  chlorine;  these  two  atoms  being  held  together  in  a 
chemical  union  to  form  a  distinct  molecule  of  sodium  chloride.  If  sodium  chloride  is 
dissolved  in  water  it  passes  into  a  form  evidently  different  from  that  which  it  possessed 
in  the  solid  state.  Whether  this  state  is  a  liquid  one  or  not  is  a  question  still  under  the 
consideration  of  physical  chemistry;  but  whatever  it  may  be,  sodium  chloride  in  this 
condition  exhibits  chemical  properties  quite  different  from  that  which  it  possessed  in 
the  solid  state.  For  instance,  the  characteristic  reaction  for  chlorine  is  its  avidity  for 
combining  with  silver  to  yield  a  highly  insoluble  white  compound  known  as  silver  chlo- 
ride; if  powdered  sodiimi  chloride  is  mixed  with  powdered  silver  nitrate,  both  being  in  a 
dry  condition  and  all  possibilities  of  the  presence  of  moisture  being  excluded,  no  chemical 
reaction  will  take  jilace  leading  to  the  formation  of  silver  chloride;  the  two  substances, 
sodium  chloride  and  silver  nitrate,  will  exist  side  by  side  without  any  tendency  to  react 
and  change  their  forms  of  chemical  combination.  If,  however,  these  two  substances  are 
employed  in  the  form  of  their  respective  solutions,  and  a  mixture  of  the  two  is  made, 
there  will  be  immediately  formed  a  white  precipitate  of  the  insoluble  silver  chloride 
while  a  corresponding  amount  of  sodium  nitrate  will  be  left  in  solution.  The  fact  of 
the  chemical  reactivity  of  a  substance  when  in  solution,  after  much  careful  study  and 
experimentation,  has  been  attributed  to  the  decomposition  of  the  molecules  of  the  sub- 
stance in  such  a  manner  that  the  separate  atoms  are  more  or  less  free  to  combine  with 
other  atoms  in  a  similar  condition  which  may  be  brought  into  their  immediate  proximity. 
When  the  sodium  chloride  is  dissolved  in  water,  it  is  supposed  that  the  molecule  is  split 
up — dissociated — into  the  separate  atoms  of  sodium  and  chlorine,  and  these  are  held  in 
some  physical  manner  by  the  solvent;  the  solution  of  silver  nitrate  may  be  considered 
in  the  same  manner,  and  when  the  two  solutions  are  brought  together  we  may  suppose 
that  the  atoms  of  chlorine  and  silver  are  free  to  combine;  and  as  fast  as  they  combine, 
as  the  resulting  compound  (the  silver  chloride)  is  insoluble  in  the  solvent,  the  former  is 
precipitated;  this  process  goes  on  until  all  of  the  silver  or  all  of  the  chlorine  (depending 
upon  which  one  is  in  excess)  has  been  used  up.  Dissociation,  then,  with  respect  to 
dissolved  substances  (and  this  is  the  only  phase  of  the  question  which  comes  under  our 
consideration  in  this  connection)  really  means  that  the  forces  which  hold  the  constituent 
atoms  of  the  molecule  together  as  a  distinct  physical  unit  are  more  or  less  broken  down, 
so  that  the  atoms  are  much  freer  to  enter  into  other  combinations  if  the  other  conditions 
for  such  are  favorable. 


DISSOCIATION  THEORY  589 

is  evidenced  by  the  experiment  of  the  selective  capillary  absorption  of  the 
dyestuff  solution  by  the  strip  of  blotting  paper.  Now  when  wool  is  placed 
in  this  solution  it  combines  with  the  rosaniline  base,  and  according  to 
Knecht,  this  combination  is  a  truly  chemical  one,  because  he  claims  that 
there  is  to  be  found  in  the  dyebath  an  amount  of  anmionium  chloride 
equivalent  to  the  amount  of  rosaniline  base  taken  up  by  the  wool.  This 
point  of  the  hypothesis,  however,  needs  to  be  substantiated  by  further  work 
in  quantitative  experiments  before  it  can  be  accepted  without  modification. 
Knecht  supposes  that  the  rosaniline  base  reacts  with  the  wool  in  such  a 
manner  as  to  displace  an  equivalent  amount  of  the  base  (ammonia)  nat- 
urally existing  in  the  fiber;  hence  the  occurrence  of  the  ammonia  compound 
in  the  dyebath  after  the  dyeing  operation  has  been  concluded.  Some  col- 
oring matters,  it  is  claimed,  are  not  very  greatly  dissociated  when  dis- 
solved in  water,  and  hence  these  do  not  dye  wool  as  readily  as  others  which 
are  more  completely  dissociated.  The  dyeing  properties  of  such  dyes, 
however,  may  be  considerably  enhanced  by  the  addition  of  an  alkali 
(such  as  borax,  soap  or  soda  ash)  to  the  dyebath,  whereby  the  color  base  is 
liberated  from  its  combination  with  the  acid;  or  the  same  effect  may  be 
obtained  by  increasing  the  acidity  of  the  wool  fiber  itself  by  chlorination. 
As  silk  possesses  acid  properties  of  a  more  pronounced  character  than  wool, 
it  will  combine  more  readily  with  the  general  class  of  basic  dyestuffs  in  a 
neutral  solution.  In  the  case  of  the  acid  dyes,  it  is  supposed  that  most  of 
them  are  not  very  highly  dissociated  in  solution,  hence  the  necessity  of 
adding  a  strong  mineral  acid  (such  as  sulphuric  acid)  to  the  dyebath,  which 
considerably  increases  the  dissociation  of  the  dissolved  dye  salt.  On  the 
other  hand,  there  are  a  few  of  the  acid  d^TS  which  possess  a  much  greater 
degree  of  dissociation  in  solution,  and  it  is  consequently  possible  to  dye  wool 
with  these  in  neutral  baths.* 

While  many  of  these  theories  may  explain  certain  examples  of  dyeing, 
none  of  them  offers  a  satisfactory  and  complete  explanation  of  the  whole 
general  field  of  dyeing.  This  may  be  accounted  for  by  the  fact  that  the 
dyestuffs  employed  are  of  varied  chemical  composition  and  properties, 
and  a  theory  which  would  satisfactorily  explain  the  behavior  of  one  dye- 
stuff  would  be  wholly  inadequate  to  explain  that  of  another  possessing 
entirely  different  chemical  characteristics.  Again,  even  if  we  confine 
our  attention  solely  to  the  consideration  of  the  textile  fibers  as  the  sub- 
stance to  be  dyed,  we  meet  with  variations  in  chemical  characteristics 

*  There  are  also  certain  dyes,  such  as  the  general  class  of  phthaleins,  which  appear 
to  be  taken  up  by  the  wool  fiber  in  the  form  of  their  alkali  salts,  rather  than  as  the  color 
acids;  this  is  shown  by  the  fact  that  the  alkali  may  be  detected  in  the  ash  of  the  dyed 
fiber.  In  such  a  case,  the  chemical  theory  again  fails  to  account  for  the  facts  as  observed; 
though  it  is  perfectly  permissible  for  us  to  suppose  that  the  fiber  dissolves  the  dye  salt 
in  toto  rather  than  any  component,  such  as  the  eolor-acid. 


590  THEORY   OF   DYEING 

as  well  as  wide  differences  in  physical  properties  and  structure ;  and  hence 
it  may  easily  be  understood  that  a  theory  which  would  explain  the  manner 
of  appljdng  dyestuffs  to  one  fiber  would  not  necessarily  be  the  proper 
one  to  explain  the  dyeing  of  another  kind  of  fiber.*  Wool,  for  example, 
is  very  different  from  cotton  in  both  its  chemical  characteristics  and  physical 
properties,  and  though  the  chemical  theory  of  dyeing  with  respect  to  wool 
with  acid  and  basic  coloring  matters  might  be  quite  acceptable,  never- 
theless, it  would  not  serve  in  any  maimer  to  explain  the  relation  between 
cotton  and  the  substantive  dyestuffs. 

Though  we  cannot  regard  the  chemical  activity  of  the  fiber  toward 
the  dyestuff  as  primari.y  the  cause  of  dyeing,  nevertheless  there  can  be  no 
doubt  but  that  this  factor  often  exerts  a  determining  influence  in  the 
process.  This  is  especially  true  when  we  consider  the  chemical  relations 
between  the  acid  and  basic  dyes  and  the  animal  fibers  wool  and  silk.  The 
chemical  combination  possible  between  the  fiber  and  the  dyestuff  in  thi-s 
case  no  doubt  determines  the  fixation  of  the  solution  of  the  coloring  matter 
in  the  substance  of  the  material  dyed.f 

*  Owing  to  the  very  diverse  materials  employed  in  dyeing  and  their  various  relations 
to  the  different  fibers,  it  is  hardly  possible  that  any  one  theory  will  be  general  enough  to 
explain  all  cases  of  dyeing,  and  it  is  probable  that  any  one  of  the  theories  briefly  out- 
lined above  may  properly  account  for  a  certain  set  of  phenomena  while  failing  to  fit  in 
with  the  demands  of  other  reactions  in  dyeing.  The  explanation  of  any  particular 
dyeing  process  must  take  into  account  the  known  facts,  and  it  is  foolish  to  attempt  to 
fit  all  processes  into  the  terms  of  a  single  academic  theory  that  may  only  partially  repre- 
sent the  actual  facts. 

t  If  a  substance  is  soluble  in  two  solvents,  and  both  of  the  latter  are  present  simul- 
taneously, the  substance  will  be  distributed  between  the  two  solvents  in  amounts 
depending  on  the  relative  solubilities  in  the  latter.  Applying  this  law  to  the  con- 
ception of  the  dyeing  process,  wc  have  th  water  and  the  fiber  as  the  two  solvents  and 
the  dyestuff  as  the  substance  to  be  dissolved.  If  the  dyestuff  is  much  more  soluble 
in  the  water  than  in  the  fiber  we  will  find  that  in  dyeing  the  latter  it  will  take 
up  the  color  until  a  certain  point  is  reached,  and  then  no  more  color  will  go  on,  although 
there  may  still  be  a  large  amount  of  color  left  in  the  dj-ebath.  A  point  of  equilibrium 
has  been  reached  between  the  solubility  of  the  dyestuff  in  the  fiber  and  in  the  water  and 
it  will  only  be  possible  to  dissolve  more  of  the  dyestuff  in  the  fiber  by  altering  the  con- 
ditions determining  the  solubility  of  the  color  in  the  water.  The  relative  solubility  of 
the  coloring  matter  in  the  fiber  is  commonly  known  as  the  "  exhaustion  "  of  the  dye- 
bath;  consequently  if  the  dyestuff  is  much  more  soIuIjIo  in  water  than  it  is  in  the  fiber 
the  exhaustion  of  the  bath  will  be  small,  whereas  if  the  ojjposite  is  the  case  the  exhaustion 
will  be  great.  In  some  cases,  the  exhaustion  of  the  bath  is  almost  perfect;  that  is  to  say, 
practically  all  of  the  color  is  taken  up  by  the  fiber.  This  would  indicate  that  the  so'u- 
bility  of  the  dyestuff  in  the  water  is  almost  negligible  compared  with  its  solubility  in  the 
fiber.  It  is  also  probable  that  in  such  cases,  a  chemical  reaction  between  the  dj^estuff 
and  the  fiber  (or  some  mordant  on  the  fiber)  may  e.xert  considerable  influence;  for  if 
such  a  chemical  union  did  take  place  there  may  be  the  formation  of  an  insoluble  com- 
pound which  would  leave  the  fiber  free  to  dissolve  more  of  the  colormg  matter  from  the 
water,  which  in  turn  would  be  precipitated  and  fresh  amounts  would  again  be  dissolved 
by  the  fiber,  and  this  process  would  keep  up  until  all  of  the  dyestuff  had  been  removed 


NATURE  OF  THE  FIBERS  591 

The  process  of  dyeing  may  be  said  to  be  a  phenomenon  primarily 
deaUng  with  solutions,  for  in  all  cases  of  true  dyeing  the  coloring  matter, 
or  the  substances  which  eventually  go  to  make  up  the  coloring  matter,  are 
employed  in  the  form  of  solutions.  As  dyeing  has  more  especial  reference 
to  the  coloring  of  the  textile  fibers  in  one  form  or  another,  and  as  the  color- 
ing matters  are  practically  used  solely  in  a  solution  in  water,  it  will  be 
unnecessary  for  us  to  go  beyond  the  consideration  of  these  two  factors. 
As  far  as  any  relations  which  may  exist  between  the  water  solvent  and 
the  dyestuff,  it  may  be  said  that  they  would  all  fall  under  the  proper 
considerations  of  the  theory  of  solutions;  and  furthermore,  any  relations 
which  may  exist  between  the  fibers  and  the  solvent  would  also  be  con- 
sidered under  the  same  general  subject;  the  last  set  of  relations  we  have  to 
deal  with  (that  between  the  fibers  and  the  coloring  matter)  would  nat- 
urally be  considered  as  relations  existing  between  two  solids,  or  rather  a 
solid  and  a  dissolved  substance. 

In  the  first  place,  let  us  consider  for  a  while  the  nature  of  the  textile 
fibers  *  without  reference  to  any  connection  it  may  have  with  the  theory 
of  solution.  All  of  the  textile  fibers  may  be  considered  as  substances  of  a 
colloidal  nature — that  is  to  say,  they  are  not  crystalline  in  structure.  It 
may  be  said  that  they  somewhat  resemble  a  solid  jelly;  in  the  case  of 
the  animal  fibers  this  is  especially  so,  for  both  silk  and  wool  are  of  a  gelat- 

from  solution  in  the  water  or  until  the  chemical  action  between  the  dyestuff  and  fiber 
had  become  complete.  This  condition  probably  holds  in  the  case  of  dyeing  Alizarine 
colors  on  mordanted  wool,  as  in  this  case,  without  doubt  the  dyestuff  forms  a  chemical 
compound  with  the  mordant;  hence  we  find  that  these  dyes  give  a  very  thorough 
exhaustion  of  the  bath.  On  the  other  hand,  in  the  dyeing  of  cotton  with  substantive 
colors,  there  is  no  reason  to  suspect  any  chemical  union  between  the  fiber  and  dyestuff, 
and  we  find  that  the  exhaustion  is  relatively  poor. 

*  That  the  chemical  nature  of  the  fiber,  however,  does  enter  as  a  considerable  factor 
into  the  dyeing  process  is  also  shown  by  the  fact  that  often  the  fiber  may  be  so  altered 
in  its  chemical  properties  as  to  exhibit  quite  a  marked  change  in  its  relation  to  the  dye- 
stuff.  When  wool,  for  instance,  is  chlorinated  (that  is,  treated  with  a  solution  of  bleach- 
ing powder,)  it  exhibits  a  largely  increased  affinity  for  many  coloring  matters,  especially 
towards  certain  basic  and  substantive  dyes.  The  cellulose  of  vegetable  fibers  is  rather 
easily  oxidized  by  certain  substances,  such  as  chlorine,  chromic  acid,  hypochlorites,  etc. 
Probably  the  substance  known  as  oxycellulose  is  formed,  and  this  possesses  the  property 
(not  possessed  by  ordinary  cellulose)  of  dyeing  directly  with  many  basic  coloring  matters, 
while  its  reactivity  with  many  of  the  substantive  dyes  is  noticeably  diminished.  In  the 
same  manner,  by  the  nitration  of  cellulose  it  acquires  a  strong  affinity  for  the  basic  dyes. 
The  cellulose  of  artificial  silk,  for  example,  may  be  readily  dyed  with  such  basic  colors 
as  Methylene  Blue,  Malachite  Green,  Magenta,  etc.  By  treating  wool  with  a  solu- 
tion of  sulphuric  acid  and  then  washing  thoroughly  to  remove  all  uncombined  acid,  we 
find  that  the  fiber  possesses  a  considerably  increased  affinity  for  most  acid  dyes.  Accord- 
ing to  the  chemical  theory  the  combination  of  the  wool  with  the  acid  should  decrease  the 
basicity  of  the  fiber,  and  consequently  should  lessen  its  affinity  for  acid  dyes ;  but  on  the 
contrary,  we  see  that  the  "  acidified  "  wool  dyes  better  with  acid  dyes  than  ordinary 
wool.     No  doubt  the  acid  colors  are  more  soluble  in  the  acidified  wool. 


592 


THEORY   OF   DYEING 


inous  nature;  and  even  with  cotton,  and  the  vegetable  fibers  in  general, 
the  fiber  consists  of  a  membrane  or  vegetable  tissue  which  may  be  said  to 
resemble  physically  a  dried  starch  filament.  In  both  the  animal  and 
vegetable  fibers,  therefore,  it  may  be  seen  that  this  colloidal  nature  is 
very  marked,  and  is  really  the  one  physical  property  which  both  classes  of 
fibers  possess  in  common.      Now  a  jelly  or  gelatinous-like  substance, 


Fig.  278. — Small  Fulling  Washer  for  Flannels,  etc. 


though  it  is  really  a  solid,  nevertheless  possesses  some  of  the  character- 
istics of  a  licjuid,  especially  with  reference  to  the  property  of  dissolving 
substances.  Starch  paste,  jellies  made  from  vegetable  gums,  or  animal 
gelatin,  or  albumin,  all  have  the  power  of  dissolving  various  substances 
such  as  metallic  salts  or  other  inorganic  materials,  as  well  as  dyestufi"s  or 
similar  organic  substances.  Therefore  it  may  l)e  said  that  the  fibers  them- 
selves pos!  "^ss  lome  of  the  same  kind  of  properties  which  we  know  to  be 


SOLUTION   OF   DYES  IN   FIBERS  593 

characteristic  of  similar  colloidal  bodies.  It  may  be  perfectly  proper 
then  to  say  that  wool,  silk,  and  cotton  are  capable  of  dissolving  mordants 
or  dyestuffs  in  the  same  general  manner  that  any  other  solvent  would. 

If  we  take  a  stiff  jelly  prepared  from  animal  gelatin  or  a  vegetable  gum 
such  as  agar-agar,  for  example,  and  place  it  in  a  solution  of  ferric  chloride, 
the  jelly  will  absorb  some  of  the  metallic  salt  from  its  aqueous  solution  and 
form  with  it  really  a  solution  itself,  which  may  be  evidenced  by  placing  the 
jelly  into  a  solution  of  potassium  ferrocj^anide,  when  soon  the  whole  mass 
of  jelly  will  be  colored  blue  by  the  formation  of  Prussian  Blue  due  to  the 
combination  of  the  ferrocj^anide  with  the  ferric  salt.  In  the  same  way,  if 
the  jelly  be  placed  in  a  solution  of  a  dyestuff,  it  will  be  found  that  the  col- 
oring matter  will  gradually  be  absorbed  and  dissolved  in  the  jelly. 
This  illustration  may  be  taken  to  represent  in  some  degree  the  phenomena 
which  occurs  in  the  dj^eing  of  the  various  textile  fibers.  The  dyestuff 
may  be  considered  as  being  dissolved  in  the  substance  of  the  fiber,  just  as  a 
solution  of  the  dyestuff  consists  of  the  solid  coloring  matter  dissolved,  in 
water.  And  the  same  conception  may  be  held  as  to  the  relation  between 
the  fiber  and  the  various  metalUc  or  other  mordants  with  wliich  it  may  be 
treated  previous  to  dyeing. 

The  difference  in  the  behavior  of  the  same  dj^estuff  towards  different 
fibers  may  be  explained  by  supposmg  that  the  various  fibers  exert  a  dif- 
ferent solvent  action,  just  as  different  liquids  exert  a  different  solvent 
action  on  the  same  soUd  material.  For  instance,  if  wool  is  boiled  in  a  solu- 
tion of  Orange  II,  the  color  will  be  rapidly  taken  up  and  the  fiber  becomes 
dyed;  if  cotton,  however,  is  used,  the  fiber  will  only  become  slightly 
tinted.  In  other  words,  the  wool  has  a  strong  solvent  action  with  regard 
to  this  coloring  matter  while  the  cotton  hardly  dissolves  it  at  all.  On  the 
other  hand,  if  Mikado  Yellow  is  used  as  the  dyestufT,  the  wool  will  be  left 
practically  undyed  while  the  cotton  will  be  deeply  colored ;  so  in  this  case 
it  may  be  said  that  the  Mikado  Yellow  is  insoluble  in  wool  though  readily 
soluble  in  cotton.  As  a  rule,  the  animal  fibers,  wool  and  silk,  exhibit  sol- 
vent properties  which  are  very  similar,  and  on  the  other  hand,  cotton, 
Hnen,  and  the  vegetable  fibers  in  general,  exhibit  similar  properties. 
This  may  no  doubt  be  conditioned  very  largely  by  the  chemical  nature  of 
the  two  classes  of  fibers,  though  we  also  have  cases  where  there  appear  to 
be  distinctive  properties  between  wool  and  silk.  For  instance,  if  silk  is 
dyed  in  an  acidulated  bath  with  Indigo  Carmine,  it  will  take  up  the  coloring 
matter  quite  readUy,  but  if  a  mixture  of  silk  and  wool  be  dyed  in  such  a  solu- 
tion, it  will  be  found  that  the  wool  will  take  up  the  color  almost  exclusively, 
the  silk  only  becoming  shghtly  tinted.  Tliis  is  explained  by  supposing 
that  the  wool  dissolves  the  dyestuff  much  more  readily  than  the  silk. 

There  are  several  factors  which  may  influence  considerably  the  solvent 
action  of  the  fiber  for  the  coloring  matter.     Heat  is  one  of  the  principal 


594  THEORY   OF   DYEING 

of  these.*  As  a  rule,  dyestuffs  are  much  more  soluble  in  the  fibers  at  a 
boiling  temperature  than  at  lower  ones ;  on  this  account,  the  dyeing  process 
is  mostly  carried  out  in  a  boiling  solution.  If  wool,  for  instance,  is  dyed 
in  a  cold  solution  of  Xaphthol  Yellow  it  will  take  up  but  very  httle  color; 
but,  if  it  is  dyed  in  a  boiling  solution  of  this  dyestuff,  it  will  become  colored 
an  intense  yellow.  This  is  explained  by  sup])()sing  that  at  low  tempera- 
tures, the  ch'estuff  is  onh'  slightlj'  soluble  in  the  fiber,  whereas  at  higher 
temperatures  its  solubihty  in  the  fiber  becomes  much  increased. 

The  presence  of  certain  chemicals  in  the  dycl^ath  also  has  an  important 
influence  in  the  regulation  of  the  dyeing.  In  the  case  of  acid  dj-es,  the 
presence  of  acid  (such  as  sulphuric  or  acetic)  liberates  the  free  color-acid 
from  the  dyestufT  salt  and  thus  promotes  and  accelerates  the  dyeing  by 
allowing  of  the  ready  and  complete  combination  between  the  filxT-ljase 
and  this  color-acid.  We  maj'  represent  this  reaction  somewhat  in  the 
following  graphical  manner: 

color-acid  :  soda     +    H2SO4    =     color-acid  :  hj-drogen 


dyestuff  salt         sulphuric  acid  free  color-acid 

+  Xa2S0-f 


sodium  sulphate 

Color-acid  +  wool-base  =  color-lake. 

If  wool,  for  example,  is  boiled  in  a  solution  of  Ponceau  it  will  only  take  up 
a  rather  limited  am.ount  of  the  color,  however  long  the  boiling  may  l>e  pro- 
longed; but  if  a  small  quantity  of  sulphuric  acid  is  added  to  the  solution, 
the  wool  will  become  dyed  quite  a  hea\-y  color  and  practically  all  of  the  dye 
is  taken  up  by  the  fiber.  It  might  be  possible  to  explain  this  case  of  dye- 
ing in  another  way  than  having  resort  to  the  chemical  theory  of  the  com- 
bination of  the  color-acid  with  the  wool-base;  it  might  be  claimed  that  the 
addition  of  the  acid  simply  increased  the  solubility  of  the  dye  in  the  sub- 
stance of  the  fiber  and  was  not  necessarily  evidence  of  any  chemical  com- 
bination on  the  part  of  the  wool.  But  owing  to  the  fact  that  it  has  been 
found  that  the  addition  of  acid  to  the  dyebath  is  necessary  in  cases  of  a 
large  number  of  the  dyes  belonging  distinctively  to  the  color-acid  group  of 
dyes,  it  is  more  reasonable  to  suppose  that  the  chemical  explanation  is  a 

*  Heat  appears  to  play  an  important  role  in  dyeing  as  it  docs  in  all  forms  of  solution. 
By  elevating  the  temperature  the  mobilitj'  of  the  molecular  aggregates  of  both  the 
dyestuff  and  the  fiber  is  increased  so  as  to  allow  of  a  more  intimate  mixture  of  these 
molecules  with  one  another.  The  rapidity  and  degree  of  dyeing  is  nearly  always  greater 
in  a  hot  dyebath  than  in  a  cold  one;  and  the  proper  regulation  of  this  temperature  per- 
mits the  dyer  to  so  regulate  the  taking-up  of  the  color  by  the  fiber  as  to  obtam  even  and 
well-penetrated  dyeings. 


CHEMISTRY   OF   DYEING   PROCESS  595 

closer  approximation  to  the  truth.  In  this  connection,  however,  it  is  to  be 
observed  from  the  other  point  of  view  that  there  are  some  of  the  acid  dyes 
which  dye  on  wool  very  well  from  a  neutral  bath;  it  is  true  that  the  num.- 
ber  of  these  is  rather  limited,  and  the  dyeing  may  be  explained  by  the  fact 
that  the  dyestuff  when  dissolved  in  the  bath  is  more  or  less  dissociated  into 
the  free  color-acid  and  the  sodium  salt,  and  the  reaction,  therefore,  is  still 
a  question  of  the  chemical  combination  between  the  color-acid  and  the 
wool-l)ase.  But  it  is  not  well  to  be  too  certain  that  this  represents  the  whole 
truth;  it  is  quite  possible  that  with  the  acid  dyes  both  the  chemical  reac- 
tion of  the  color-acid  and  wool-base  and  the  solution  reaction  between  the 
fiber  and  the  coloring  matter  come  into  play.  It  may  be  simply  that  the 
free  color-acid  of  the  dye  is  more  soluble  in  the  fiber  than  the  dye  itself.* 

In  some  cases  the  addition  of  alkalies  to  the  dyebath  somewhat  increases 
the  solubility  of  the  dj-estuff  in  the  fiber;  this  is  particularly  true,  for  exani- 
ple,  in  the  case  of  certain  substantive  dyes  with  relation  to  the  cotton  fiber. 
If  cotton  is  dyed  in  a  neutral  solution  of  Benzopurpurin  4B  it  will  be 
found  that  only  a  relatively  small  quantity  of  the  color  is  taken  up  by  the 
fiber  while  most  of  the  dye  will  remain  in  solution  in  the  dyebath.  The 
addition  of  some  soda  ash  to  the  bath,  however,  will  cause  more  of  the  dye 
to  be  absorbed,  and  this  notwithstanding  the  fact  that  the  dye  is  more 
soluble  in  the  alkaline  liquor  than  in  the  neutral  bath.  The  addition 
of  neutral  salts  that  Avill  decrease  the  relative  solubility  of  the  dye  in 
the  water  will  also  serve  the  same  purpose.  If,  for  instance,  in  the  case  of 
Benzopurpurin  4B,  some  common  salt  is  added  to  the  dye  solution  the 
color  will  feed  on  to  the  fiber  much  better.  It  is  not  probable  here  that 
the  solvent  action  of  the  fiber  is  increased,  but  sunply  that  the  solvent 
action  of  the  bath  is  decreased,  causing  a  new  equilibrimn  to  be  established 
between  the  relative  solubilities  of  the  fiber  and  the  bath. 

The  use  of  glaubersalt  in  the  dyeing  of  acid  and  basic  dyes  presents  a 
different  problem  from  that  of  salt  (or  even  glaubersalt  itself)  in  the  dyeing 
of  substantive  dj^es.  The  glaubersalt,  as  we  know,  is  used  for  the  purpose 
of  obtaining  more  level  colors  and  seems  to  retard  the  absorption  of  the 
dye  by  the  fiber  and  also  to  increase  its  solubility  in  the  dyebath.  The 
last  statement  is  borne  out  by  the  fact  that  wool  dyed  with  an  acid  color  is 
more  or  less  stripped  when  boiled  in  a  solution  of  glaubersalt,  while  it  might 
not  be  so  affected  when  boiled  in  plain  water.     One  explanation  of  the 

*  Some  of  the  color-salts  are  much  more  soluble  in  wool  than  others,  and  this  explains 
whj'  certain  of  the  acid  dj^es  may  be  applied  to  this  fiber  comparatively  well  in  neutral 
baths.  It  may  also  be  remarked  that  the  free  color-acids  of  the  acid  dyestuffs  are  much 
less  soluble  in  water  than  their  salts,  and  as  the  exhaustion  of  the  color  from  the  dyebath 
by  the  fiber  is  really  dependent  on  the  relative  solubilities  of  the  coloring  matter  in 
the  water  and  the  fiber,  it  may  be  seen  that  the  addition  of  the  acid  to  the  bath  also 
decreases  the  solubility  of  the  coloring  matter  in  the  water,  and  hence  increases  its  rela- 
tive solubility  in  the  fiber. 


596  THEORY  OF   DYEING 

action  of  glaubersalt  is  that  its  presence  serves  to  distribute  more  per- 
fectly the  dj-estiiff  molecules  through  the  fiber  substance;  it  may  be  said 
to  impede  the  progress  of  the  dyestuff  molecules  in  their  passage  from 
the  water  solution  to  that  of  the  fiber.  The  number  of  glaubersalt  mole- 
cules is  very  large  compared  vnth  the  number  of  the  dyestuff  molecules, 
and  hence  its  action  may  be  compared  to  that  of  a  ^arge  crowd  of  people 
impeding  the  progress  of  a  man  walking  towards  a  definite  point.  This 
explanation,  however,  is  not  perfectly  satisfj-ing.  From  another  point 
of  view  it  may  be  considered  that  the  effect  of  the  glaubersalt  is  to  retard 
the  action  of  the  acid  in  breaking  up  the  dye  into  the  color-acid  and  also 
to  diminish  the  solubility  of  the  dye  in  the  fiber. 

The  basic  dyes  appear  to  become  dissociated  when  dissolved  in  water; 
that  is  to  say,  the  color-base  of  these  dyes  becomes  spontaneously  separated 
from  the  acid  with  wliich  it  is  combined  in  the  form  of  its  dyestuff-salt ; 
and  the  free  color-base  thus  formed  combines  readily  with  the  acid  com- 
ponent of  the  fiber  to  form  the  color-lake.  Therefore  the  basic  dyes  can 
be  applied  to  the  animal  fibers  in  a  neutral  dyebath.  As  a  rule,  however, 
they  are  taken  up  too  rapidly  by  the  fiber  to  allow  of  even  dyeing,  so  the 
bath  is  usually  made  slightly  acid  (with  acetic  acid)  in  order  to  retard  the 
dyeing  action. 

The  mass-relations  existing  between  the  fiber,  the  dyebath,  and  the 
dyestuff  also  have  an  important  influence  in  the  dyeing  reaction.  It  would 
be  natural  to  expect  that  the  gi-eater  the  concentration  of  the  dyebath, 
that  is,  the  greater  the  mass  of  the  d^'estuff  in  proportion  to  the  mass  of 
the  water,  the  more  color  will  be  taken  up  by  the  fiber.  The  same,  of 
course,  is  true  when  the  mass  of  the  fiber  is  greater  in  proportion  to  that  of 
the  water.* 

2.  Theory  of  Dyeing  in  Relation  to  Pigment  Colors. — The  views  on 
the  theory  of  dyeing  which  have  been  so  far  given  cover  those  problems 
which  have  to  do  with  the  general  classes  of  coal-tar  dj'^es.  We  have, 
however,  other  classes  of  dyeing  to  which  a  somewhat  different  inter- 
pretation must  be  given.  If  a  skein  of  cotton  yarn  is  steeped  in  a  solution 
of  lead  acetate  there  will  naturally  be  a  considerable  amount  of  the  solution 
absorbed  by  the  fiber  through  capillary  action ;  the  lead  salt,  however,  has 
not  dissolved  in  the  fiber  or  become  at  all  permanent^  fixed  therein,  as  it 
may  practically  all  be  removed  by  repeated  washings  in  water.     If,  how- 

*  As  already  pointed  out,  this  amount  is  dependent  on  the  relative  solvent  power 
of  the  water  and  the  fiber;  hence,  other  things  being  equal,  if  there  is  a  large  amount  of 
fiber,  the  latter  will  take  up  much  less  color  than  if  the  conditions  were  reversed;  that  is 
to  say,  the  fiber  will  be  dyed  more  deeply  in  concentrated  solutions  than  in  dilute  ones,  a 
result  which  would  naturally  be  expected.  In  using  dyes  which  are  very  soluble  in 
water,  therefore,  it  is  customary  to  employ  "short"  dyebaths;  that  is,  as  small  a 
quantity  of  water  as  possible  is  used;  whereas,  when  the  dyestuff  is  much  less  soluble, 
it  is  customary  to  employ  more  dilute  dyebaths. 


DYEING  WITH  PIGMENT  COLORS  597 

ever,  the  skein  of  yarn  is  not  washed  after  being  so  impregnated  with  the 
solution  of  lead  acetate,  but  is  simply  squeezed  so  as  to  remove  the  surface 
liquor,  and  is  then  passed  into  a  solution  of  bichromate  of  potash,  it  will 
become  dyed  a  l^eautiful  deep  yellow,  and  th .  coloring  matter  consists  of 
Chrome  Yellow.  The  dyeing  process  in  this  instance  cannot  be  regarded 
in  any  other  way  but  as  a  deposition  of  an  insoluble  pigment  in  the  pores  of 
the  fiber.  If  a  solution  of  lead  acetate  is  mixed  with  one  of  bichromate  of 
potash,  irrespective  of  the  presence  of  any  fiber  at  all,  the  same  yellow  pig- 
ment will  be  formed  by  a  double  decomposition  between  the  two  chemicals 
resulting  in  the  formation  of  an  insoluble  lead  chromate.  If  this  reaction 
takes  place  in  the  presence  of  the  fiber,  the  insoluble  pigment  will  be  pre- 
cipitated in  such  a  manner  that  it  will  be  contained  in  the  pores  and  inter- 
stices in  the  fiber  with  the  result  that  the  latter  will  become  uniformly 
colored.     If,  however,  a  filler  dyed  in  such  a  manner  be  examined  under  the 


Fig.  279. — Expanding  and  Equalizing  Machine. 

microscope,  it  will  be  observed  that  the  particles  of  precipitated  pigment 
may  be  readily  observed;  a  condition  which  will  not  be  found  in  the  case  of 
a  fiber  dyed  with  the  usual  dyestuffs. 

The  general  process  of  dyeing  of  which  Chrome  Yellow  is  the  type, 
extends  to  practically  all  cases  of  mineral  or  pigment  dyes,  such  as  Iron 
Buff,  Manganese  Brown,  etc.  In  all  such  cases  there  is  simply  a  precipi- 
tation by  chemical  reaction  between  two  soluble  salts  in  the  fiber  of  an 
insoluble  pigment.  The  same  is  also  true  of  Indigo  dyeing.  In  this  case 
the  fiber  is  impregnated  with  a  solution  of  indigo-white,  which  is  subse- 
quently oxidized  and  the  resulting  insoluble  blue  Indigo  is  precipitated  as  a 
pigment  in  the  fiber.  This  process  of  dyeing  may  be  called  dyeing  by 
"  impregnation,"  and  is  essentially  different  in  its  nature  from  the  ordinary 
processes  of  dyeing  where  the  true  dyestuffs  are  employed.  There  are  also 
other  cases  where  the  coloring  matter  is  built  up  or  formed  in  the  fiber  by 
chemical  means;    such,  for  instance  is  the  dyeing  of  cotton  with  Parani- 


598  THEORY  OF  DYEING 

tramline  Red,  and  other  coloi"S  of  this  same  class.  In  this  case,  the  cotton 
is  first  impregnated  with  a  solution  of  one  of  the  eventual  components  of 
the  dyestuff  to  Ix?  formed;  i.e.,  beta-naphthol.  The  material  so  prepared 
is  then  brought  m  contact  with  the  second  ingredient  of  the  dyestuff; 
i.e.,  the  diazotized  solution  of  paranitraniline.  The  resulting  compound 
is  an  insoluble  red  pigment,  and  consequently  this  method  of  dyeing  must 
bo  regarded  as  coming  under  the  "  impregnation  "  process. 

3.  Theory  of  Dyeing  in  Relation  to  Compound  Shades. — 80  far  we 
have  only  considered  the  case  of  the  relation  between  the  fiber  and  one 
single  coloring  matter.  'VMien  several  dyestuffs  are  employed  simulta- 
neously the  relations  are  more  complex.  If  the  dyes  employed  possess 
efjuivalent  "  affinities  "  for  tb.e  fil>er,  they  will  l^e  taken  up  or  dissolved  by 
the  filjer  uniformly;  but  if,  hov.ever,  theu"  "  affinities  "  are  different,  as 
is  more  generally  the  case,  then  the  coloring  matter  possessing  the  strongest 
attraction  for  the  fiber  will  ])e  taken  up  from  the  dye  solution  first,  other 
things  being  equal;  and  those  dyes  ha^ing  a  weaker  attraction  will  be 
taken  up  in  proportionately  smaller  amounts  during  the  same  period  of 
dyeiiig.  From  this  it  is  e\'ident  that  the  dyestuffs  ha\ing  the  greatest 
affinity  for  the  filler  will  ])e  exhausted  from  the  dyebath  more  quickly  and 
more  completely.  Suppose,  for  instance,  that  a  reddish  brown  is  to  be 
dyed  on  wool,  there  being  used  for  tliis  purpose  Fast  Red  A,  Fast  Yellow 
and  Patent  Blue  V,  as  the  dj'estuffs.  In  the  first  period  of  the  dj'eing  opera- 
tion most  of  the  Fast  Red  A  will  be  taken  up  by  the  fiber  together  with 
small  cjuantitips  of  the  yellow  and  blue  dyestuffs.  On  continuing  the  dye- 
ing process  m  a  short  while  the  red  coloring  matter  will  l^e  ahnost  com- 
jjletelj'  exhausted  from  the  bath,  and  the  color  of  the  dye  Hquor,  which 
at  first  was  brown,  becomes  olive,  then  green,  and  finally  as  most  of  the 
yellow  is  slowly  taken  up  Ijy  the  fiber,  the  bath  becomes  ahnost  pure  blue 
in  co'or,  due  to  the  residue  of  Patent  Blue  which  is  left. 

The  inter-relations,  however,  between  the  affinities  of  several  dj^s  when 
applied  simultaneouslj'  does  not  hold  for  different  proportions  among  the 
amount  of  dyes  that  may  be  present.  For  instance,  in  the  above  example, 
if  the  amount  of  Fast  Red  is  decreased,  the  fiber,  of  course,  will  no  longer 
take  up  the  same  actual  quantities  of  j-ellow  and  blue  dj'es  as  before, 
l)ut  it  is  hkely  that  it  will  absorb  more.  In  other  words,  the  masses  of  the 
several  dyes  present  in  varied  colors  have  a  considerable  influence  on  the 
relative  affinities  of  the  dyes  for  the  fil>er.  This  idea  may  be  illustrated 
in  the  following  manner:  Suppose  we  have  the  following  combination  of 
dyes : 

1  per  cent  of  Fast  Red  A 
1  per  cent  of  Fast  Yellow 
1  per  cent  of  Patent  Blue  V 


DYEING  MIXED   FIBERS  599 

The  respective  amounts  actually  taken  up  by  the  fiber  may  be  as  follows  : 

1  per  cent  of  Fast  Red  A 
f  per  cent  of  Fast  Yellow 
5  per  cent  of  Patent  Blue  V 

Whereas,  if  the  following  combination  of  dyes  had  been  used : 

y\j  per  cent  of  Fast  Red  A 
1  per  cent  of  Fast  Yellow 
1  per  cent  of  Patent  Blue  V 

there  would  l)e  taken  up  by  the  fibers: 

^\,  per  cent  of  Fast  Red  A 
1  per  cent  of  Fast  Yellow 
^  per  cent  of  Patent  Blue  V 

In  other  words,  a  change  in  the  proportion  of  dyestuffs  present  will 
seriously  alter  the  proportion  of  coloring  matter  absorbed  by  the  fiber. 

4.  Theory  of  Dyeing  in  Relation  to  Mixed  Fibers. — ^Another  phase  of 
the  dyeing  process  is  in  the  consideration  of  the  relative  affinities  when  one 
dj^estuff  is  applied  in  the  same  bath  sunultaneously  to  two  different  fibers. 
This  question  comes  up  in  a  practical  manner  in  the  dyeing  of  union  goods 
composed  of  wool  and  cotton,  or  of  half-silks  composed  of  silk  and  cotton, 
or  of  gloria  composed  of  wool  and  silk.  A  good  example,  in  this  connection, 
is  the  behavior  of  Curcurmine  S;  this  coloring  matter  is  readily  taken  up 
by  wool  from  an  acid  bath  and  by  cotton  from  a  neutral  bath.  If  both  of 
these  fibers,  however,  are  present  even  in  an  acid  bath,  the  cotton  will  take 
up  the  color  almost  exclusively,  while  the  wool  is  left  practically  undycd. 
This  curious  result  is  to  be  explained  by  the  fact  that  the  cotton  fiber  has 
a  much  greater  affinity  for  this  dyestuff  than  has  wool,  and  this  is  suflficient 
to  almost  ncutrahze  the  action  of  the  dyestuff  on  the  latter  fiber.  Another 
example  is  that  of  Purpuramine;  this  dyestuff  is  a  substantive  coloring 
matter  and  gives  a  rose-rod  color  on  cotton  in  a  neutral  bath.  If,  how- 
ever, wool  is  present  in  the  same  bath  with  the  cotton,  nearly  the  whole 
of  the  coloring  matter  is  taken  up  by  the  wool  and  the  cotton  remains  almost 
white.  Furthermore,  this  same  result  is  obtained  if  cotton  and  silk  are 
dyed  together  in  the  same  bath  with  Purpuramine,  the  silk  being  strongly 
colored,  while,  as  before,  the  cotton  is  scarcely  tinted.  From  this  it  may 
be  seen  that  though  Purpuramine  is  classed  as  a  substantive  or  direct  dye 
for  cotton,  it  has  a  much  greater  affinity  for  the  animal  fibers.  An  example 
of  the  reverse  action  is  that  of  Benzo  Pure  Blue;  this  dyestuff  when  dyed 
in  a  single  bath  on  wool-cotton  or  silk-cotton  material,  is  taken  up  only 
by  the  cotton,  leaving  the  wool  or  the  silk  almost  white. 

Indigo  Carmine  dyes  both  wool  and  silk  in  an  acid  bath  when  either 
fiber  separately  is  used;    but  when  both  of  these  fibers  are  dyed  simul- 


600  THEORY   OF   DYEING 

taneously  in  the  same  bath  the  wool  takes  up  nearly  all  of  the  dyestuff 
and  the  silk  is  onty  sUghtly  tinted.  Thase  examples  are  sufficient  to  show 
the  complex  nature  of  the  relations  between  one  dyestuff  and  two  fibers, 
and  the  influence  the  presence  of  one  fiber  has  on  the  affinity  of  a  dyestuff 
for  another  fiber. 

We  may  extend  the  consideration  of  these  relations  still  further  to  the 
distribution  of  two  dyestuffs  between  two  or  more  fibers.  As  an  example 
of  this  may  be  given  the  dyeing  of  a  mixture  of  wool  and  cotton  in  a  single 
bath  wdth  Curcurmine  S  and  Purpuramine.  In  this  case,  the  cotton  will 
be  dyed  yellow  and  the  wool  red.  The  same  result  will  also  be  obtained 
if  a  mixture  of  cotton  and  silk  is  dyed  with  this  combination  of  dyestuffs, 
the  animal  fiber  being  dyed  red  while  the  cotton  is  dyed  yellow.  In  a 
similar  manner,  if  a  mixture  of  Purpuramine  and  Benzo  Pure  Blue  is  used, 
the  cotton  will  be  dj'ed  blue  and  the  animal  fiber  will  be  dyed  red.  If  a 
mixture  of  the  above  three  dyes  is  used,  the  cotton  will  be  dyed  green, 
while  the  animal  fiber  will  be  red.  Of  course,  the  mass  action  of  the  dye- 
stuff  used  as  well  as  that  of  the  fibers  will  also  come  into  play  and  influence 
the  results  more  or  less. 

5.  Different  Factors  in  the  Theory  of  Dyeing.- — In  summing  up  the 
consideration  of  the  theoiy  of  dj-euig,  it  may  be  said  that  the  following 
factors  enter  into  the  question : 

(1)  The  solution  factor,  which  may  be  defined  as  the  difference  existing 
between  the  degi'ee  of  solubility  of  the  coloring  matter  in  water  and  that 
of  its  solubility  in  the  substance  of  the  fiber.  This  might  be  called  the 
"  affinity  "  of  the  dyestuff  for  the  fiber. 

(2)  The  fiber  factor,  depending  on  the  nature  and  condition  of  the 
material  being  dyed. 

(3)  The  dyestuff  factor,  depending  on  the  chemical  nature  of  the  dye- 
stuff  used. 

(4)  The  chemical  factor,  which  includes  any  chemical  reaction  which 
maj'-  occur  between  the  fiber  and  the  dyestuff. 

(5)  The  tem'peratvre  factor,  which  describes  the  effect  of  the  tempera- 
ture of  the  bath  on  the  relations  between  the  dyestuff  and  the  fiber. 

(6)  The  salt  factor,  which  relates  in  a  similar  manner  to  the  effect  of 
the  presence  of  certain  neutral  salts  in  the  bath  on  the  dyeing  process. 

(7)  The  mordant  factor ,  or  the  influence  of  the  presence  of  certain  metal- 
lic compounds  in  the  fiber  on  its  affinity  for  the  d3^estuff, 

(8)  The  capillarity  factor,  a  physical  property  of  the  dye  solution 
which  has  to  do  with  the  force  with  which  the  dyestuff  solution  is  absorbed 
by  the  fiber  mechanically. 

(9)  The  osmosis  factor,  another  physical  relation  between  the  dye 
solution  and  the  fiber,  it  being  the  force  with  which  the  dissolved  dyestuff 
tends  to  pass  through  the  cell-wall  of  the  fiber. 


THEORY  OF  MORDANTING 


601 


(10)  The  concentration  factor,  depending  on  the  strength  or  concentra- 
tion of  the  dyebath  with  reference  to  the  amount  of  dissolved  dyestuff  per 
unit  volume. 

(11)  The  bath  factor,  or  the  ratio  between  the  amount  of  fiber  being 
dyed  and  the  amount  of  dye  liquor. 

(12)  The  surface-tension  factor  existing  between  the  dye  solution  and 
the  colloidal  substance  of  the  fiber. 

(13)  The  dyestuff  mass-action  factor,  being  the  influence  of  the  relative 
amounts  of  two  or  more  dyes  in  the  same  bath. 

(14)  The  j^6er  mass-action  factor,  or  the  influence  of  the  relative  amounts 
of  two  or  more  fibers  in  the  same  bath. 


Fig.  280. — Revolving  Tenter  and  Equalizing  Machine, 

6.  Theory  of  the  Mordanting  Process. — Fibers  which  are  indifferent 
towards  certain  dyes  may  usually  be  so  changed  in  their  properties  by  the 
"use  of  suitable  mordants  as  to  have  their  affinity  towards  these  dyes  so 
increased  that  they  may  be  dyed  thereby.  For  instance,  cotton  has  no 
affinity  of  itself  for  the  basic  or  acid  dyes,  but  if  it  is  saturated  with  an  acid 
mordant  such  as  tannic  acid  or  a  fatty  acid  it  may  then  be  dyed  with 
the  basic  colors ;  or  if  it  is  mordanted  with  a  basic  mordant,  such  as  alumina 
or  sodium  stannate,  then  it  may  be  dyed  with  acid  colors.  Wool  and  silk 
have  no  affinity  for  most  of  the  Alizarine  class  of  dyes,  but  if  these  fibers 
are  mordanted  with  metallic  oxides,  such  as  the  oxides  of  chromium, 
aluminium,  iron,  tin,  etc.,  then  they  maj^  readily  be  dyed  with  AHzarines. 
The  mordanting  of  cotton  with  tannic  acid  or  fatty  acids  is  probably  a 


602  THEORY   OF   DYEING 

purely  mechanical  process;  although  the  proper  fixation  of  these  mor- 
dants in  the  fiber  by  means  of  tartar  emetic  or  alum  is  a  chemical  process. 
The  mordanting  of  the  animal  fibers  with  metallic  salts  is  probably  for 
the  most  part  a  chemical  process,  the  metallic  salts  or  oxide  forming  a 
chemical  compound  with  the  substance  of  the  fiber.  It  is  usually  consid- 
ered in  the  case  of  mordanting  wool,  for  instance,  with  metallic  salts,  that 
the  metal  is  precipitated  in  the  fiber  as  the  oxide  or  hydroxide;  in  certain 
methods  of  printing,  this  may  be  a  fact,  but  in  the  ordinary  processes  of 
mordanting  wool  for  dyeing,  it  cannot  be  considered  that  the  oxide  of  the 
metal  is  directly  precipitated  in  the  fiber.  It  is  possible,  for  instance,  to 
mordant  the  wool  by  boiling  in  a  bath  containing  a  solution  of  alum, 
squeezing,  and  then  passing  through  a  bath  containing  ammonia  water; 
this  would  cause  the  precipitation  of  aluminium  hydrate  on  and  in  the 
fiber  as  an  insoluble  body.  As  an  actual  fact,  however,  the  mordanting  is 
not  done  in  this  manner,  but  is  carried  out  by  boiling  the  wool  with  a  solu- 
tion of  alum  and  tartar,  which  it  cannot  be  presimied  would  lead  to  the 
precipitation  of  almniniuni  hydrate.  A  sunilar  condition  also  holds  in 
the  mordanting  of  wool  with  chrome;  chromium  hydrate  is  a  greenish  blue 
body,  and  if  this  substance  were  precipitated  in  the  fiber  by  the  usual 
methods  of  mordanting,  the  wool  should  have  a  greenish  blue  appearance; 
but  as  a  matter  of  fact  it  has  a  yellow  color,  which  i«  a  certain  indication 
that  chromium  hydrate  has  not  been  precipitated  in  the  fiber.  Indeed, 
it  would  be  difficult  to  explain,  in  a  chemical  manner,  just  how  chromium 
hydrate  could  be  formed  by  boiling  wool  in  a  solution  of  potassium  bichro- 
mate and  tartar  or  lactic  acid,  and  more  so  as  it  is  well  known  that  certain 
organic  bocUes,  such  as  sugar,  glycerol,  organic  acids,  etc.,  prevent  by  their 
presence  the  precipitation  of  chromium  salts. 

In  mordanting  cotton  the  case  is  somewhat  different  for  the  metals 
employed  as  mordants  are  usually  m  the  form  of  basic  salts,  and  the  solu- 
tions of  these  by  great  dilution,  by  long  exposure  to  the  air,  or  by  warming 
may  become  dissociated  and  there  may  be  precipitated  either  the  hydroxide 
of  the  metal  or  a  strongly  basic  salt,  for  example,  in  mordanting  cotton 
with  acetate  of  aluminium  a  hj^drate  or  basic  acetate  is  formed.  This, 
however,  cannot  be  considered  as  "  precipitation  "  in  the  chemical  sense 
of  the  term.  Although  it  may  be  shown  that  when  cotton  is  steeped  in 
a  readily  dissociated  solution  of  aluminium  acetate,  a  portion  of  the 
aluminium  is  withdrawn  from  the  bath,  it  cannot  be  shown,  however,  that 
aluminimn  hydrate  as  such  has  been  precipitated  in  the  fiber.  If  such 
were  the  case,  washing  with  lukewarm  acetic  or  hydrochloric  acid  wouk] 
remove  all  the  hydroxide  from  the  filler  again ;  but  this  does  not  happen, 
which  is  an  indication  that  the  aluminium  nmst  be  fixed  in  the  fiber  in 
some  other  form. 

A  properly  mordanted  fiber  requires  that  the  metallic  compound  with 


CHEMISTRY   OF   MORDANTING  603 

which  the  fiber  is  mordanted  must  be  held  l)y  this  in  such  a  form  and  with 
sufficient  energy  that  the  mordant  cannot  be  removed  by  water  or  even 
by  dilute  acids  or  alkalies.  According  to  Witt's  theory  of  solid  solution, 
the  metallic  mordant  is  dissolved  in  the  solid  fiber.  Another  explanation 
is  that  the  nietallic  salt  may  enter  into  chemical  combination  with  the 
fiber  forming  a  metallo-organic  compound. 

If  wool  is  mordanted  in  a  l)ath  containing  copper  sulphate  and  sulphuric 
acid,  the  blue  color  of  the  liquor  on  boiling  soon  becomes  lessened,  and  the 
wool  is  colored  at  first  yellowish  and  then  canary-green.  After  twenty  or 
thirty  minutes'  boiling  the  bath  becomes  perfectly  clear;  the  copper  has 
been  taken  up  by  the  wool  quantitatively,  and  the  presence  of  copper 
can  no  longer  be  detected  in  the  liquor  by  testing  with  ammonia.  That 
the  copper  is  not  contained  in  the  wool  as  hydrate  is  apparent  by  rea- 
son of  the  p-esence  of  free  sulphuric  acid  in  the  bath;  and  besides,  the 
color  of  copper  hydrate  is  bluish  gray,  while  the  wool  is  of  a  yellowish 
green  color.  This  latter  color  is  similar  to  that  of  the  basic  acetate  of 
copper  and  other  salts  of  copper  with  organic  acids.  This  would  seem  to 
indicate  that  the  wool  had  formed  a  chemical  compound  with  the  copper. 
If  wool  is  boiled  in  a  bath  containing  copper  sulphate  and  tartar,  even  after 
two  hours'  heating,  the  greater  part  of  the  copper  will  still  be  left  in 
the  bath  and  is  not  taken  up  by  the  wool.  It  is  probable  that  the  addition 
of  tartar  in  this  case  hinders  the  reaction  between  the  wool  and  the  copper 
by  changing  the  compound  at  the  moment  of  its  formation  into  copper 
tartrate.  The  same  considerations  naturally  enter  into  the  mordanting 
of  wool  with  alum  and  tartar.  The  use  of  tartar  is  only  reasonable  in  the 
case  of  chrome  mordanting,  for  here  it  acts  as  a  reducing  agent;  also  in 
mordanting  with  ferrous  sulphate,  which  eagerly  takes  up  oxygen  and  pre- 
cipitates the  hydrate,  or  at  least,  a  basic  sulphate,  the  action  of  tartar  is 
useful,  as  it  prevents  the  formation  of  the  oxidized  salt,  and  hence  acts 
in  this  case  also  as  a  reducing  agent.  But  with  copper  sulphate  and  with 
alum  there  is  nothing  to  reduce;  hence  why  use  the  tartar.  As  a  matter 
of  fact,  in  mordanting  with  alum,  better  results  are  obtained  by  the  addition 
of  sulphuric  acid  than  by  the  addition  of  tartar.  It  is  true,  the  bath  is  not 
quantitatively  exhausted,  but  the  wool  takes  up  a  greater  quantity  of  the 
aluminimn  compound  in  a  shorter  time  than  when  tartar  is  used. 

Furthermore,  if  wool  is  mordanted  with  chrome  and  lactic  acid,  the 
bath  at  first  is  yellow,  then  green,  and  finally  colorless,  while  the  wool 
becomes  only  slightly  colored^  in  spite  of  the  fact  that  all  the  chrome  has 
been  taken  up  by  the  fiber.  If  chrominium  hydrate  were  in  the  fiber,  the 
color  of  the  latter  should  be  bluish  green,  and  if  a  salt  of  chromium  oxide  as 
such  were  in  the  fiber,  the  latter  would  be  green.  As  this  is  not  the  case, 
however,  the  chromium  must  be  combined  in  the  fiber  in  some  other  form. 

Even  more  striking  is  the  case  of  wool  mordanted  with  iron;   if  wool 


604  THEORY  OF  DYEING 

is  boiled  with  ferrous  sulphate  and  oxalic  acid,  the  fiber  remains  almost 
white  and  retains  this  color  even  on  drying  in  the  air.  Freshly  precipitated 
ferrous  hydrate  is  generally  at  first  pure  white;  in  a  few  seconds,  however, 
it  becomes  green,  then  dark  green,  black-green,  black,  and  finally  reddish 
brown.  If  ferrous  hydrate  had  been  precipitated  on  the  fiber  it  would 
rapidly  show  this  alteration  in  color ;  but  such  is  not  the  case. 

All  these  facts  appear  to  show  that  in  mordanting  with  metalHc  salts 
the  metal  is  combined  with  the  fiber  in  the  form  of  a  metalloorganic  com- 
pound, and  the  fiber  thus  chemically  changed  then  possesses  the  proper 
affinity  for  dyeing  with  the  mordant  dyes. 

This  explanation  of  the  mordanting  process,  of  course,  is  not  applicable 
to  cases  where  the  mordanting  takes  place  in  two  baths  in  such  a  manner 
that  in  the  first  bath  the  fiber  is  simply  mechanically  impregnated  with 
the  solution  of  a  substance  which  will  yield  a  precipitate  with  a  solution 
of  a  metallic  salt.  When  cotton,  for  example,  in  the  dyeing  of  Turkey  Red, 
is  impregnated  with  Turkey-red  oil,  and  after  drjdng,  is  mordanted  with  a 
solution  of  aluminium  acetate,  there  is  formed  a  sulphoricinoleate  which 
is  precipitated  uniformly  through  the  cotton  fiber  as  an  insoluble  com- 
pound. Furthermore,  in  the  waterproofing  of  cloth,  the  wool  is  first 
treated  with  a  warm  solution  of  a  neutral  soap,  then  squeezed  out  and 
treated  with  a  warm  solution  of  copper  sulphate;  whereby  in  a  similar 
manner,  copper  palmitate  is  formed,  which  is  an  insoluble  body,  and  is  not 
taken  up  by  the  wool  chemically.  To  the  same  class  belongs  the  mordant- 
ing of  cotton  with  tannin  and  antimony;  there  is  at  first  simply  an  impreg- 
nation of  the  cotton  with  the  tannin  solution,  and  secondly  a  treatment 
with  tartar  emetic  which  converts  the  tannin  into  a  difficultly  soluble 
antimony  tannate,  which  is  mechanically  held  by  the  cotton  fiber. 

7.  Experimental.  Exp.  234.  Study  of  the  Factors  in  the  Dyeing  Process. — These 
factors  are:  The^^er,  the  dyestuJJ,  the  water,  and  the  temperature.  In  order  that  dyeing 
may  take  place  it  is  necessary  tliat  the  affinity  of  tlie  dyestuff  for  tlie  fiber  be  greater 
than  its  affinity  for  the  water.  Place  wool  in  a  hot  solution  of  Acid  Green,  and  it  becomes 
dyed  an  intense  color.  Cotton  in  an  acid  solution  of  Orange  II  even  on  prolonged 
boiling  is  scarcely  tinted.  Dye  wool  in  a  boiling  acid  bath  of  Naphthol  Yellow  and  it 
is  well  dyed;  while  in  a  cold  bath  it  is  only  slightly  tinted.  The  affinity  for  the  fiber 
is  greater  at  high  temperatures  than  at  low  temperatures. 

Exp.  235.  Showing  Condition  of  Equilibrium  in  the  Dyebath. — Dye  wool  in  a  bath 
with  4  per  cent  of  Ponceau  and  1  per  cent  puljihuric  acid,  until  the  color  on  the  fiber 
becomes  no  deeper.  Test  bath  for  acidity  with  Congo  Red.  Show  that  acid  is  exhausted 
and  that  considerable  color  is  still  left  in  the  batlj.  Take  a  sample  from  the  skein; 
add  1  per  cent  more  of  acid  and  continue  the  dyeing.  It  will  be  found  that  the  point  of 
equilibrium  is  disturbed  and  that  the  fiber  will  take  up  more  dyestuff. 

Dye  a  skein  of  cotton  with  2  per  cent  of  Benzopurpurin  4B,  and  no  salt  until  color 
on  skein  becomes  no  heavier — a  point  of  equilibrium  in  the  dyeing  has  been  reached. 
Take  a  sample  from  the  skein,  add  20  per  cent  of  salt  to  the  bath  and  continue  the 
dyeing.     It  will  be  found  that  more  color  is  now  taken  up.     The  addition  of  salt  to  the 


EXPERIMENTAL   STUDIES  605 

bath  has  lessened  the  affinity  of  the  dye  for  the  water  and  so  changed  the  conditions  of 
equihbrium. 

Exp.  236.  Difference  in  Affinity  Measures  the  Exhaustion  of  the  Dyebath. — Dye  a 
skein  of  wool  with  1  per  cent  of  Indigo  Extract  and  4  per  cent  of  sulphuric  acid;  the  bath 
is  practically  completely  exhausted.  Dye  another  skein  with  1  per  cent  Patent  Blue  V 
and  4  per  cent  of  sulphuric  acid,  and  the  bath  is  only  slightly  exhausted. 

Exp.  237.  Showing  Effect  of  Difference  in  Affinity  in  Mixed  Colors. — Dye  a  skein  of 
wool  with 

1  per  cent  Fast  Red 

1  per  cent  Fast  Yellow 

1  per  cent  Patent  Blue 

4  per  cent  sulphuric  acid. 

Take  a  sample  of  the  dye  liquor  before  dyeing.  After  dyeing  for  five  minutes  take  a 
sample  from  the  skein  and  also  a  sample  of  the  dye  liquor.  Dye  ten  minutes  longer  and 
take  another  sample  from  the  skein  and  from  the  dye  liquor.     Dye  for  fifteen  minutes 


k 


\  ^'W\ 


Fig.  281.— Double-acting  Gig.     (Curtis  &  Marble.) 

longer  and  take  samples  again.  Show  the  gradual  change  in  color  of  the  skein  and 
the  reverse  change  in  the  color  of  the  solution,  due  to  the  rapid  absorption  of  the  red, 
the  gradual  but  rather  complete  absorption  of  the  yellow  and  the  slow  and  very 
imperfect  absorption  of  the  blue. 

Exp.  238.  Showing  How  the  Mass  Relations  of  the  Fiber  and  the  Water  Affect 
the  Affinity. — Dye  a  skein  of  cotton  in  a  neutral  bath  with  1  per  cent  Purpuramine; 
a  rose-red  color  is  obtained.  Then  dye  a  skein  of  cotton  together  with  one  of  wool 
in  a  neutral  bath  with  1  per  cent  Purpuramine;  it  will  be  found  that  only  .the  wool 
becomes  dyed  while  the  cotton  remains  practically  white.  Furthermore,  dye  a  skein 
of  cotton  together  with  one  of  silk  with  1  per  cent  Purpuramine  in  a  soap  bath;  only 
the  silk  will  be  dyed.  Although  this  dyestuff  is  classed  as  a  substantive  dye  for  cotton, 
in  the  presence  of  animal  fibers,  it  no  longer  dyes  the  cotton. 

Dye  a  skein  of  wool  in  a  bath  with  1  per  cent  Benzo  Pure  Blue,  also  dye  a  skein  of 
silk  m  the  same  maimer.     Now  dye  wool-cotton  and  silk-cotton  with  this  dye,  when  it 


606  THEORY  OF  DYEING 

will  be  found  that  the  cotton  only  will  have  become  dyed,  leaving  the  animal  fibers 
white. 

Dye  a  skein  of  silk  in  an  acid  bath  with  1  per  cent  Indigo  Carmine;  it  gives  a  fairly 
heavy  shade.  Now  dye  a  skein  of  wool-silk  in  a  similar  manner,  and  it  will  be  found 
that  the  wool  dyes  heavily,  while  the  silk  is  only  tinted. 

Dye  a  skein  of  wool-cotton  in  a  bath  with  a  mixture  of  1  per  cent  Curcurmine  S  and 
1  per  cent  Purpuramine;  the  cotton  will  be  dyed  yellow  and  the  wool  red.  Repeat 
using  a  skein  of  cotton-silk,  when  the  cotton  will  come  out  yellow  and  the  silk  red. 
Dye  another  ?kein  of  wool-cotton  with  a  mi.xture  of  1  per  cent  Purpuramine  and  1  per 
cent  Benzo  Pure  Blue,  when  the  cotton  is  dyed  blue  and  the  wool  red.  Then  dye  a 
skein  of  wool-cotton  with  a  mixture  of  1  per  cent  Curcurmine  S,  1  per  cent  Purpuramine, 
and  1  per  cent  Benzo  Pure  Blue;  the  cotton  will  be  dyed  green  and  the  wool  red. 


CHAPTER   XXVI 
TESTING  THE  FASTNESS  OF  COLORS 

1.  Fastness  of  Dyes. — In  Cliapter  IX,  ])ricf  methods  have  already 
been  given  for  the  testing  of  dyed  colors  to  various  agencies.  The  present 
chapter  is  intended  to  be  a  more  extended  discussion  of  this  subject. 

By  the  '*  fastness  "  of  a  dye  is  meant  its  resistance  to  the  action  of 
various  agencies  to  change  it  in  color  or  appearance.*  The  fastness  of 
dyes  differs  very  widely  even  among  the  same  class;  some  acid  dyes,  for 
instance,  are  very  fast  while  others  are  fugitive;  and  the  same  is  true  in 
general  of  the  basic  and  substantive  dyes.  The  mordant  dyes  are  to  be 
regarded  as  having  the  greatest  fastness  when  taken  as  a  class;  and  the 
basic  dyes,  as  a  class,  are  probably  the  most  fugitive.  Again,  dyes  may  be 
fast  to  one  agency  and  not  to  others;  for  instance,  Thioflavin  T  dyed  on 
cotton  is  very  fast  to  washing  and  to  fulling,  but  not  at  all  fast  to  light,  f 
Further,  a  dye  may  be  fast  on  one  fiber  and  not  on  another;  and  may  be 

*  The  fastness  of  a  dye  is  more  or  less  a  relative  term,  as  no  color  is  absolutely  fast 
to  all  agencies,  therefore  fastness  becomes  a  matter  of  comparison  with  some  standard 
which  represents  a  satisfactory  and  high  degree  of  resistance  to  change.  Further- 
more, fastness  is  a  rather  variable  term  and  may  be  differently  interpreted  depending 
upon  conditions.  For  example,  when  speaking  of  fulling  we  may  have  hot  acid  fulling 
on  the  one  hand,  as  in  the  manufacture  of  hat  felts;  or  soap  and  alkali  fulling  on  the 
other  hand,  as  in  the  finishing  of  flannels  and  buckskins,  or  in  the  more  severe  fulling  of 
heavy  meltons  and  military  cloths;  furthermore  we  may  have  very  light  fulling  with 
plain  hot  water,  as  in  the  finishing  of  certain  kinds  of  ladies'  dress  goods  and  worsted 
suitings.  It  may  readily  be  understood  that  a  dyestuff  may  be  quite  fast  to 
water  or  acid  fulling  and  yet  quite  useless  for  soap  and  alkali  fulling.  Or  a  dyestuff  in 
light  shades  may  satisfactorily  withstand  the  fulling  operation,  yet  bleed  badly  in  heavy 
shades.  Fre  uently  the  character  and  cleanliness  of  the  dyed  material  and  the  method 
of  dyeing  may  have  considerable  influence  on  the  fastness  to  fulling,  as  well  as  the 
make-up  of  the  liquor  used  in  fulling.  Therefore,  it  may  be  seen  that  no  general  state- 
ment of  the  fastness  of  a  certain  dye  in  this  respect  could  be  properly  made 
without  some  understanding  of  the  modifying  conditions. 

t  Benzopurpurin,  for  instance,  and  other  substantive  dyes,  when  dyed  on  wool, 
are  much  faster  to  light  and  washing  than  when  dyed  on  cotton.  On  the  other 
hand.  Methylene  Blue  when  dyed  on  cotton  with  a  tannin-antimony  mordant, 
is  much  faster  than  when  dyed  directly  on  wool.  In  fact  the  basic  colors  are 
all  faster  to  light  when  dyed  on  a  tannin-antimony  mordant  than  when  applied  in  con- 
nection with  other  mordants. 

607 


GU8 


TESTING   THE   FASTNESS   OF   COLORS 


fast  when  dyed  by  one  method  (or  mordant)  and  not  fast  when  dyed  by 
another  method  (or  mordant).* 

2.  Testing  Fastness  of  Colors  Dyed  on  Wool. — The  chief  agencies  to 
which  colors  on  wool  arc  tested,  togeth(>r  with  the  means  of  so  testing  them, 
are  as  follows: 

(1)  Fastness  to  Light. — A  sample  of  the  dyed  wool  is  placed  in  a  suit- 
able frame  in  such  a  manner  that  only  a  part  is  exposed.  The  frame  is 
then  placed  in  such  a  position  that  it  receives  as  strong  sunlight  as  possible, 
but  is  shielded  from  exposure  to -the  atmosphere  by  glass.  A  window  with 
southern  exposure  is  a  good  location  in  which  to  hang  the  frame  contain- 
ing the  samples,  t     At  the  end  of  one  week's  exposure  the  samples  are 

*  It  must  be  borne  in  mind  in  judKing  the  value  of  a  dye  with  respect  to  its  quali- 
ties of  fastness  that  the  degrees  of  fastness  to  different  agencies  are  not  equally  impor- 
tant under  different  conditions.  The  kinds  of  fastne.ss  to  be  sought  for  depend  on  the 
use  and  manner  of  wear  to  which  the  dyed  material  is  to  be  subjected.  For  instance, 
in  choosing  a  dyestuff  for  application  to  hosiery  good  fastness  to  light  is  not  essential 
whereas  proper  fastness  to  washing  and  perspiration  is  very  necessary.  On  the  other 
h  nd,  in  selecting  dj^estuffs  for  use  with  carpet  yarns,  attention  should  be  given  to  the 
fastness  of  the  color  to  crocking  and  light,  while  the  fastness  to  washing  and 
perspiration  may  be  neglected. 

t  The  fading  of  colors  in  light  depends  to  a  very  large  degree  on  the  (juality  and 
intensity  of  the  light  to  which  they  are  subjected.     Bright  direct  sunlight  has  a  strong 

fading  effect,  whereas  with  indirect  reflected  light 
the  degree  of  fading  may  be  quite  small.  A  dyed 
fabric,  for  example,  exposed  to  the  effect  of  direct 
sunlight  in  a  window  may  show  a  distinct  fading  in 
a  few  days,  while  the  same  fabric  at  the  inner  part 
of  an  ordinary  dwelling-room  with  indirect  light 
from  a  north  exposure  may  not  show  an  equal 
fading  until  the  lapse  of  several  months  or  a  year. 

The  effect  of  most  artificial  light  on  colors  is  far 
less  than  sunlight.  Gas,  oil  lamps,  and  incan- 
descent electric  lighting  have  but  little  fading 
effect  on  most  colors.  The  electric  arc  lamp  and 
the  ultra-violet  lamp,  however,  if  in  close  proximity 
to  the  color,  will  cau.se  a  rapid  fading  Ultra-violet 
light,  in  fact,  may  be  employed  for  testing  the 
comparative  light  fastness  of  dyed  colors,  as  close 
exposure  of  the  sample  to  this  light  will  give  results 
in  a  much  shorter  time  than  testing  in  sunlight.  A 
few  hours'  exposure  under  the  ultra-violet  lamp  will 
be  equivalent,  perhaps,  to  a  week's  exposure  to 
ordinary  direct  sunlight. 

The  color  of  the  light  to  which  the  dyed  material 

is  exposed  also  has  much  influence  on  its  fading. 

Dyed  colors  exposed  to  the  action  of  red  light  show 

practically  no  fading  at  all;  exposed  to  yellow  light 

the  fading  is  slight,  while  exposure  to  blue  light  shows  the  greatest  fading  effect.     It 

is  probably  the  ultra-violet  or  actinic  rays  present  in  light  which  cause  the  breaking 

down  of  the  dyestuff  and  the  consequent  fading  of  the  color. 


Fig.  282. —  Quartz  Ultra-Violet 
Lamp  for  Testing  Fastness  of 
Colors  to  Light.     (Hanovia.) 


FASTNESS   TO    LIGHT  609 

examined  and  note  made  of  those  which  show  any  appreciable  facUng; 
these  are  to  be  classified  as  not  fast.  At  the  end  of  the  second  week 
another  examination  is  made  and  those  samples  noted  which  show  an  appre- 
ciable fading;  these  are  to  be  classified  as  fairly  fast.  At  the  end  of  four 
weeks  the  samples  are  once  more  examined  and  the  colors  facHng  in  this 
period  are  noted  and  classified  as  fast.*  The  samples  which  show  no  fading 
at  the  end  of  four  weeks  are  classified  as  very  fast.f 

Dye  test  skeins  of  woolen  yarn  with  2  per  cent  each  of  the  ten  following 
dyes,  and  test  samples  of  the  colors  for  fastness  to  light  in  the  manner 
above  described. 

1.  Magenta  (in  neutral  bath). 

2.  Eosin  (in  acetic  acid  bath). 

3.  Acid  Violet  (in  usual  acid  bath). 

4.  Tartrazine  (in  usual  acid  bath). 

5.  Patent  Blue  V  (in  usual  acid  bath). 

6.  Light  Green  SF  (in  usual  acid  bath). 

7.  Diamine  Scarlet  3B  (ammonium  acetate  loath) 

8.  Cloth  Red  GA  (acid  bath  and  after-chromed). 

9.  Alizarine  Red  WS  (on  alum  mordant). 
10.  Alizarine  Blue  NG  (on  chrome  mordant). 

In  making  the  test  for  fastness  to  light,  as  the  nature  and  amount  of 
sunlight  obtainable  day  by  day  is  very  variable,!  a  more  accurate  method  is 
to  expose,  with  the  samples  to  be  tested,  control  samples  of  ch^es  repre- 
senting the  four  degrees  of  fastness  to  light,  such  as: 

1.  Very  fast.  Alizarine  Red  WS  (on  a  chrome  mordant). 

2.  Fast,  Lanacyl  Blue  R  (m  usual  acid  bath). 

*  The  fastness  to  light  of  some  dyestuffs  on  wool  and  cotton  may  be  materially 
improved  by  an  after-treatment  of  the  dyed  color  with  bluestone  or  copper  sulphate 
(see  page  281).  The  exact  cause  for  this  increase  in  light  fastness  is  not  definitely 
known.  By  some  it  is  supposed  that  the  cells  of  the  fiber  become  coated  with  a  film  of 
copper  salt  which  acts  as  a  protective  light  filter  in  cutting  off  the  actinic  rays.  This 
theory,  however,  has  little  or  no  experimental  evidence  in  its  favor.  Another  explana- 
tion is  that  the  copper  forms  a  combination  with  the  dyestuff,  and  the  color-lake  so 
produced  has  more  stability  towards  light.  This,  however,  is  also  a  mere  theory  with 
no  known  data  in  its  support. 

t  According  to  the  calculations  of  Sir  Wm.  Abney  the  fading  power  of  one  month's 
direct  sunshine  on  a  color  is  equal  to  a  hundred  years  of  ordinary  diffused  daylight  in  a 
room. 

t  Other  conditions  besides  the  light  also  effect  the  fading  of  colors.  It  has  been 
shown  that  dyed  colors  exposed  in  a  vacuum  fade  very  much  less  than  the  same  colors 
exposed  in  air  under  the  same  conditions  of  light.  Colors  exposed  in  moist  air  fade  a 
great  deal  more  than  the  same  colors  similarly  exposed  in  dry  air.  Furthermore  colors 
do  not  fade  to  the  same  extent  under  the  influence  of  differently  colored  rays  of  light. 
Violet  and  blue  rays  appear  to  have  the  strongest  action,  whereas  the  red  rays 
are  weakest.  The  j^ellow  and  green  rays  have  an  effect  between  these  two  ex- 
tremes. 


610  TESTING   THE   FASTNESS  OF   COLORS 

3.  Fairly  fast,  Alkali  Blue  R  fin  neutral  bath  and  developed  with  acid). 

4.  Eosin  (in  weak  acetic  acid  bath). 

The  samples  are  examined  from  time  to  time,  and  those  colors  fading 
in  the  same  periods  as  the  control  samples  are  noted  and  classified  accord- 
ingly. In  this  manner  the  variable  effect  due  to  the  inconstant  degi-ee  of 
light  is  eliminated,  and  the  tests  made  comparable  to  certain  fixed  stand- 
ards. 

Another  Ught  relation  with  respect  to  dyed  colors  to  l>e  observed  is 
the  change  in  tone  which  sometimes  occurs  when  the  color  is  A-iewed  in 
artificial  light  as  compared  with  the  tone  as  seen  in  daylight.  The  color 
of  many  dyes  changes  quite  considerably  under  these  conditions,  and  fre- 
quently this  is  very  undesirable  when  the  color  is  applied  to  fabrics  used 
for  evening  wear.  The  colors  on  different  parts  of  a  suit  or  gown  may 
match  satisfactorily  in  daylight,  but  when  seen  in  artificial  light  objection- 
able differences  may  be  apparent.  This  is  especially  to  be  noticed  in  the 
case  of  blacks  and  blues,  which  under  the  influence  of  artificial  light  may 
change  to  prune  or  violet  tones.  These  changes  in  tone  were  more  notice- 
able formerly  than  at  present  owing  to  improvements  in  artificial  illumina- 
tion whereby  the  light  now  used  (tungsten  filaments)  has  more  the  color 
balance  of  daj-light  than  the  former  very  yellow  gas  and  oil  lighting. 

(2)  Fastness  to  Washing. — This  test  is  to  represent  the  fastness  of  a  dj'e 
to  washing  or  scouring  with  soap  and  water.  Dyed  woolen  material  of 
almost  any  character  should  be  capable  of  standing  a  more  or  less  severe 
scouring,  as  such  an  operation  is  alwaj^s  necessarj^  in  the  cleansing  and 
finishing  of  woolen  goods  in  the  course  of  their  manufacture.  Material 
dyed  as  loose  stock  must  afterwards  stand  a  rather  severe  scouring  in  order 
to  remove  the  oils  added  for  purposes  of  spinning;  yarn-dyed  material 
also  accimiulates  considerable  grease  and  dirt  in  handling  and  wea\4ng  and 
must  also  be  scoured.*  Goods  dyed  in  the  piece  are  usually  scoured  before 
dyeing;  hence  colors  in  this  latter  case  need  not  be  especially  fast  to 
scouring,  unless  the  character  of  the  goods  requires  them  to  be  subsequently 
scoured  either  in  manufacturing  or  in  wearing.  The  best  manner  of 
conducting  the  washing  or  scouring  test  is  as  follows :  Plait  together  a  few 
strands  of  the  dyed  test  skein  with  an  ecjual  portion  of  wliite  wool  yarn  and 
white  cotton  yarn.  Scour  tliis  sample  for  ten  minutes  in  a  miniature 
scouring  bath  (about  50  cc.)  containing  5  grams  of  soap  per  Uter  at  a 
temperature  of  140°  F.  Squeeze,  wash  off  in  fresh  water,  and  dry.  Note 
if  the  dye  tints  the  soap  solution,  and  if  it  tints  either  the  white  wool  or 
the  white  cotton.  The  latter  is  used  in  the  test  as  cotton  threads  are  fre- 
quently employed  in  the  weaving  of  woolen  goods.     Some  dyes  may  tint 

*  Dyed  cotton  j'arns  intended  to  be  used  as  lists  for  raw  silk  goods  which  are  sub- 
sequently boiled  off  in  the  piece,  must  possess  a  very  high  degree  of  fastness  to  washing; 
about  the  only  colors  which  are  suitable  for  this  purpose  are  some  of  the  sulphur  dyes. 


FASTNESS   TO   WASHING 


611 


the  soap  solution  without  staining  the  white  yarns,  but  this  may  result  in 
the  staining  of  other  colors,  hence  such  dyes  cannot  be  considered  fast: 
again,  some  dyes  may  stain  the  white  wool,  and  not  the  white  cotton,  or 
vice  versa;  in  either  case,  the  color  must  be  classed  as  not  fast.  As  to 
degrees  of  fastness,  an  arbitrary  classification  may  be  made  as  follows: 

1.  Fast ;  does  not  tint  the  soap  Uquor,  nor  either  of  the  white  yarns. 

2.  Fairly  fast ;  tints  the  soap  liquor,  but  not  the  white  yarns. 

3.  Not  fast;  tints  either  of  the  white  yarns;  the  soap  liquor  may  or 
may  not  be  tinted. 

Make  up  plaited  test  samples  from  each  of  the  ten  colors  given  above, 
and  test  them  as  to  fastness  to  washing  in  the  manner  described;  it  is  need- 
less to  add  that  a  fresh  portion  of  soap  liquor  must  be  used  for  each  sample 
tested. 


^, 


m$^^ 


Fig.  283. — Double-oylinder  Gessner  Gig  with  Reverse  Motion.     (Curtis  &  Marble.) 

(3)  Fastness  to  Fulling. — This  is  also  called  milHng,  and  refers  to  th.c 
process  whereby  woolen  cloth  is  felted  more  or  less  in  order  to  make  a 
denser  fabric  or  to  otherwise  finish  the  goods.  The  feltmg  is  carried  out  i:i 
fulling  mills  or  stocks,  in  which  the  material  is  saturated  usually  with  a;^. 
alkaline  soap  liquor  and  then  rubbed  and  squeezed  together  until  the  desircc' 
degree  of  felting  is  obtained.  The  process  of  fulling  is  a  verj^  severe  test 
on  colors,  and  the  mordant  dyes  are  about  the  only  ones  which  will  stand 
a  hard  fulling;  there  are,  however,  certain  acid  and  substantive  colors  on 
wool  which  will  stand  a  fair  degree  of  fulling.  The  basic  dyes  will  not 
stand  fulHng.* 

*  Change  in  tone  of  the  color  is  generally  due  to  the  action  of  the  alkali,  .but  if  the 
color  loses  in  strength  it  indicates  that  the  dj'estuff  is  either  dissolved  or  is  rubbed  oh 
the  fiber.  In  the  case  of  Alkali  Blue,  it  is  decolorized,  but  the  color  is  restored  on  treat- 
ment with  acids.  Bleeding  in  the  fulling  process  may  be  due  to  superficial  fi.xation  of 
the  dyestuff  which  is  easUy  rubbed  off,  or  it  maj'  be  due  to  actual  solution  of  the  dye- 
stuff  in  the  fulling  liquor.     Goods  intended  for  fulling  should  always  be  thoroughly 


612  TESTING   THE   FASTNESS  OF   COLORS 

The  fulling  test  may  best  be  carried  out  as  follows:  Make  a  loose 
plait  containing  several  strands  of  the  dj^ed  j^arn  mixed  with  strands  of 
white  woolen  and  cotton  yarns,  and  treat  with  a  solution  containing  10 
grams  of  soap  and  2  grams  of  soda  ash  per  liter  at  140°  F.  Soak  the  sample 
in  this  solution  and  rub  between  two  pieces  of  board  until  the  wool  yarns 
are  well  felted  together.  Then  wash  in  fresh  water,  and  dry.  Note  if  the 
color  has  lost  in  intensity  or  if  it  has  bled  into  either  the  white  wool  or 
cotton.  In  such  case  the  dj^e  cannot  be  considered  fast  to  fulling.  Accord- 
ing to  the  degree  of  bleeding,  the  color  may  be  classed  as  not  fast  or  as 
fairly  fast.  If  the  dj-e  neither  loses  in  color  nor  bleeds,  it  may  be  classed  as 
fast.  Prepare  test  samples  from  each  of  the  ten  dyes  given  and  test  them 
in  manner  described  for  fastness  to  fulHng. 

(4)  Fastness  to  Rubbing. — This  is  also  termed  "  crocking,"  and  refers 
to  whether  or  not  the  dye  will  mechanically  rub  off,  and  thus  stain  white 
or  other  colors  with  which  it  may  come  in  contact.  Heavy  shades  are 
more  apt  to  rub  than  light  shades.  As  a  rule,  the  acid  and  substantive 
dj^es  on  wool  do  not  rub;  the  basic  dj'es  frequently  show  this  defect; 
heavy  shades  of  mordant  (or  pigment  dyes  in  general)  will  frequently  rub 
off  to  some  exent  whereas  lighter  shades  do  not.*  Hea\y  shades  of  Indigo 
(a  pigment  dye),  for  instance,  mb  off  considerably,  whereas  the  Chrome 
Blues  producing  the  same  shades  are  very  fast  to  rubbing. f  The  test  for 
fastness  to  rubbmg  is  easily  and  sun]:)ly  carried  out  by  rubbing  a  portion 

washed  after  dyeing  in  order  to  remove  all  trace  of  adhering  dye  liquor.  Colors  will 
sometimes  bleed  if  allowed  to  lie  for  a  long  time  in  a  wet  state  which  would  otherwise 
be  satisfactory  if  the  fulling  is  not  prolonged  unduly.  As  fulling  is  a  very  variable 
operation,  both  in  character  and  severity,  depending  on  the  nature  of  the  goods,  fast- 
ness to  fulling  must  be  described  advisedly  and  with  reference  to  the  particular  con- 
ditions to  be  met  with.  The  method  of  testing  as  herewith  described  will  furnish  a 
general  statement  of  relative  fastness  to  fulling;  but  in  the  practical  application  of  dye- 
stuffs,  the  fulling  test  should  be  carried  out  under  conditions  simulating  those  the  dyed 
goods  will  meet  with  in  practice.  In  this  waj'  the  fastness  can  be  judged  with  reference 
to  the  particular  purpose  in  hand.  In  fact,  whenever  the  question  of  using  a  new  and 
untried  dyestuff  is  under  consideration,  it  is  best  to  send  a  dyed  sample  through  the 
entire  process  of  manufacture,  and  thus  judge  at  first  hand  of  the  possible  effect  on  the 
color. 

*  The  colors  produced  in  garment  dyeing  are  usually  less  fast  to  rubbing  than  those 
produced  in  ordinary  dyeing,  owing  to  various  limitations  imposed  by  the  dyeing 
process,  and  also  on  account  of  absence  of  finishing  treatment. 

t  Dyed  colors  may  at  times  show  the  defect  of  crocking  when  the  fault  is  not  pri- 
marily with  the  dyestuff.  Dirt}'  and  badly  scoured  goods,  the  use  of  hard  water  and 
imperfect  methods  of  dj'eing  and  washing  will  often  cause  a  color  to  crock  which  would 
otherwise  be  perfectly  fast  in  this  respect.  Washing  woolen  goods  with  fuller's  earth 
will  frequently  remedy  crocking  by  removing  the  imperfectly  fixed  dyestuff  from  the 
fiber.  A  slight  sizing  on  cotton  goods  at  times  gives  the  same  result.  Union  goods, 
where  the  cotton  warp  is  dj^ed  with  basic  colors,  will  often  crock.  This  defect  may 
usually  be  remedied  bj-  washing  with  soap  bark  (Quillaya)  or  with  a  little  glue. 


FASTNESS  TO   WATER  613 

of  the  dyed  sample  on  a  piece  of  white  calico,  and  noting  if  a  stain  is  left.* 
Test  the  ten  dyed  samples  in  this  manner,  and  classify  as  fast  or  not  fast 
to  rubbing. 

(5)  Fastness  to  Wate7\ — The  object  of  this  is  to  discover  if  the  dye 
will  bleed  into  white  yarn  on  boiling  in  water  or  on  prolonged  steeping  in 
cold  water. t  Test  as  follows:  (a)  Plait  several  strands  of  the  dyed  yarn 
with  some  white  wool  and  white  cotton  yarns,  and  boil  with  \Vater  for  one 
hour.  Squeeze  and  dry.  Note  if  the  white  yarns  become  stained,  (b) 
Use  another  plaited  sample  as  above,  and  steep  in  cold  water  for  twelve 
hours.  Note  if  the  white  yarns  become  stained.  If  the  dye  does  not 
bleed  at  all  in  boiling  water  it  may  be  classed  as  fast;  if  it  bleeds  slightly 
in  boihng  water,  but  not  in  cold  water,  it  is  fairly  fast;  and  if  it  bleeds  in 
the  cold  water  test,  it  is  not  fast.  Carry  out  tests  on  the  ten  dyed  samples 
in  the  manner  described,  and  classify  these  dyes  with  respect  to  their 
fastness  to  water. 

(6)  Fastness  to  Weather. — By  this  is  meant  fastness  to  the  varying  con- 
ditions of  exposure  to  the  atmosphere,  such  as  alternate  wetting  by  rain  or 
dew  and  drying  by  the  heat  of  the  sun,  etc.  J  The  best  and  most  practical 
method  of  applying  this  test  is  to  expose  a  sample  of  the  dj^ed  material 
to  the  action  of  the  weather  for  two  weeks  or  more.     But  the  results  may 

*  If  a  very  severe  rubbing  test  is  desired  the  dyed  sample  should  be  rubbed  on  a  damp 
piece  of  white  calico. 

t  Fastness  to  water  is  required  of  colors  on  garment  materials  liable  to  be  wet  by 
rain.  It  is  also  required  of  colors  while  the  goods  are  passing  through  certain  manu- 
facturing and  finishing  operations ;  for  instance,  colored  yarns  intended  for  fancy  weav- 
ing must  not  bleed  when  sized,  as  the  other  yarns  may  be  stained;  also  colored  woolen 
goods  must  not  bleed  in  steaming  when  drops  of  hot  water  fall;  light-weight  dress 
goods  are  usually  subjected  to  a  slight  fulling  in  hot  water  and  the  colors  must  not  bleed; 
also  suitings  are  often  put  through  a  potting  (steaming)  process  where  they  are  also 
treated  with  water  and  under  these  conditions  of  wetting  the  colors  should  not  bleed. 
Colored  yarns  will  frequently  show  bleeding  into  white  when  the  two  are  woven  together 
in  close  contact,  though  no  bleeding  might  be  apparent  if  the  yarns  are  treated  with 
water  but  not  in  actual  contact  with  one  another.  Soap  and  alkaline  residues  in  the 
goods  may  also  cause  bleeding  in  water  with  colors  that  would  otherwise  be  fast.  By 
after-treating  the  dyed  material  with  alum,  it  is  sometimes  possible  to  prevent  the  bleed- 
ing of  a  color  in  water.  Also  in  water  fulling  (or  in  potting)  bleeding  may  be  prevented 
by  slightly  acidulating  the  water. 

X  This  effect  is  far  different  from  that  of  sunlight  alone;  in  fact,  continued  weather 
exposure  is,  perhaps,  the  severest  treatment  to  which  colors  may  be  rationally  exposed. 
A  dyestuff  may  have  excellent  fastness  to  light  and  be  eminently  suitable  for  curtains 
and  window  shades,  and  yet  be  useless  for  the  dyeing  of  awning  material  or  flags.  It 
may  be  said  that  as  far  as  organic  dyes  are  concerned,  whether  of  natural  or  of  syn- 
thetic origin,  all  are  eventually  destroyed  by  continued  exposure  to  weather  conditions. 
The  mineral  pigment  dyes  alone  will  retain  their  color  under  such  treatment,  and  even 
many  of  these  suffer  considerable  deterioration  owing  to  chemical  changes  brought 
about  by  the  oxidizing  influence  of  sunlight  and  rain. 


614  TESTING  THE  FASTNESS  OF  COLORS 

be  approximately  represented  by  the  following  test:  (a)  Steep  a  sample 
of  the  dj^etl  yarn  in  a  solution  containing  2  parts  of  hydrogen  peroxide 
(10-volume  strength)  and  10  parts  of  water  for  one  hour.  Dry  and  com- 
pare with  the  original  sample.  (6)  Repeat  the  test,  using  a  hydrogen 
peroxide  solution  of  10-volume  strength  undiluted  with  water;  steep  for 
one  hour,  and  on  drying  compare  with  the  original  sample.  If  no  altera- 
tion in  the*  color  is  appreciable  after  test  (6),  the  dye  may  be  classed  as 
fast;  if  test  (6)  shows  an  alteration  in  the  color,  but  not  test  (a),  the  dye 
may  be  classed  as  fairly  fast;  if  test  (a)  shows  an  appreciable  alteration, 
the  dye  is  not  fast.  By  combining  this  test  with  the  one  to  sunlight,  a  fair 
idea  of  the  fastness  of  the  dye  to  weather  exposure  may  be  gained.  It  is 
probable  that  in  the  wetting  of  material  by  rain  or  dew  and  subsequent 
evaporation  by  the  heat  of  the  sun,  a  trace  of  hydrogen  peroxide  is  formed 
which  has  a  bleaching  action  on  colors. 

(7)  Fastness  to  Acids  and  Carbonizing.- — In  many  cases  dyed  woolen 
materials  are  treated  with  moderately  strong  solutions  of  acids  and  dried 
in  order  to  decompose  any  particles  of  vegetable  matter  which  may  be 
present;  tliis  process  is  known  as  carbonizing.  To  test  the  fastness  of  a 
dyestuff  to  this  operation,  proceed  as  follows:  Inmierse  a  sample  of  the 
dyed  j'arn  in  a  solution  of  sulphuric  acid  of  4°  Tw.  at  175°  F.  for  half  an 
hour;  squeeze  and  without  washing  dry  in  a  hot-air  flue.  Then  wash  out 
and  neutralize  the  acid  in  a  bath  containing  about  1  gram  of  soda  ash  to 
100  cc.  of  water;  finally  rinse  well,  and  dry.*  Compare  with  the  original 
color,  and  note  if  the  carbonizing  process  has  altered  the  shade  in  any 
manner.  According  to  the  extent  of  change  in  the  shade  classify  as  not 
fast,  fairly  fast,  and  fast.  Test  in  this  manner  each  of  the  ten  dyed  sam- 
ples, t 

(8)  Fastness  to  Perspiration. — This  is  required  of  all  dyed  clothing 
material  that  is  worn  next  the  skin ;  also  of  material  used  for  making  horse- 
blankets,  etc.  The  most  reliable  test  is  to  wear  a  sample  of  the  dyed  wool 
in  such  a  manner  as  to  expose  it  to  the  action  of  perspiration. |     This 

*  Sometimes  in  carbonizing  the  dyed  color  may  undergo  an  alteration  in  tone  due 
to  the  action  of  the  acid,  but  the  original  color  is  restored  when  the  goods  are  properly 
neutralized  with  soda. 

t  Sometimes  when  dyed  goods  are  stored  in  warehouses  or  shops  for  a  long  period 
the  colors  may  suffer  some  change.  As  the  goods  are  usually  sufficiently  protected  from 
light  the  change  is  usually  due  to  the  action  of  acid  gases  in  the  air.  These  acids  may 
arise  from  the  products  of  combustion  (gas  lights)  or  from  coal  gas.  In  some  cases, 
however,  the  alteration  in  shade  may  be  due  to  an  oxidation  of  the  dyestuff .  Sulphur 
colors  are  often  liable  to  exhibit  this  effect. 

X  The  action  of  perspiration  is,  perhaps,  chiefly  due  to  the  effect  of  certain  weak 
organic  acids,  such  as  acetic  and  lactic,  but  apparently  other  influences  also  come  into 
operation,  so  that  the  only  reliable  test  is  to  actually  wear  the  sample  so  that  it  comes 
into  direct  contact  with  perspiration.  A  good  practical  test  is  to  put  the  sample  under 
the  saddle  cloth  of  a  horse. 


FASTNESS   TO   ALKALI   AND   STOVING  615 

action,  however,  may  be  well  represented  by  the  following  test:  Plait  a 
sample  of  the  dyed  yarn  with  white  woolen  and  cotton  j^arns,  and  unmerse 
for  one  hour  in  a  solution  of  lactic  acid  of  4°  Tw.  at  100°  F.  Squeeze, 
and  dry  without  washing  in  the  air.  Note  if  the  color  has  suffered  any 
alteration  in  shade  or  if  it  has  stained  either  of  the  white  yarns.  According 
to  the  extent  of  change  or  staining  classify  as  not  fast,  fairly  fast,  or  fast.* 

(9)  Fastness  to  Alkali. — In  order  to  remove  the  fatty  matters  from 
woolen  goods  a  washing  with  dilute  soda  ash  solution  is  frequently  given. 
This  is  especially  true  of  material  which  is  fulled.  To  discover  if  the  color 
will  withstand  such  a  treatment,  a  test  is  made  as  follows:  A  sample  of 
the  dyed  yarn  is  plaited  with  white  wool  and  white  cotton,  and  steeped  for 
one  hour  in  a  solution  of  soda  ash  of  3°  Tw.  at  120°  F.,  then  washed  in 
fresh  water  and  dried.  Note  if  the  color  suffers  any  alteration,  or  if  either 
of  the  white  yarns  is  stained.  According  to  the  extent  of  change  in  color 
or  staining  the  dye  is  to  be  classified  as  not  fast,  fairly  fast,  or  fast. 

(10)  Fastness  to  Lime  or  Street  Dust. — Dyed  clothing  materials  such  as 
ladies'  dress  goods  and  gentlemen's  suitings  have  to  withstand  the  action 
of  street  dust,  mud,  etc.  This  action  is  best  represented  by  a  test  with 
lime  as  follows :  Spot  a  sample  of  the  dyed  yarn  with  a  solution  containing 
20  grams  quicklime  and  10  cc.  ammonia  per  liter.  Allow  this  to  dry  on 
the  material,  and  then  brush  off.  Note  if  the  color  has  suffered  any  alter- 
ation. 

(11)  Fastness  to  Sulphuring  or  Stoning. — In  some  cases  dyed  woolen 
yarn  is  woven  together  with  white  and  the  cloth  subsequently  bleached 
by  the  action  of  sulphurous  acid  gas.  To  discover  if  the  dye  will  with- 
stand the  action  of  the  sulphurous  acid  test  as  follows :  Take  a  small  sample 
of  the  dyed  yarn,  moisten  it  with  water,  and  hang  it  for  six  hours  in  a  closed 

*  Our  knowledge  concerning  the  action  of  perspiration  on  coloring  matters  is  as  yet 
very  imperfect.  Perspiration,  like  every  organic  secretion,  is  very  complex  in  its  com- 
position. According  to  Landois,  it  is  acid  in  reaction  during  repose  and  alkaline  during 
exertion.  Neumeister  claims  that  the  acidity  is  due  to  free  fatty  acid  which  becomes 
neutralized  when  the  secretion  increases  in  quantity.  Trumpy  and  Luchtinger,  how- 
ever, have  more  recently  shown  that  normal  perspiration  is  always  alkaline,  and  that 
the  acid  reaction  proceeds  not  from  the  sweat,  but  from  the  decomposition  of  the  grease 
from  the  skin.  The  cause  of  the  alkalinity  is  not  known  with  certainty.  Trumpy  and 
Luchtinger  consider  it  due  to  carbonate  of  soda,  though  it  may  be  due  to  carbonate  of 
ammonium  formed  from  urea.  Perspiration  contains  neutral  fats,  such  as  palmitin 
and  stearin,  and  also  formic  acid,  butyric  acid,  and  various  higher  fatty  acids.  Among 
its  inorganic  constituents  are  sodium  chloride,  potassium  chloride,  and  small  amounts 
of  the  alkaline  phosphates.  Formerly  the  fastness  of  a  color  to  the  action  of  perspira- 
tion was  tested  by  acetic  acid.  At  the  present  time  treatment  with  lactic  acid  has  been 
substituted.  Actual  exposure  to  perspiration  itself  is,  of  course,  the  best  test.  Next 
to  this  it  is  recommended  to  treat  the  dyed  samples  for  ten  minutes  with  a  solution 
containing  5  grams  of  Castile  soap  and  3  cc.  of  ammonia  water  per  liter.  The  amount 
of  bleeding  which  occurs  will  be  a  fair  test  of  the  fastness  to  perspiration . 


616  TESTING   THE   FASTNESS  OF  COLORS 

]x)ttlc  filled  with  sulphurous  acid  gas  (obtained  by  burning  a  piece  of  sul- 
phur in  the  bottle).  Note  if  the  color  undergoes  any  alteration,  and  cor- 
responding to  the  extent  of  change  classify  the  dj^e  as  not  fast,  fairly  fast, 
or  fast. 

(12)  Fastness  to  Steaming. — In  the  various  finishing  operations,  dyed 
woolen  fabrics  may  be  subjected  to  a  steaming  operation  in  order  to  give 
the  surface  of  the  goods  a  luster  and  a  certain  finish.  This  process  is 
frequently  called  "  decatizing  "  or  "  potting."  *  The  same  operation  is 
carried  out  on  goods  composed  of  wool  and  cotton  yarns  in  order  to  pre- 
vent crinkling,  in  which  case  it  is  called  "  crabbing."  To  test  a  dyestuff 
to  the  influence  of  such  an  operation  proceed  as  follows :  Prepare  a  plaited 
sample  containing  the  dyed  yarn  together  with  white  wool,  and  cotton. 
Steam  the  sample  for  one-half  hour  under  a]:)Out  5  lbs.  pressure.  Note  if 
the  color  suffers  any  alteration,  or  if  it  stains  the  white  yarns.  Accord- 
ing to  the  extent  of  change  or  staining  classify  the  dye  as  not  fast,  fairly 
fast,  or  fast. 

(13)  Fastness  to  Hot  Pressing  or  Ironing. — Woolen  material  employed 
in  the  manufacture  of  suitings,  etc.,  requires  to  be  hot  pressed  or  ironed. 
To  discover  if  a  dyestuff  will  withstand  such  a  treatment,  test  as  follows; 
(a)  Moisten  a  sample  of  the  dyed  yarn  and  press  with  a  hot  iron  till  dry. 
Note  if  the  color  undergoes  any  alteration  on  cooling,  (b)  Moisten  a 
sample  of  the  dyed  yarn  and  cover  with  a  piece  of  white  muslin,  then  press 
with  a  hot  iron  until  dry.  Note  if  the  color  suffers  any  alteration  or  if  it 
stains  the  white  muslin.  If  no  change  takes  place  under  (a)  class  the  dye 
as  fast;  if  it  changes  under  (o)  but  not  under  (h),  or  stains  the  vv^hite  slightly 
without  any  other  perceptible  change,  class  as  fairly  fast;  if  the  color  is 
altered  by  both  (a)  and  (h)  class  as  not  fast. 

3.  Testing  the  Fastness  of  Colors  Dyed  in  Cotton. — In  many  cases 
dyeings  on  cotton  materials  are  tested  in  the  same  manner  as  on  wool; 
but  there  are  deviations  from  the  latter,  owing  to  the  different  character 
of  the  fiber.  The  following  are  the  chief  tests  to  be  applied  to  dyed  cotton 
material : 

(1)  Fastness  to  Light. — Tested  in  the  same  manner  as  with  wool. 

(2)  Fastness  to  Washing. — Tested  in  the  same  manner  as  with  wool. 

(3)  Fastness  to  Fulling. — Tested  in  the  same  manner  as  with  wool. 

(4)  Fastness  to  Rubbing. — Tested  in  the  same  manner  as  with  wool.f 

*  In  the  potting  process  the  use  of  moist  steam  should  be  avoided,  as  there  arc  but 
few  dyes  that  can  withstand  the  simultaneous  action  of  steam  and  water. 

t  The  substantive  colors  on  cotton  are  ordinarily  very  fast  to  rubbing  especially 
when  dyed  with  the  addition  of  soap  or  soluble  oil.  The  use  of  too  much  salt  in  the 
bath,  too  concentrated  a  bath  or  dyeing  at  too  low  a  temperature  may  produce  shades 
that  crock.  Also  colors  that  are  dyed  on  the  padding  machine  are  very  liable  to  rub. 
The  basic  dyes  show  a  rather  inferior  fastness  to  rubbing.     The  same  is  true  with  Para 


TESTING  OF  COLORS  ON   COTTON  617 

(5)  Fastness  to  Water. — Tested  in  the  same  manner  as  with  wool. 

(6)  Fastness  to  Acid.— It  is  frequently  the  practice  to  weave  dyed 
cotton  yarn  with  white  wool  and  subsequently  to  dye  the  wool  with  acid 
colors.  This  is  termed  "  cross-dyeing."  To  discover  if  the  dyed  cotton 
will  withstand  the  action  of  the  boiling  acid  dyebath,  test  as  follows: 
Plait  a  sample  of  the  dyed  yarn  with  white  wool  and  cotton,  and  boil  for 
one  hour  in  a  solution  containing  1  cc.  sulphuric  acid  and  2.5  grams  glauber- 
salt  per  liter.  Then  wash  and  dry.  Note  if  the  color  sustains  any  altera- 
tion or  if  it  bleeds  into  the  white  yarns,*  and  classify  the  dye  as  not  fast, 
fairly  fast,  or  fast. 

(7)  Fastness  to  Weather. — Tested  with  hydrogen  peroxide  in  the  same 
manner  as  with  wool. 

(8)  Fastness  to  Perspiration. — Tested  with  lactic  acid  in  the  same  man- 
ner as  with  wool. 

(9)  Fastness  to  Alkali. — This  is  tested  in  the  following  manner:  (a) 
Steep  a  sample  of  the  dyed  yarn  for  two  minutes  in  cold  ammonia  water 
(full  strength),  and  observe  if  the  color  undergoes  any  alteration,  (b) 
Steep  a  similar  sample  in  a  solution  containing  10  grams  of  soda  ash  to 
100  cc.  of  water  for  two  minutes,  and  dry  without  washing.  Note  if  the 
color  undergoes  any  alteration,  (c)  Plait  a  sample  of  the  dyed  yarn  with 
white  wool  and  cotton,  and  boil  for  one-half  hour  in  a  solution  containing 
2  grams  of  soda  ash  per  liter;  rinse  and  dry.  Observe  if  the  color  suffers 
any  change,  and  if  the  white  yarns  become  tinted.  From  these  tests 
classify  the  color  as  fast,  fairly  fast,  or  not  fast. 

(10)  Fastness  to  Mercerizing. — In  some  cases  cotton  is  mercerized  after 
being  dyed ;  and  as  the  mercerizing  process  consists  in  treating  the  material 
with  strong  solutions  of  caustic  soda,  it  is  necessary  that  the  dyed  color 
should  not  be  affected  by  this  treatment  in  order  to  be  employed  on  this 
class  of  material.  Carry  out  the  test  as  follows:  Steep  a  sample  of  the 
dyed  yarn  in  a  solution  of  caustic  soda  of  50°  Tw.  for  five  minutes;  wash 
well  in  cold  water,  then  in  hot  water,  and  finally  in  water  acidulated  with 
acetic  acid;  dry,  and  observe  if  the  color  has  undergone  any  alteration,  and 
classify  accordingly  as  fast,  fairly  fast,  or  not  fast. 

(11)  Fastness  to  Chlorine  or  Bleaching. — Cotton  fabrics  containing 
white  interwoven  with  colored  yarns  are  frequently  bleached  more  or  less 
thoroughly  in  order  to  clear  the  white;  such  material  as  cotton  toweling 
containing  colored  borders  is  also  bleached  quite  thoroughly.!     To  dis- 

Red,  Turkey  Red  Aniline  Black,  and  Lccwood.  The  sulphur  and  vat  dyes  when  prop- 
erly applied  are  fast  to  crocking. 

*  Many  dyes  are  fast  to  cross-dyeing  with  respect  to  any  alteration  in  the  color  by 
the  action  of  the  acid,  and  yet  will  bleed  into  white  yarns  owing  to  lack  of  fastness  to 
hot  water. 

t  In  modern  laundry  methods  hypochlorite  solutions  are  nearly  always  employed 
for  whitening  cotton  and  linen  goods,  consequently  fastness  to  light  chlorine  bleaching 


618  TESTING   THE   FASTNESS   OF  COLORS 

cover  if  a  dye  will  withstand  the  action  of  bleaching  which  is  done  with 
solutions  of  chloride  of  lime,  the  following  test  should  be  made:  Steep 
a  sample  of  the  dyed  yarn  in  a  cold  solution  of  chloride  of  lime  of  1|°  Tw. 
for  one  hour.  Rinse  in  water  slightly  acidulated  with  hydrochloric  acid, 
then  in  dilute  soap  solution,  and  finally  dry.  Observe  if  the  color  has 
undergone  any  alteration  in  shade,  and  classify  accordingly  as  fast,  fairly 
fast,  and  not  fast. 

(12)  Fastness  to  Lime  or  Street  Dust. — This  is  determined  in  the  same 
manner  as  with  wool. 

(13)  Fastness  to  Steaming.— This  is  determined  in  the  same  manner  as 
with  wool. 

(14)  Fastness  to  Ironing  or  Hot  Pressing. — This  is  determined  in  the 
same  manner  as  with  wool.* 

Dye  ten  test  skeins  of  cotton  with  2  per  cent  of  the  following  dyestuffs, 
and  test  each  color  with  respect  to  fastness  to  the  different  agencies  as 
above  described: 

1.  Benzopurpurin  (substantive  dye). 

2.  Chrysophenine  (substantive  dye). 

3.  Diamine  Blue  RW  (substantive  d3^e  after-treated  with  blucstone). 

4.  Dianil  Direct  Yellow  S  (substantive  dye). 

5.  Dianil  Brown  3G0  (substantive  dye  after-treated  with  chrome). 

6.  Methyl  Violet  (basic  dye  on  tannin-antimony  mordant). 

7.  Magenta  (basic  dye  on  tannin-antimony  mordant). 

8.  Methylene  Blue  (basic  dye  on  tannin-antimony  mordant). 

9.  Cotton  Blue  (acid  dye  on  "  blue  mordant  "). 

10.  Rliodamine  (basic  dye  on  oil-aluminium  mordant). 

4.  Testing  Fastness  of  Colors  Dyed  on  Silk. — Dyeings  on  silk,  as  a  rule, 
do  not  require  as  great  a  degree  of  fastness  as  those  on  wool  and  cotton. 
The  chief  qualities  of  fastness  are  to  light,  rubbing,  and  water.  Certain 
dress  goods  fabrics  of  silk  or  part  silk  also  require  fastness  to  washing ;  the 
same  is  also  true  of  colors  for  silk  shirtings. 

(1)  Fastness  to  Light. — Tested  in  the  same  manner  as  with  wool. 
Also  colors  on  silk  should  not  change  shade  in  artificial  light. 

combined  with  fastness  to  soap  scouring  may  be  described  as  a  test  for  fastness  to  laun- 
dering. Unfortunately  there  are  a  very  few  cotton  dyes  which  are  fast  in  this  respect; 
even  the  sulphur  colors  which  are  quite  fast  to  scouring  are  destroyed  by  hypochlorite 
bleaching.  About  the  only  colors  which  will  successfully  withstand  this  combined 
treatment  are  the  vat  dyes.  On  this  account  they  have  become  of  great  importance  for 
cotton  dyeing,  wherever  the  goods  are  subject  to  kumdry  treatment. 

*  The  substantive  dyes,  as  a  rule,  are  very  sensitive  to  Iteration  in  shade  under  the 
influence  of  dry  heat,  red  dyes  becoming  yellowish,  yellows  bluish,  and  blues  reddish. 
In  other  words,  heating  appears  to  cause  a  displacement  of  the  color  towards  the  violet 
end  of  the  si)ectrum.  There  appears  to  be  some  connection  between  the  chemical  con- 
stitution of  the  dyestuff  and  its  sensitiveness  toward  heat.  Dyes  containing  the  sul- 
phonic  acid  group  are  all  affected  by  ironing  (see  Friedlander,  Chem.  Zeil.,  1900,  p.  1159). 


TESTING   COLORS   OX   SILK 


019 


(2)  Fastness  to  Rubbing. — Tested  in  the  same  manner  as  with  wool. 

(3)  Fastness  to  Water. — Tested  in  the  same  manner  as  with  wool. 

(4)  Fastness  to  Washing. — Tested  in  the  same  manner  as  with  wool. 


TABULATION   OF  TESTS   FOR   FASTNESS   OF  WOOL   DYES. 


Tes'. 

1. 

2. 

3. 

4. 

5. 

6.           7. 

S.      1     9. 

10. 

Light 

Washing: 

Soap  sol 

Wool        

Cotton 

Fulling: 

Wool 

Cotton 

Rubbing 

Water : 

Cold     

Boiling 

Weather: 

H-.0>  dil 

H.O-.  cone 

i 

Acid  and  carbonizing. .  .  . 

Perspiration : 

Wool 

Cotton 

Alkali: 

Wool 

Cotton           



Lime  and  street  dust. .-.  . 

Stoving                  

Steaming: 

Wool 

Cotton 

Color 

White 

Light    

5.  Tabulation  of  Fastness  Required  on  Various  Classes  of  Materials. — 
(a)  Wool. —  (1)  Loose  Wool. — Fastness  to  light,  fulling,  and  potting;  the 
dj'es  recommended  are  mordant  colors  first  (including  the  acid  chrome  and 
meta-chrome  dyeing  colors),  and  substantive  dyes  next.  The  latter  are 
quite  fast  to  scouring  on  wool,  and  fairly  fast  to  fulling;  they  are  especially 
recommended  for  dyeing  in  machines  on  account  of  their  good  solubility. 

(2)  Shoddy,  Mungo  and  Carbonized  Rags. — Fastness  to  fulling  and 
cheapness  in  dyeing;    fastness  to  light  is  seldom  required.     The  dyes 


620 


TESTING   THE   FASTNESS  OF   COLORS 


recommended  are  the  mordant  and  substantive  colors  in  the  first  place, 
and  secondly  the  basic  colors.  The  latter  are  only  fast  to  very  light 
fulling,  but  do  not  stain  white  cotton,  and  are  valuable  on  account  of  their 
great  brilliancy. 


TABULATION   OF  TESTS 

FOR 

FASTNESS 

»  OF 

COTTON  DYES 

Test. 

1. 

2 

3. 

4.         5. 

6. 

7. 

8. 

9. 

10. 

Washing: 

Soap  sol 

Wool 

Cotton 

Fulling: 

Wool 

( 

Cotton 

1 

Rubbing 

Water : 

Cold 

Boiling 

Acids  and  cross-dyeing: 
Color 

Wool 

Cotton 

Weather : 

HjOidil 

H2O2  cone 

Perspiration : 

Wool 

Cotton 

Alkali: 

Ammonia 

Soda,  cold 

Soda,  boiling 

Mercerizing 

Chlorine  or  bleaching .  .  . 

Lime  and  street  dust. .  .  . 

Steaming: 

Wool 

Cotton 

Hot  pressing  or  ironing: 
Color 

White 

(3)  Slubbing  and  Tops. — The  fastness  required  and  the  dyes  recom- 
mended are  the  same  as  for  loose  wool. 

(4)  Weaving  Yarns  (Worsted,  Cheviot  and  Carded  Yarns). — As  these 
are  chiefly  used  for  scouring  and  fulling  purposes,  the  fastness  required 
and  the  dyes  recommended  are  the  same  as  for  loose  wool. 


FASTNESS   REQUIRED   FOR   WOOLEN   GOODS 


621 


(5)  Worsted  Knitting  Yarns  and  Hosiery  Yarns. — These  require  fast- 
ness to  scouring,  perspiration,  and  rubbing.  Substantive  and  mordant 
dyes  are  recommended;  also  the  faster  acid  dyes. 

(6)  Yarns  for  Flannels,  Rugs,  Blankets,  Plaids,  etc. — These  require  a 
moderate  fastness  to  fulling;  also  fastness  to  perspiration  and  rubbing, 
and  for  rug  yarns  fastness  to  stoving  is  frequently  desired.  Substantive 
and  mordant  dyes  are  recommended  as  well  as  the  faster  acid  colors, 
especially  those  which  are  after-treated. 

(7)  Carpet  and  Tapestry  Yarns. — These  require  fastness  to  light, 
cold  water,  and  rubbing;    dyes  possessed  of  good  leveling  properties  are 


Fig.  284. — Two-cylinder  Brushing  Machine  with  Steam  Box,  Flock,  Back  Folder  and 
Scray  Beneath.     (Parks  &  Woolson.) 

also  desired.  The  best  dyes  are  acid  colors  fast  to  light,  then  the  mor- 
dant dyes,  and  the  substantive  dyes  which  are  after-treated  with  blue- 
stone. 

(8)  Worsted  Braids. — These  require  dyes  that  penetrate  well,  and 
that  are  fast  to  light  and  rubbing.  The  same  colors  as  for  the  preceding 
are  recommended. 

(9)  Fancy  Yarns. — Fastness  to  stoving  and  clear  brilliant  colors  are 
usually  desired.  The  best  dyes  to  use  are  the  level  dyeing  acid  colors  and 
the  basic  colors. 

(10)  Piece  Goods  consisting  of  Woolen  Cloths  (Beavers  and  Meltons), 
GentUmen's  Suitings,  Worsted  Coatings,  Cheviots,  Carded  Woolen  Cloths, 
Braids  for  Army  and  Navy  Cloths,  Billiard  Cloth. — In  such  goods  it  is 
desirable  that  the  dyes  be  level  and  penetrate  well;  fastness  to  light,  pot- 


622  TESTING   THE   FASTNESS   OF  COLORS 

ting,  hot  pressing,  and  rubbing  are  also  required,  and  in  some  cases,  fast- 
ness to  carbonizing.  The  dyes  best  to  use  are  the  faster  acid  colors  and 
the  mordant  colors,  and  secondly  the  substantive  dyes. 

(11)  Dress  Goods,  Ladies^  Cloths,  Doeskitis,  Cashmeres,  Crepons,  etc. — 
These  require  the  same  fastness  as  the  preceding,  and  also  fastness  to 
street  dust.     The  same  dyes  are  used  as  with  the  preceding. 

(12)  Flannels. — These  principal^  require  fastness  to  washing  and  liglit ; 
the  dyes  chiefly  used  are  the  acid  and  substantive  colors,  the  latter  being 
largely  employed  for  red  shades. 

(13)  Velvets  and  Plushes. — These  require  fastness  to  light  and  rubbing; 
acid  dyes  are  principally  used. 

(14)  Woolen  Felt. — Good  penetration  and  level  dyeing  is  the  first  con- 
sideration; the  fastness  required  will  vary  with  the  particular  use  to  which 
the  goods  are  put.  The  dyes  mostly  used  are  the  easily  soluble  acid  colors 
and  the  substantive  colors. 

(15)  Hats  of  Wool  ajul  Hair. — In  this  case  fastness  to  light,  potting, 
and  rubbing  is  required;  also  the  color  nmst  penetrate  well.  The  dj'es 
principally  used  are  mordant  colors,  and  readilj''  soluble  acid  colors  fast  to 
light. 

(b)  Cotton. — (1)  Loose  Cotton  and  Slubhing. — These  require  to  be  fast 
to  fulling  and  light,  though  the  requirements  vary  greatly,  according  to 
the  use  to  which  the  material  is  to  be  put.  The  dyes  mosth'  used  are  the 
substantive  colors,  dyed  direct,  diazotized  and  developed,  or  after-treated; 
also  substantive  dyes  topped  with  basic  colors,  and  even  basic  colors  alone. 

(2)  Fancy  Weaving  Yarns,  Cotton  Warps  for  Union  Goods,  Knitting 
Yarns,  Hosiery  Yar7is. — These  require  fastness  to  scouring  (and  some- 
times fulling)  to  cross-dyeing,  to  light,  and  generally  to  perspiration, 
though  the  degree  of  fastness  will  necessarily  vary  considerably  with  the 
use  to  which  the  j-arn  is  to  be  put.  The  dyes  recommended  are  the  diazo- 
tized and  developed  and  the  after-treated  substantive  colors,  sulphur  colors, 
basic  colors,  and  substantive  colors  topped  with  basic;  for  light  shades, 
the  direct  dj'ed  substantive  colors.  For  cop  dj'eing  the  substantive  colors 
of  ready  solubility  are  principallj^  used. 

(3)  Yams  for  Draperies,  Upholstery,  etc. — These   chiefl}'  require  fast-  . 
ness  to  light  and  rubbing.     The  dyes  mostly  used  are  the  substantive 
colors,  the  basic  colors,  and  some  of  the  acid  colors. 

(4)  Sewing  Cotton. — This  requires  fastness  to  light  and  rubbing.  The 
substantive  and  basic  dyes  are  chieflj^  used. 

(5)  Cotton  Hosiery  and  Knit-goods. — These  require  fastness  to  wash- 
ing, perspiration,  rubbing,  and  somethnes  light.  The  dyes  must  also 
penetrate  well.  The  colors  used  are  the  same  as  for  knitting  yarns;  also 
Aniline  Black  and  the  sulphur  colors. 

(6)  Piece  Goods  consisting  of  Moleskins,  Cotton  Worsteds,  Beavers,  Fus- 


FASTNESS   REQUIRED   FOR   COTTON   GOODS  G23 

tians,  Flannelettes,  Sateens,  Plushes,  Velvets,  Corduroys,  etc. — These  usually 
require  fastness  to  perspiration,  light,  rubbing,  hot  pressing,  and  in  some 
cases  also  fastness  to  washing.  The  dyes  mostly  used  are  the  substantive 
colors  dyed  direct,  also  diazotized  and  developed,  and  after-treated;  also 
the  sulphur  dyes;  also  substantive  dyes  topped  with  basic  colors,  and  at 
times  basic  dyes  alone. 

(7)  Cotton  Linings,  Bobbinnet,  Tulle,  etc. — These  require  fastness  to 
rubbing,  perspiration,  and  frequently  hot  pressing.  The  dyes  chiefly 
used  are  the  substantive  colors  dyed  direct,  diazotized  and  developed,  or 
topped  with  basic  dyes;  the  sulphur  dyes;  and  the  basic  dyes.  Bob- 
binnet is  frequently  dyed  in  the  sizing. 

(8)  Bookbinders'  Cloth. — About  the  only  fastness  required  is  to  Kght. 
The  dyeing  is  frequently  done  in  the  sizing,  using  acid  dyes,  basic  dyes,  and 
substantive  dyes. 

(c)  Union  Goods.— (1)  Thread  Waste,  Shoddy,  eic— Moderate  fast- 
ness to  fulling  is  usually  required  together  with  cheapness  of  dyeing.  The 
dyes  mostly  used  are  the  substantive  colors,  either  alone  or  in  conjunc- 
tion with  neutral  dyeing  acid  colors;  also  after-treated  substantive  colors. 

(2)  Merino  and  Angola  Yarns,  Braids,  etc. — The  requirements  fcr 
fastness  vary  with  the  application.  The  dyes  used  are  those  given  above, 
also  substantive  dyes  topped  with  basic  colors. 

(3)  Hosiery  Yarns. — These  require  fastness  to  perspiration,  washing, 
and  rubbing.     The  dyes  employed  are  those  given  above. 

(4)  Piece  Goods  co7isisting  of  Cotton  Warp  Suitings,  Woolens,  Dress 
Goods,  Shawls,  Crewels,  Astrachans,  Italian  Cloth,  Serges,  Hosiery,  Felt, 
and  Flannels. — The  requirements  for  fastness  vary  with  the  nature  and 
use  of  the  material;  in  general,  fastness  to  washing  and  rubbing  is  desired: 
fastness  to  light  is  of  minor  importance  with  Hnings  and  hosiery.  Tie 
dyes  mostly  used  are  the  substantive  dyes  either  alone  or  in  combinaticn 
with  the  neutral  dyeing  acid  colors. 

(5)  Ladies'  Cloths,  Presidents,  Whitneys,  Moscows,  Beavers,  Worsted 
Coatings,  etc. — The  only  important  requirement  is  sufficient  fastness  to 
light,  water,  rubbing,  and  hot  pressing.  -The  dye  should  cover  the  cotton 
well,  be  level  dyeing,  and  have  good  penetration.  The  substantive  dyes 
are  principally  used,  either  alone  or  in  combination  with  neutral  dyeing 
acid  colors. 


CHAPTER   XXVII 
APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

1.  The  Dyeing  of  Leather. — Leather  is  a  fibrous  material  composed  of 
animal  tissue  possessing  chemical  characteristics  verj-  similar  to  those  of 
wool,  consequently  it  would  be  natural  to  expect  that  this  material  would 
react  towards  dyestuffs  in  a  manner  somewhat  analogous  to  that  of  wool. 
Leather  is  also  a  porous  tissue  capable  of  absorbmg  bj^  mere  capillary 
action  various  materials  from  solution  and  thus  becoming  dyed  or  mor- 
danted. Furthermore,  leather  must  also  be  considered  as  a  colloid  with 
respect  to  its  constituent  fibers  and  therefore  ha\ing  colloid  reactions  hke 
other  fibers,  such  as  formmg  solid  solutions  with  dyes  and  other  smiilar 
bodies. 

The  properties  of  leather  with  respect  to  dyeing  depend  to  a  large  extent 
on  the  method  emploj'ed  in  its  tanning  and  also  somewhat  upon  the 
character  of  the  skin  from  which  the  leather  has  been  made.  There  are 
four  general  methods  of  tanning  used  in  the  preparation  of  leather:  (a) 
Vegetable  tanning,  bj"  the  use  of  tannic  acid  or  vegetable  extracts  rich  in 
tannic  acid,  such  as  sumac,  hemlock,  oak-bark,  quebracho,  etc.  (b)  Chrome 
tanning,  where  the  leather  is  formed  by  the  action  of  chromium  compounds 
on  the  skins,  (c)  Alum  tanning,  obtained  by  the  action  of  alum  solutions 
giving  a  hght-colored  leather,  (d)  Oil  tannage,  by  the  action  of  certain 
oils  giving  a  leather  product  such  as  chamois.  Vegetable  tanning  is  used 
principally  for  the  preparation  of  hea\y  leathers,  and  it  must  be  borne 
in  mind  that  the  tannin  compounds  influence  the  reaction  of  the  leather 
with  dyestuffs.  Chrome  tannage  is  now  extensiveh^  employed  for  lighter 
weights  of  leather  such  as  kid  and  sheepskins;  the  dyeing  properties  are 
influenced  by  the  presence  of  chromium  compounds,  which  also  give  the 
leather  a  green  color  and  serve  the  purpose  of  a  chromium  mordant. 
Alum  tanning  is  used  for  Ught-weight  leathers,  chiefly  to  be  of  a  wliite 
color  or  to  be  dj'ed  in  hght  shades,  such  as  leather  for  glove  material 
and  such  like.  Tliis  leather  contains  alum  compounds  and  tliis  influences 
its  reaction  ^\•ith  dyes,  as  it  may  be  considered  as  mordanted  with  alum. 
Chamois,  or  oil-tanned  leather,  is  a  very  porous,  soft  leather  of  a  hght 
creamy  color.  Though  it  may  have  formerl}'  been  made  from  the  skins 
of  the  ciiamois  it  is  now  made  from  the  skins  of  goats  and  sheep. 

624 


LEATHER   D\T:ING 


625 


In  the  dyeing  of  leather  the  basic,  acid,  and  substantive  dyes  are  the 
principal  ones  employed,  the  other  classes  of  dyes  not  coming  into  con- 
sideration at  all  for  this  purpose.  The  preparation  of  leather  for  dyeing 
consists  principally  of  freeing  it  as  far  as  possible  from  foreign  substances 
adhering  to  it  from  the  tanning  process,  and  tliis  is  usually  accomplished 
by  allowing  the  skins  to  lie  for  some  time  in  running  water  in  order  to  wash 
off  the  impurities.  This  operation  is  generally  carried  out  in  a  drum, 
which  consists  of  a  closed  rotating  wooden  vat  or  tank  in  which  the  leather 
is  placed,  together  with  sufficient  water,  and  the  drum  is  then  run  for 


Fig.  285. — Drum  Machine  for  Dyeing  Leather. 


three  to  four  hours,  then  fresh  lukewarm  water  is  added  and  the  leather  is 
drummed  for  ten  minutes  longer;  it  should  then  possess  a  characteristic 
slipperly  handle. 

Leather  prepared  with  vegetable  tanning  must  be  freed  from  all  excess 
of  tannin  material,  as  if  tliis  is  not  done  dye  spots  are  liable  to  be  formed, 
especially  when  dyeing  with  the  basic  colors.  For  the  preparation  of 
vegetable-tanned  sheepskins  the  following  method  is  recommended: 
Scour  in  the  drum  with  a  weak  solution  of  soda  ash  (containing  about  1  lb. 
of  soda  ash  to  25  gallons  of  water)  for  the  purpose  of  removing  any  unfixed 
tannin  and  greasy  matters;  then  rinse  again  in  the  drum  for  one-half  hour 
tvith  lukewarm  water,  and  afterwards  run  for  five  minutes  in  a  bath  con- 


626 


APPLICATION  OF  DYES  TO   VARIOTS  MATERIALS 


taining  1  part  of  sulphuric  acid  to  GO  parts  of  water  at  a  temperature  of 
60°  T.  for  the  purpose  of  removing  dirt  and  grease.  Finally  rinse  in  cold 
water  to  vash  out  the  sulphuric  acid.  When  very  dark  colors  are  to  be 
dyed  it  may  not  be  necessary  to  give  the  treatment  with  sulphuric  acid. 
The  leather  thus  \)repared  is  now  ready  for  dyeing,  which  is  carried  out 
in  the  drum  with  a  dyebath  starting  at  a  temperature  of  100  to  120°  F. 
and  running  until  the  hquor  is  cold. 

In  the  dyeing  of  sumac-tanned  leather  with  the  basic  colors  the  follow- 
ing method  is  recommended :  After  thorough  cleaning  dye  with  a  solution 
containing  the  well-dissolved  dyestuff  with  the  addition  of  1  to  2  pints  of 
acetic  acid  per  100  gallons  of  water  (for  the  correction  of  the  hardness) 


Fig.  286. — Putting-out  Machine  Used  in  Leather  Dyeing. 


There  are  two  methods  adopted  in  the  application  of  the  dyebath:  (a) 
Brushing,  where  the  color  solution  is  applied  to  the  surface  of  the  leather 
by  means  of  a  brush,  the  temperature  of  the  dye  liquor  being  maintained 
at  75  to  120°  F.  (b)  Dipping,  where  two  skins  are  paired  together  with 
the  flesh-side  in  and  then  drawn  through  the  dyebath  in  a  tray  at  a  tem- 
perature of  120  to  140°  F.  In  the  dipping  method  it  is  customary  to 
employ  two  baths,  the  color  solution  being  prepared  by  dissolving  4  ozs. 
of  dyestuff  in  |  gallon  of  water.  For  the  fifst  bath  use  |  pint  of  this  dye 
solution  diluted  with  three  to  four  times  its  amount  of  water.  The  diluted 
color  solution  is  used  for  dyeing  the  first  pair  of  skins  and  these  are  subse- 
quently dyed  to  the  proper  full  color  in  a  small  amount  of  the  undiluted 
dyestuff  solution,  rinsed  in  cold  water  and  then  dried  in  the  open  air.  The 
strong  color  solution  for  the  last  bath  is  used  for  the  preliminary  dyeing  of 


DYEING   VEGETABLE-TANNED   LEATHER 


627 


the  next  pair  of  skins,  whicli  are  then  subsequently  brought  to  the  proper 
shade  in  the  strong  color  solution,  and  so  on.  The  purpose  of  dyeing  first 
in  the  weak  dye  liquor  is  to  prevent  uneven  colors,  as  the  dyestuff  is  very 
rapidly  and  greedily  taken  up  by  the  leather,  and  consequently  if  the  color 
solution  is  not  sufficiently  diluted  spots  and  streaks  will  result.  After 
dyeing  the  skins  should  be  rinsed  in  lukewarm  water,  stretched,  and 
softened  with  linseed  oil,  dried,  rubbed  with  diluted  milk,  then  albumin 
and  finally  dried  again.  These  after-treatments  are  necessary  to  prevent 
the  dyed  skins  from  becoming  hard  and  tough  on  drying  out.  Many  of 
the  basic  colors  when  applied  in  very  heavy  shades  produce  a  metallic 
luster  on  the  leather,  and  this  is  usually  removed  by  running  the  skins 
through  a  bath  of  dilute  acetic  acid.  When  it  is  necessary  to  darken 
or  sadden  the  color  a  treatment  with  acetate  of  iron  or  chrome  may  be 
given.  When  the  skins  have  a  hard  grain  so  that  the  colors  are  not  fixed 
well,  better  results  may  be  obtained  by  mordanting  previously  with  tartar 
emetic  (or  other  suitable  antimony  salt) .  The  use  of  a  solution  of  borax  is 
also  serviceable  in  softening  the  grain  (particularly  in  the  case  of  kid  and 
goat  skins)  when  the  leather  still  contains  residues  of  greasy  matters. 
When  necessary  grease  may  also  be  removed  by  a  treatment  with  carbon 
tetrachloride  or  benzene. 

Vegetable-tanned  leather  may  be  dyed  with  the  acid  colors  by  using 
the  dye  liquor  at  130°  F.  containing  the  well-dissolved  color  with  the 
addition  of  |  pint  of  sulphuric  acid  to  100  gallons  of  water.  When  using 
a  mixture  of  acid  dyes  to  produce  a  compound  shade  it  is  best  not  to  mix 
the  dyes  in  one  bath,  but  to  use  them  one  after  the  other,  as  by  this  means 
much  clearer  tones  of  color  will  be  the  result. 


Dyestuffs  Suitable  for  the  Dyeing  of  Vegetable  Tanned  Leather. 


Auracine  G 
Auramine 

Azo  Phosphine  GO,  BRO 
Bismarck  Brown  F,  M,  R 
Brilliant  Green 
Brilliant  Phosphine  G 
Brilliant  Rhoduline  Red  B 
Brown  for  Leather  O 
Canelle 
Cardinal  G,  R 
Cerise  GO,  R 
China  Green 
Chrysoidine  G,  R 
Coriphosphine  O 
Diamond  Fuchsine 
Grenadine  O,  R 


(A)  Basic  Colors 

Induline  L  (water  sol.) 
Janus  Black  I 
Janus  Blue  B 
Janus  Brown  R 
Janus  Green  G 
Janus  Red  B 
Janus  Yellow  G,  R 
Leather  Black  V,  T,  G 
Leather  Brown  2G 
Leather  Green  O 
Leather  Yellow  GO.  2G 
Malachite  Green 
Maroon  O 
Methyl  Green  I 
Methyl  Violets 
Methylene  Blue  2B 


Methylene  Gray  O,  NF 
Methylene  Green 
New  Blue  R 
New  Fast  Blue 
New  Magenta 
Paper  Scarlet  G,  B 
Patent  Phosphine  G,  M 
Phosphine  O,  P 
Red  for  Leather  O,  R,  G 
Rhodamine  B 
Rhoduline  Violet 
Russia  Red  D 
Saffron  Red  O 
Safranine  FF 
Turquo  se  Blue  2B,  G 
Vesuvine 


628 


APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 


(B)  Acid  Colors 


Acid  Anthracene  Brown  R 

Acid  Brown  B 

Acid  Cerise  O 

Acid  Green  2B,  2G 

Acid  Magenta 

Acid  Maroon  O 

Acid  Phosphine  JO 

Acid  Violet  4B 

Azo  Yellow 

Bordeaux  extra,  G 

Brilliant  Croceine  3B 

Brilliant  Orange  G,  O,  R 

China  Blue 

Citronine 


Claret  Red  G,  R,  B 

Cotton  Blue 

Croceine  Orange  G,  R 

Croceine  Scarlet  2BN,  SB 

Eosi  I 

Fast  Blue  O,  R,  5B 

Fast  Brown 

Fast  Green 

Fast  Red  A 

Imperial  Scarlet  3B 

Indian  Yellow  G,  R 

Induline 

Lyons  Blue 

Naphthol  Yellow  S 


New  Acid  Green 
New  Patent  Blue 
Nigrosine  (water  sol.) 
Orange  II,  R 
Orseilline  R,  B 
Patent  Blue  V,  A 
Phenylemine  Black  4B 
Phloxine  G,  oB 
Pure  Blue  O 
Quinoline  Yellow 
Resorcine  Brown 
Rosazeine  4G,  O 
Victoria  Yellow 
Wool  Blue  N 


For  the  dyeing  of  chrome-tanned  leather,  basic,  acid,  and  certain  of 
the  substantive  dyes  may  be  emploA'ed.  In  the  dyeing  of  basic  colors  the 
chrome-tanned  leather  should  first  be  treated  with  a  suspension  of  chalk 
or  a  solution  of  borax  or  ammonia  m  order  to  neutralize  and  remove  all  the 
acid  in  the  leather.  The  skins  are  then  drummed  in  a  tannin  bath  (sumac 
or  gambier)  for  one-half  hour,  and  then  well  washed  and  dyed  in  the  drum 
with  the  solution  of  the  basic  color  at  a  temperature  of  about  120°  F. 
The  dipping  method  of  dyeing  may  also  be  employed. 

Acid  colors  are  usually  employed  on  chi'ome-tanned  leather  where 
a  good  penetration  of  the  dyestuff  is  desired.  The  dyebath  is  prepared 
sunply  vdXh  the  solution  of  the  acid  dyestuff  and  applied  either  in  the  drum 
or  by  dipping  at  110  to  120°  F.  for  one-half  hour,  finally  adding  a  small 
amount  of  acetic  acid  to  the  bath  to  obtain  better  exhaustion. 


Dyestuffs  Suitable  for  the  Dyeing  of  Chrome-Tanned  Leather. 


Auracine  G 

Auramine 

Azo  Phosphine  GO,  BRO 

Brilliant  Green 

Brown  for  Leather 

Cardinal  G 

Cerise  G,  R 

Chrome  Leather  Yellow 

Chrj'soidine  G,  R 

Coriphosphine  O 


(A)  Basic  Colors 

Fast  Blue  for  Cotton 
Grenadine  O 
Janus  Colors 
Leather  Black  T 
Magenta 
Malachite  Green 
Methyl  ^'iolet  2B 
Methylene  Blue 
Methylene  Green 


New  Fast  Blue  3R 
New  Magenta 
Phosphine  O,  P 
Red  for  Leather 
Russia  Red  D 
Saffron  Red  O 
Safranine  FF 
Vesuvine  4BG 
Yellow  for  Leather 


DYEING  CHROME-TANNED   LEATHER 


629 


Acid  Cerise  O 
Acid  Green 
Acid  Magenta 
Acid  Maroon  O 
Azo  Yellow 
Bordeaux  extra,  G 
Brilliant  Croceine  3B 
Brilliant  Orange  G,  O,  R 
China  Blue 


(B)  Acid  CoJors 

Claret  Red  G,  R,  B 

Croceine  Orange  G 

Eosin 

Fast  Blue  O,  R 

Fast  Brown 

Fast  Red  A 

Indian  Yellow  G,  R 

Induline  B 

Lyons  Blue 


Nigrosine  (water  sol.) 
Orange  II 
Orseilline  R,  B 
Patent  Blue  V,  A 
Phloxine 
Rosazeine 
Scarlet  G,  R 
Victoria  Yellow 


Acetylene  Blue  3B 
Benzo  Fast  Blue  BN 
Chlorantine  Red  4B 
Chlorantine  Yellow  2J 
Chrome  Leather  Brown 


(C)  Substantive  Dyes 

Cupranil  Brown  G 
DianU  Blue  G,  B 
Dianil  Brown  R 
Dianil  Orange  G 
DianH  Yellow  3G,  R 


Direct  Deep  Black  RW 
Direct  Olive 
Leather  Black  C,  E 
Pluto  Black  BS 


The  substantive  colors  are  applied  to  chromed  leather  by  running  at  a 
temperature  of  150  to  160°  F.  for  one-half  hour.  When  suitable  dyes 
are  employed  the  bath  is  almost  completely  exhausted. 


Fig.  287. — Cotton  Shearing  and  Brushing  Machine.     (Curtis  &  Marble.) 

After  chrome-tanned  skins  have  been  dyed  they  should  be  treated 
in  the  drum  for  one-half  hour  with  an  emulsion  of  olive-oil  soap  and 
neatsfoot  oil  or  egg-yolk,  then  stretched  and  oiled  with  neatsfoot  oil  or 
linseed  oil  and  allowed  to  dry.  Afterwards  lay  the  leather  in  damp  saw- 
dust, stake  it  and  wet  out  with  a  strong  solution  of  albumin. 

Alum-tanned  leather  is  first  rinsed  well,  in  order  thoroughly  to  remove 
any  excess  of  alum,  and  is  then  dyed  at  a  temperature  of  115°  F.  either  by 
the  dipping  or  the  brushing  method,  using  the  basic  colors  in  a  neutral 
bath  or  the  acid  colors  in  a  weak  sulphuric  acid  bath  or  the  phthaleine 
colors  (Eosin,  etc.)  in  a  weak  bath  of  acetic  acid.  The  dyes  employed 
and  the  baths  are  prepared  in  practically  the  same  manner  as  with  chrome- 
tanned  leather. 


630  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

Besides  the  coal-tar  dyes,  some  of  the  natural  vegetable  dj^es  are  still 
used  to  a  considerable  extent  for  the  dyeing  of  leather.  Logwood  is  used 
for  blacks  and  for  toning  other  colors  such  as  browns  and  tans;  Quercitron 
and  Flavine  also  find  extensive  use  as  yellow  dyes,  both  as  self-shades  and 
as  components  in  the  production  of  browns  and  tans.  Quebracho,  which 
is  so  largely  used  as  a  tannin  agent  for  leather,  also  dyes  the  leather  a 
reddish  brown  color.  The  same  is  true  of  nearly  all  the  other  tannins 
used  for  leather,  they  not  only  cause  a  tanning  of  the  skin,  but  also  dye  it 
various  shades  of  brown  depending  on  the  origin  and  nature  of  the  tannin. 

2.  The  Dyeing  of  Paper. — Paper  may  be  considered  as  a  web  or  fabric 
of  interlaced  vegetable  fibers  made  by  enmeshing  them  on  a  screen  from 
a  broth  or  suspension  of  these  fibers  in  water.  Its  properties  with  respect 
to  dj^estufTs  are  about  the  same  as  cotton  and  the  other  vegetable  fibers. 
Paper  may  be  dyed  either  in  the  form  of  pulp  (wliich  consists  of  a  sus- 
pension of  the  fibers  in  water)  previous  to  being  converted  into  paper 
or  in  the  form  of  the  prepared  paper.  In  the  former  case  the  pulp  is  con- 
tained in  a  mixing  tank  or  beater  and  the  dyestuff  solutions  and  other  neces- 
sary' ingredients  are  added  directly  to  the  pulp  and  thoroughly  incorporated 
with  it  b}'  mixing.  The  dj^e  is  either  taken  up  directlj^  by  the  fiber  or  is 
precipitated  in  and  on  the  fiber  by  suitable  mordants.  In  the  case  of 
dyeing  the  prepared  paper  itself  the  latter  in  open  width  is  run  through  a 
solution  of  the  dyestuff,  which  it  takes  up  either  by  combination  with  the 
fiber  or  by  simple  absorption  and  becomes  dyed  thereby.  In  some  cases 
where  the  paper  is  heavily  coated  and  dj^ed  on  one  side  only  the  coloring 
matter  in  the  form  of  a  proper  paste  or  solution  is  brushed  on  the  surface 
of  the  paper  or  applied  bj^  means  of  rollers,  in  which  case  it  is  more  of  a 
painting  operation  than  a  real  dyeing  one. 

Paper  may  consist  of  various  kinds  of  fibers  possessing  somewhat  differ- 
ant  characteristics  as  far  as  their  dyeing  properties  are  concerned.  These 
different  fibers  may  be  roughly  classified  as  follows:  (a)  mechanical  wood 
pulp,  consisting  of  woody  tissue  reduced  to  the  fiber  form  b3^  mechanical 
disintegration;  (6)  chemical  wood  pulp,  consisting  of  fibers  prepared  from 
woody  tissue  by  treatment  with  proper  chemical  agents,  such  as  sodium 
(or  calcium)  bisulphite,  giving  sulphite  pulp,  or  caustic  soda  giving  soda 
pulp,  or  sodium  sulphide  giving  sulphate  pulp;  (c)  rag  pulp  made  from  rags 
and  miscellaneous  waste  of  cotton  and  linen  fabrics;  (d)  pulp  made  from 
various  grasses  or  straws  such  as  esparto.  In  this  country  paper  is  prin- 
cipally made  from  mechanical  wood  pulp,  sulphite  pulp,  and  rag  pulp, 
cither  employed  singly  or  in  mixtures  in  various  proportions  depending 
upon  the  quality  of  the  paper  desired.  ^Mechanical  wood  pulp  gives  the 
lowest  grade  of  paper  and  is  principally  used  for  newspaper  stock,  cheap 
printing  papers,  paper  for  linings,  wall  paper,  etc.  It  contains  a  consid- 
erable amount  of  lignin  matter  and  other  matters  differing  from  pure  eel- 


PAPER  DYEING  631 

lulose.  Sulphite  pulp  is  of  a  much  higher  grade  and  is  used  for  making 
the  better  class  of  printing  and  book  papers  and  writing  papers.  It  con- 
sists of  rather  pure  cellulose  and  may  be  bleached  to  a  fine  white  stock.  It 
is  largely  mixed  with  mechanical  wood  pulp  to  produce  varying  grades  of 
paper  stock.  Rag  pulp  is  used  chiefly  in  admixture  with  more  or  less 
sulphite  pulp  for  the  production  of  high-grade  writing  papers  and  other 
grades  of  paper  requiring  cotton  or  hnen  fibers  in  order  to  obtain  a  special 
quahty.  Sulphate  pulp  gives  a  tough  fiber  which  is  rather  highly  hydro- 
lyzed  cellulose^  and  it  is  used  principally  for  the  production  of  tough  wrap- 
ping papers  and  similar  stock.  Jute  waste  and  butts  are  also  employed 
extensively  as  a  basis  for  paper  pulp  as  are  also  various  other  vegetable 
fiber  wastes. 

The  dyes  that  are  principally  used  for  the  coloring  of  paper  are  the 
basic,  acid,  substantive,  and  to  a  lesser  extent  some  of  the  sulphur  colors 
as  well  as  some  of  the  vat  dyes  where  the  production  of  colors  or  tints  of 
great  fastness  to  light  is  desired. 

Paper  pulp  is  dyed  in  the  beater  with  the  basic  dyes  in  the  following 
manner:  There  is  first  added  to  the  pulp  in  the  beater  2  to  4  per  cent  of 
aluminium  sulphate  dissolved  in  water  and  the  beater  is  allowed  to  run 
for  ten  minutes;  then  add  the  solution  of  the  basic  dye  and  allow  the 
beater  to  run  for  another  ten  minutes ;  next  add  a  solution  of  4  per  cent  ol 
resin  soap  (prepared  by  saponifying  1  lb.  of  resin  with  4  ozs.  of  soda  ash  ir, 
1  gallon  of  water),  and  run  for  fifteen  minutes,  when  the  back  waste  water 
should  show  clear,  indicating  that  all  the  dye  has  been  taken  up  by  the  pulp. 
In  this  method  of  dyeing  the  dyestufT  is  thrown  down  by  the  precipitate  of 
aluminium  resin  soap  incorporated  with  the  fiber  pulp.  When  dyeing 
colors  involving  the  use  of  a  mixture  of  several  dyes  it  is  best  not  to  add 
the  mixed  dye  solution,  but  to  add  the  several  colors  in  solution  separately. 
The  dyestuff  solutions  as  well  as  the  other  solutions  employed  should  be 
rather  dilute  in  order  to  enhance  the  uniformity  of  their  distribution  as 
far  as  possible. 

The  acid  dyes  are  applied  in  the  same  manner  as  above  described 
for  the  basic  colors.  When  mixtures  of  mechanical  and  sulpliite  pulp 
are  used  (as  is  most  frequently  the  case)  the  two  fibers  often  do  not  come 
up  the  same  color  with  the  acid  dyes;  therefore  it  is  recommended  that 
paper  pulp  dyed  with  the  acid  colors  should  be  topped  with  basic  dyes  as 
these  come  up  evenly  on  boih  fibers.  The  solution  of  the  basic  dye  should 
be  added  after  that  of  the  acid  color  has  been  properly  and  thoroughly 
worked  in. 

The  substantive  and  sulphur  colors  are  also  applied  in  the  same  man- 
ner as  the  basic  dyes  with  the  use  of  aluminium  sulphate  and  resin  soap. 
Some  of  the  substantive  dyes  may  be  applied  without  any  additions  of 
these  chemicals,  but  the  color  is  apt  to  bleed  out  into  water  and  cause 


632  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

stains.  The  sulphur  dyes  must  be  first  dissolved  in  the  necessary  quan- 
tity of  sodium  sulphide. 

The  dyeing  of  made-up  paper  (so-called  staining)  is  done  almost  entirely 
with  the  acid  and  basic  dyes.  The  colors  should  be  well  dissolved  m  water 
and  the  solutions  filtered.  The  color  solution  is  brushed  on  the  paper  either 
by  hand  or  by  the  use  of  suitable  brush  machines.  Tissue  paper  is  also 
extensively  dyed  for  use  in  making  paper  flowers  and  other  ornamental 
objects;  in  this  case  acid,  basic  and  substantive  dj^es  may  be  employed 
and  the  dyeing  is  usually  done  in  a  dyeing  machine  in  which  the  paper  is 
run  through  the  concentrated  dye  solution  and  then  on  to  hot  cylinders 
for  drjnng.  Wall  paper  and  coated  paper  are  usually  dyed  by  an  opera- 
tion similar  to  that  of  padding,  the  strong  color  solution  together  with 
suitable  sizing  and  filling  agents  being  applied  to  one  surface  of  the  paper 
in  a  padding  machine  bj'-  means  of  rollers  and  then  dried.  In  the  d3'eing 
by  this  method  pigment  colors  may  also  be  used,  as  well  as  the  coal-tar 
color-lakes  made  by  precipitating  the  dyestuff  on  a  metalhc  base. 

3.  The  Dyeing  of  Furs, — The  dj-eing  of  furs  is  a  rather  special  art,  fci' 
in  this  case  the  dyer  is  not  only  interested  in  the  production  of  a  certain 
color  on  the  material,  but  must  also  be  concerned  ^\ith  certain  other  equal- 
ities of  the  fur  in  order  that  it  may  hcve  value  and  beauty.  The  luster, 
the  lay  of  the  fiber,  the  gradation  of  the  color  from  the  outer  to  the  inner 
portion  of  the  fur,  the  color  and  appearance  of  the  tips  of  tha  fibers,  the 
character  and  quaUty  of  the  skin  holding  the  fur  as  well  as  its  color,  have 
all  to  be  considered  in  the  process  of  fur  dj-eing,  and  this  requires  intel- 
ligent and  carefully  trained  art  as  well  as  dj'eing  technique.  Furthermore, 
the  dyeing  of  furs  is  rather  lunited  in  range  of  colors;  browns  of  various 
shades  are  mostly  used,  blacks  to  some  extent,  and  to.  a  far  less  degree  the 
fancy  colors.  The  production  of  dark  browns  and  blacks  are  the  chief 
consideration  in  fur  th^eing,  and  these  colors  are  produced  principally  with 
a  few  special  materials  or  preparations  consisting  of  meta-phenjdene-dia- 
mine,  para-phenylene-diamine  and  amino-phenol,  either  alone  or  in  mix- 
tures. The  dyeing  resembles  that  of  the  application  of  Anihne  Black,  in 
that  these  preparations  are  oxidized  on  the  fiber  in  the  same  manner  as 
aniline,  thus  building  up  the  dj'e  directly  in  the  fiber. 

In  the  dyeing  of  furs  the  materials  are  first  well  scoured  in  lukewarm 
water  containing  olive  oil  soap  and  ammonia,  and  then  rinsed  well.* 

*  This  is  for  the  purpose  of  removing  the  oil  and  grease  from  the  fur  and  is  technically 
known  as  "  killing  "  the  fur.  The  chief  methods  of  scouring  are  as  follows:  (o)  steep 
for  two  hours  in  a  cold  2  per  cent  solution  of  soda  ash;  (6)  wash  in  a  solution  containing 
1  gram  of  soap  and  1  cc.  of  ammonia  per  liter  of  water  for  one  to  two  hours  at  120°  F.; 
(c)  wash  in  milk-of-lime  prepared  with  2  liters  of  water,  60  grams  of  powdered  ammo- 
nium chloride,  15  grams  of  aluminium  sulphate  dissolved  in  water,  and  then  adding 
with  constant  stirring  200  grams  of  quicklime  made  into  a  milk  with  4  liters  of  water. 


FUR  DYEING  633 

The  fur  is  then  steeped  for  six  hours  in  a  sokition  of  chrome  containing 
5  grams  of  sodium  bichromate  per  hter.  Rinse  well  and  place  in  a  solution 
containing  3  grams  of  meta-phenylene-diamine  and  2  grams  of  para- 
phenylene-diamine  per  liter  of  water  with  the  addition  of  a  small  amount 
of  hydrochloric  acid  or  vanadium  chloride  (to  act  as  a  carrier  of  oxygen). 
After  thoroughly  working  the  solution  into  the  fur  allow  it  to  steep  in  the 
liquor  for  about  six  hours.  Then  remove  the  fur,  rinse  well,  and  dry. 
This  process  should  give  a  satisfactory  black  on  the  fur"  for  the  pro- 
duction of  brown  shades  lesser  quantities  of  the  above  ingredients  should 
be  used,  either  alone  or  together.  Amino-phenol  may  also  be  used  for  the 
same  purpose.  The  proper  shade  can  be  obtained  only  by  careful  experi- 
ment with  a  sample  of  the  fur  to  be  used.  After  the  fur  has  been  dyed  it  is 
of  advantage  to  rub  in  neatsfoot  oil  on  the  flesh  side  of  the  skins  in  order 
to  keep  the  leather  part  soft  and  pliable.  Meta-phenylene-diamine  and 
para-phenylene-diamine  and  amino-phenol  are  to  be  met  with  in  trade 
under  a  variety  of  names  such  as  Furrol,  Furrine,  etc.  These  dyes  are 
frequently  specially  prepared  mixtures  adapted  to  the  production  of  various 
tones  of  color. 

Various  basic  dyes  may  also  be  employed  in  the  dyeing  of  fur,  being 
applied  in  a  lukewarm  neutral  bath,  the  fur  being  steeped  in  dye  liquor  for 
one  to  two  hours.  Most  of  the  basic  dyes  may  be  used  for  this  purpose, 
and  they  may  be  applied  for  the  purpose  of  shading  the  brown  or  black 
colors  obtained  with  the  phenylene-diamine  and  amino-phenol  dyes.  In 
applying  the  Furrol  dyes  the  colors  are  usually  developed  by  an  after- 
treatment  with  hydrogen  peroxide,  or  the  peroxide  may  be  added  to  the 
dyebath,  which  is  then  prepared  as  follows:  For  10  gallons  of  dye  liquor 
use  1|  to  6  ozs.  of  Furrol  dyestuff  dissolved  in  hot  water,  neutralize  and 
then  add  twelve  times  the  quantity  of  hydrogen  peroxide  (3  per  cent  solu- 
tion) as  dyestuff.  Steep  the  skins  in  this  solution  until  the  fur  has  assumed 
the  desired  shade.  Instead  of  hydrogen  peroxide,  sodium  perborate  may 
be  used,  in  which  case  one-half  the  quantity  of  perborate  as  dyestuff  is 
taken.  Immediately  before  use  the  perborate  is  neutralized  with  formic 
acid. 

Many  different  shades  may  be  obtained  on  furs  with  the  use  of  these 
dyes  by  using  various  mordants  either  alone  or  in  combination  with  one 
another.  Copperas,  bluestone,  and  chrome  may  be  used,  but  it  must  be 
remembered  that  chrome  and  copperas  cannot  be  mixed  together,  though 
all  other  combinations  of  these  three  may  be  made.  Tartar  is  recom- 
mended as  an  addition  to  the  mordanting  bath;  for  10  gallons  of  mordant- 
ing solution  use  5  ozs.  of  chrome,  bluestone  or  copperas  with  2|  ozs. 
of  tartar.  This  is  a  strong  enough  mordant  for  the  heaviest  shades  or 
even  black,  and  for  the  lighter  shades  it  may  be  proportionately  diluted. 
For  the  production  of  blacks  it  is  well  to  use  some  copper  sulphate. 


634  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

After  dyeing  furs,  especially  in  the  case  of  hea^y  shades,  the  skins 
should  be  washed  in  lukewarm  water  and  then  to  remove  adhering  unfixed 
dyestuff  wash  in  a  weak  cold  soap  solution.  This  also  prevents  the  ten- 
dency of  the  color  in  heavy  shades  of  coming  up  bronzy. 

A  field  of  fur  dyeing  in  which  fancy  colors  are  often  used  is  the  dyeing 
of  sheep,  goat  and  angora  skins  for  use  as  rugs.  For  this  purpose  basic 
dyes  may  be  used  in  a  weak  soap  bath  at  110°  F.  In  order  to  preserve  the 
flesh  part  of  the  skin  from  being  dyed  it  is  first  coated  with  tallow  or  a 
mixture  of  fat  having  a  higher  melting-point  than  the  temperature  of  the 
dyebath,  or  paper  may  be  pasted  on  the  flesh  side  and  removed  after  dyeing. 
When  the  hair  is  hard  and  stiff  and  will  not  absorb  the  dyestuff  readily  the 
skins  must  be  chlorinated  by  steeping  the  hair  portion  of  the  skins  first  in  a 


Fig.  288.— Cloth  Doubling  and  W  Hiding  Machine.     [Parks  &  Woolson.) 

solution  containing  1  gallon  of  h3'drochloric  acid  per  100  gallons  of  water. 
This  bath  should  be  used  cold  for  fifteen  minutes.  Then  without  rinsing 
place  in  a  bath  containing  the  clear  solution  from  10  ozs.  of  chloride  of  lime 
in  10  gallons  of  water;  use  cold  for  one  hour,  then  run  through  the  first 
acid  bath  again  for  fifteen  minutes.  Rinse  in  lukewarm  water  containing 
a  small  quantity  of  sodium  hyposulphite  or  sodium  bisulphite  for  the  pur- 
pose of  neutralizing  the  last  traces  of  chlorine. 

For  the  dyeing  of  skins  the  acid  colors  may  also  be  used,  in  which  case 
the  dyebath  is  made  up  with  the  addition  of  2  to  5  per  cent  of  acetic  acid. 
After  dyeing  and  rinsing  it  is  well  to  soften  the  hair  by  treating  the  skin  in  a 
bath  containing  1  lb.  of  oHve  oil  soap,  2  ozs.  of  ohve  oil  and  1  oz.  of  ammonia 
to  10  gallons  of  water.  After  steeping  in  this  liquor  for  fifteen  minutes 
hydro-extract  and  dry  without  rinsing. 


FEATHER  DYEING  635 

4.  The  Dyeing  of  Feathers. — Feathers  consist  of  animal  tissue  of  a 
nature  very  similar  to  that  of  wool,  and  they  react  with  dyestuffs  in  much 
the  same  manner  as  that  fiber.  It  must  be  remembered,  however,  that 
feathers  consist  of  two  parts,  the  fine  fibrous-like  portion  and  the  hard 
quill,  which  is  of  a  horn-like  tissue;  also  the  quahty  and  properties  of 
feathers  differ  very  widely  in  their  origin  from  the  soft,  delicate  ostrich 
plume  to  the  hard,  stiff  goose-quill.  Many  feathers  are  also  possessed  of  a 
natural  color  which  often  varies  through  a  wide  range  of  shades  even  in 
the  same  class  of  feathers.  The  feathers  that  are  mostly  dyed  are  the 
natural  white  feathers,  though  at  times  colored  feathers  are  also  dyed, 
chiefly  to  a  black  color. 

The  principal  dyes  employed  for  feathers  are  the  acid  colors  and  to  a 
much  smaller  extent  the  basic  colors.*  Before  dyeing  it  is  necessary  to 
clean  the  feathers  of  the  miscellaneous  dirt  and  the  natural  grease  they 
contain,  and  this  is  generally  done  with  a  lukewarm  (100  to  120°  F.) 
weak  solution  of  soap  or  ammonia  or  ammonium  carbonate.  Sometimes 
the  cleansing  is  done  in  cold  water  containing  a  little  soda  ash  and  some 
powdered  starch.  After  scouring,  the  feathers  should  be  well  rinsed  in 
lukewarm  water.  In  the  treatment  of  feathers  care  should  be  taken  not 
to  have  the  solutions  too  hot  or  too  strongly  alkaline,  as  these  conditions 
would  much  unpair  the  quality  of  the  material. 

In  addition  to  cleansing,  it  is  also  frequently  necessary  to  bleach  feath- 
ers, either  to  obtain  a  good  wliite  color  or  for  the  purpose  of  subsequently 
dyeing  a  dehcate  bright  shade.  This  may  be  best  done  by  using  a  bath  of 
hydrogen  peroxide  in  a  manner  similar  to  the  bleaching  of  wool  or  silk. 
SometuTies  a  satisfactory  bleaching  may  be  done  with  hydrosulphites 
(Hyraldite,  Blankit,  etc.).t 

In  dyeing  with  acid  colors  the  feathers  are  treated  in  a  bath  for  one  to 
two  hours  just  under  the  boil  with  the  requisite  amount  of  well-dissolved 
acid  dyestuff  together  with  2  to  5  per  cent  of  sulphuric  acid  (or  10  to  15 
per  cent  of  sodium  bisulphate).  As  the  material  of  the  feather  is  rather 
difficult  to  penetrate  it  is  well  to  employ  only  those  dyes  having  good 
levehng  properties  and  also  to  add  the  dyestuff  solution  in  several  portions 
to  the  bath,  also  do  not  use  too  short  a  bath. J     After  dyeing  the  feathers 

*  Substantive  colors  are  seldom  used  for  the  dyeing  of  feathers,  as  the  shades  are 
rather  dull  for  this  class  of  work. 

t  Bed  feathers  may  be  bleached  with  hydrosulphites  as  follows  (Badische) :  Pour 
fresh  water  over  the  well-washed  feathers,  and  add  in  portions  while  stirring  slowly  and 
constantly  5  per  cent  of  Blankit  on  the  weight  of  the  feathers.  Leave  the  material  for 
one  to  two  hours  in  the  bleaching  bath  stirring  up  every  now  and  then  with  a  wooden 
stick.  Then  rinse  in  pure  water,  hydro-extract  and  steam.  The  hydrosulphite  solution 
may  be  used  for  bleaching  further  lots  by  freshening  up  with  1  to  3  per  cent  of  Blankit. 

t  Wherever  possible  it  is  best  to  use  a  rotary  dyeing  machine  for  the  dyeing  of  feath- 
ers, though  where  dyeing  small  lots  (especially  fancy  feathers)  the  dyebath  is  usually 
made  up  in  pails  or  small  dyevats. 


636  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

are  well  rinsed  first  in  cold  water  and  then  in  water  containing  a  small 
quantity  of  sulphuric  acid.  In  dj-eing  with  colors  like  Eosin,  Phloxine, 
Alphanol  Blue,  etc.,  use  a  small  amount  of  acetic  acid  in  the  bath  in  place 
of  sulphuric  acid.  After  rinsing  the  feathers  are  dried  in  a  rotating  ma- 
chine and  usually  mixed  up  with  sawdust  of  powdered  starch. 

In  dyeing  blacks  such  colors  as  Feather  Black,  Acid  Black,  Wool 
Black,  Naphthylamine  Black,  etc.,  are  employed,  using  as  short  a  bath  as 
possible,  containing  6  to  10  ozs.  of  the  dyestuff  and  1|  to  2  ozs.  of  sulphuric 
acid  per  10  gallons  of  hquor  and  dyeing  at  the  boil  for  one  to  two  hours. 
Ostrich  feathers  may  be  dyed  black  with  10  to  16  ozs.  of  dyestuff  and  3  to  4 
ozs.  of  formic  acid  per  10  gallons  of  liquor.  A  good  black  may  also  be 
obtained  by  dyeing  with  Anthracene  Acid  Black  with  the  addition  of  1  to  2 
per  cent  of  formic  acid,  boiling  for  one  hour,  then  mordanting  for  one  to 
two  hours  in  a  fresh  boiling  bath  with  3  per  cent  of  chrome  and  3  per  cent 
of  bluestone  and  1  per  cent  of  formic  acid;  then  rinse  and  top  in  a  boiling 
bath  with  Logwood  and  Fustic  extract.  After  dj'eing  brighten  in  a  hot 
soap  bath  containing  a  little  oil. 

In  dyeing  basic  colors  on  feathers  use  a  weak  soap  bath  at  100°  F.  in 
the  case  of  light  shades.  When  hea\y  shades  are  to  be  dyed  add  to  the 
bath  3  to  5  per  cent  of  acetic  acid  and  dye  at  175°  F.  Only  the  following 
basic  colors  are  well  suited  for  feather  dyeing: 

Rhodamine  B  and  G  Bismarck  Brown 

Methyl  Violet  B  Brilliant  Green 

Magenta  Auramine 

Janus  Dyes  Methylene  Blue 

5.  The  Dyeing  of  Straw. — Straw  is  essentially-  a  vegetable  fiber  but  it  is 
covered  with  a  hard  silicious  tissue  and  usually  has  a  pronounced  yellowish 
color.  Before  dyeing  it  is  necessary  to  scour  the  material  in  order  to 
remove  the  waxy  and  fatty  matters  and  dirt  and  also  to  soften  up  and  wet- 
out  the  fiber  so  that  the  dyestuff  solution  may  penetrate.*  In  the  case  of 
light  and  bright  shades  it  will  also  be  necessary  to  bleach  the  straw  so  as  to 
remove  most  of  the  yello\vish  or  brownish  color  of  the  natural  fiber.  The 
straw  may  be  scoured  by  boiling  in  a  soap  bath  containing  a  small  amount 
of  soda  ash  and  then  rinsing.  For  the  purpose  of  wetting-out  the  material 
it  should  be  steeped  for  several  hours  (or  overnight)  in  boiling  water  or  in  a 
solution  of  sodium  bisulphite  of  1  to  3°  Tw.  Bleaching  straw  is  usually 
done  by  stoving  (treating  with  sulphur  dioxide  gas)  or  by  steeping  in 
a  solution  of  hydrogen  peroxide.     Another  method  of  bleaching  is  to 

*  For  the  wetting-out  of  straw  and  straw-braid  it  is  recommended  to  boil  the  material 
for  two  hours  in  water  containing  h  lb.  of  sodium  acetate  per  100  lbs.  of  straw.  While 
th3  sodium  acetate  materially  assists  in  the  boiling-out  of  the  goods  it  also  makes  the 
straw  more  yellow  in  color.  The  use  of  a  small  amount  of  tartaric  acid  in  boiling-out 
has  a  contrary  effect,  giving  a  lighter  color  to  the  material. 


STRAW  DYEING  637 

use  a  bath  containing  10  gallons  of  water,  1|  lbs.  of  oxalic  acid  and  then 
slowly  adding  with  constant  stirring  1  lb.  of  sodium  peroxide  and  then  1^ 
lbs.  of  silicate  of  soda  so  that  the  bath  shows  an  alkaline  reaction  with  lit- 
mus paper.  Steep  in  this  bath  until  the  yellow  tint  is  removed.  Then 
rinse  in  a  weak  solution  of  tartaric  acid  (or  in  a  bath  containing  1  oz.  of 
sulphuric  acid  to  4  gallons  of  water),  and  finally  washing  well  in  fresh 
water.* 

The  classes  of  dyes  employed  for  straw  and  straw-plait  are  the  basic, 
acid  and  substantive  colors.  The  first  are  mostly  used  for  bright  full 
shades  and  blacks  on  material  that  is  easy  to  penetrate,  while  the  acid  dyes 
are  used  for  all  manner  of  colors  and  on  straw  that  is  more  difficult  to 
penetrate;  the  substantive  dyes  are  used  mostly  for  blacks. 

In  dyeing  with  the  basic  colors  the  well-wetted  and  still  hot  material 
is  placed  in  a  lukewarm  dyebath  containing  2  to  5  per  cent  of  acetic  acid 
and  dyed  at  a  gently  boiling  temperature  for  two  to  three  hours.  Good 
penetration  of  color  may  be  facilitated  by  increasing  the  amount  of  acetic 
acid  in  the  bath.  In  the  case  of  dark  shades  it  is  well  to  allow  the  material 
to  cool  down  in  the  dyebath  overnight.! 

The  acid  dyes  are  applied  to  straw  in  a  concentrated  bath  with  the  addi- 
tion of  some  acetic  acid  and  boiling  for  three  to  four  hours.  The  acid 
dyes  are  not  very  well  taken  up  by  the  fiber  and  hence  the  baths  do  not 
exhaust. 

The  substantive  dyes  (it  is  seldom  that  any  other  dye  but  black  is 
used  in  this  case)  are  applied  in  a  neutral  boiling  concentrated  bath,  or  in  a 
bath  containing  5  per  cent  of  soap. 

Two-color  effects  may  be  obtained  on  split  straw  by  dyeing  the  material 
first  with  Sulphur  Black,  Sulphur  Brown,  Sulphur  Green  or  Sulphur  Blue, 
using  a  bath  containing  1  to  3  lbs.  of  the  sulphur  color  and  an  equal  quan- 
tity of  sodium  sulphide  to  10  gallons  of  hquor ;  dye  for  twenty  minutes  at 
70°  F.  To  the  bath  may  also  be  added  8  ozs.  of  soda  ash  and  2  lbs.  of  glau- 
bersalt.  The  dyeing  must  be  carried  out  quickly,  and  then  the  goods  are 
rinsed  off  well  in  cold  and  lukewarm  water,  and  if  the  split  is  to  be  left  white 
steep  for  one  hour  at  175°  F.  in  a  bath  containing  4  ozs.  of  sulphuric  acid 
and  4  ozs.  of  sodium  bisulphite  (G4°  Tw.),  and  finally  rinse  well.     Or  if 

*  Straw  may  also  be  bleached  with  hydrosulphite  compounds,  such  as  Blankit,  in 
combination  with  hydrogen  peroxide,  as  follows  (Badische) :  Steep  the  material  for 
several  hours  in  the  peroxide  bath  (prepared  as  described  above),  rinse  and  steep  for 
several  hours  in  a  cold  bath  containing  10  lbs.  of  Blankit  per  100  gallons  of  water.  Rinse 
well  and  dry  at  a  low  temperature.  The  hydrosulphite  bath  may  be  used  for  further 
lots  by  freshening  with  one-third  the  original  quantity  of  Blankit. 

t  To  obtain  well-penetrated  colors  with  the  basic  dyes  add  all  of  the  acid  at  the 
beginning  and  add  the  dye  solution  in  several  portions.  Where  Auramine  is  employed 
with  other  colors  it  must  be  added  only  after  the  boiling  is  finished,  as  this  dye  is  decom- 
posed at  a  boiling  temperature. 


638 


APPLICATION  OF  DYES  TO  VARIOUS   MATERIALS 


a  two-color  effect  is  to  be  produced  over-dye  the  straw  with  a  suitable 
acid  color  in  the  manner  already  described. 

In  wetting-out,  scouring,  dyeing,  or  bleaching  of  straw  materials  the 
water  employed  should  be  as  soft  as  possible,  for  if  water  is  used  con- 
taining luue  salts  the  latter  combine  with  the  silicious  compounds  of  the 
straw  to  form  a  sort  of  water-resisting  cement  which  seriously  impedes 
the  action  and  penetration  of  the  solutions  used. 

6.  The  Dyeing  of  Wood  Chip  and  Plait. — This  material  differs  some- 
what from  straw  in  that  it  consists  of  strips  of  wood,  thin  and  tough,  but 
more  brittle  than  straw.  It  is  used  for  the  manufacture  of  hat  materials, 
baskets,  etc.  Before  dyeing  the  material  must  first  be  well  wetted-out 
in  water.     For  dyeing  bright  shades  the  basic  dyes  are  used,  while  the  acid 


Fig.  289. — Cloth-inspecting  Machine  with  Cradle,  Reverse  Motion,  and  Rolling  Head. 

(Curtis  &  Marble.) 

dyes  are  employed  for  light,  clear  colors,  and  some  of  the  substantive  colors 
are  used  for  dyeing  deep  shades  and  blacks  on  goods  that  are  difficult  to 
penetrate.  The  basic  colors  are  dyed  in  the  same  manner  as  for  straw. 
The  acid  colors  are  apphed  in  a  dilute  hquor  at  the  boil  for  one  hour  with 
the  addition  of  2  to  5  per  cent  of  acetic  acid,  and  subsequent!}^  rinsing  the 
goods  thoroughly  and  drying  at  a  moderate  temperature.  The  sub- 
stantive colors  are  dyed  at  the  boil  for  one  to  two  hours  with  the  addition 
of  5  to  20  per  cent  of  glaubersalt  (desiccated) ,  and  if  the  material  is  diffi- 
cult to  penetrate  add  1  per  cent  of  soda  ash  or  borax.*  WTien  acid  is  used 
in  any  solution  for  dyeing  wood  chip  the  material  must  subsequently 
be  washed  very  thoroughly  to  remove  all  trace  of  acid,  as  otherwise  the 
chip  will  develop  brittleness  on  drying.  The  sulphur  dyes  may  also  be 
used  on  this  material,  oftentimes  with  good  advantage  for  the  production 

*  In  order  to  obtain  the  maximum  depth  of  shade  with  any  class  of  dyestuff  it  is 
well  to  allow  the  material  after  dyeing  to  steep  for  one  to  two  hours  in  the  cooling  bath. 


DYEING  HAIR  AND  BRISTLES  639 

of  fast  shades.  After  dyeing  with  the  sulphur  colors  the  wood  chip  should 
be  well  washed  and  then  acidulated  with  acetic  acid  in  a  dilute  bath. 
The  colors  may  be  brightened  by  topping  with  the  basic  dyes.  By  this 
method  shades  of  good  fastness  to  light  may  be  produced. 

Wooden  match  sticks  are  mostly  dyed  with  Rhodamine  or  Eosin. 
Fast  Green  also  is  sometimes  used  for  this  purpose. 

7.  The  Dyeing  of  Horse-hair  and  Bristles. — These  are  animal  fibers 
closely  analogous  to  wool  in  their  general  characteristics  and  dyeing 
properties.  Physically,  however,  they  are  much  harder  and  more  resistant 
to  the  penetration  of  dyes  and  solutions.  The  material  must  first  be  well 
cleaned  by  scouring  in  a  lukewarm  bath  with  2  to  3  ozs.  of  soda  ash  or 
ammonia  or  ammonium  carbonate  and  8  ozs.  of  soap  per  10  gallons  of  liquor. 
After  scouring  the  goods  are  well  washed  to  remove  all  soapy  residues. 

The  principal  colors  used  for  the  dyeing  of  horsehair  and  bristles  are 
the  acid  dyes,  but  not  all  of  the  acid  dyes  are  suited  to  this  purpose.  Those 
best  adapted  are  the  following: 

Acid  Black  4BL  Formyl  Violet  S4B 

Acid  Green  Indian  Yellow  R 

Agalm  I  Black  Orange  extra 

Alizarine  Blue  SAP  •  Naphthylamine  Black 

Azo  Rubine  A  Palatine  Black 

Brilliant  Croceine  Phenylamine  Black  4B,  T 

Cyanole  extra  Roccelline 
Formyl  Blue  B 

These  dyes  are  applied  in  a  bath  containing  2  to  3  per  cent  of  sulphuric 
acid,  starting  at  120°  F.,  gradually  raising  to  the  boil  and  boiling  for  one 
hour.*  When  dyeing  blacks  it  is  best  to  add  the  dyestuff  solution  to  the 
bath  in  several  portions  in  order  to  obtain  better  penetration.  After 
dyeing  the  goods  are  lustered  by  treating  with  a  lukewarm  soap  bath.  A 
black  may  also  be  obtained  by  using  the  substantive  dye  Direct  Deep 
Black  E,  EW,  dyeing  at  the  boil  for  one  hour  with  the  addition  of  20  per 
cent  of  glaubersalt  and  2  per  cent  of  soda,  and  then  adding  2  per  cent  of 
acetic  acid  and  continuing  the  boiling  for  one-half  hour. 

Cow-hair  felts  may  be  dyed  in  the  same  general  manner  as  horse- 
hair. 

8.  The  Dyeing  of  Human  Hair. — The  human  hair  referred  to  in  this 
connection  is  not  that  growing  on  the  heads  of  living  persons,  but  the 
hair  that  is  brought  into  trade  for  the  making  of  plaits,  wigs,  switches,  and 
toupes.  This  hair  is  mostly  obtained  from  China,  Japan,  and  Russia  and 
is  usually  black  in  color.     The  variety  of  colors  to  be  obtained  on  hair  are 

*  For  the  production  of  very  fast  colors  the  after-chromed  acid  dyes  are  suitable. 
Some  of  the  substantive  dyes  may  also  be  used. 


640  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

naturally  somewhat  limited,  consisting  of  various  shades  of  brown  for  the 
most  part,  though  graj-  and  even  red  colors  are  sometimes  required. 

Owing  to  the  black  color  of  the  natural  product  it  is  necessarj^  to  first 
])leach  the  hair  before  it  can  be  dyed.  Tliis  is  usually  done  with  a  solution 
of  hydrogen  peroxide  or  sodium  perborate.  First  the  hair,  which  is 
usually  very  dirty,  is  scoured  in  a  bath  containing  10  gallons  of  water,  8  ozs. 
potassium  carbonate,  ^  lb.  of  sodimu  perborate  and  1  to  2  lbs.  of  soap,  using 
a  lukewarm  bath  (120°  F.)  and  leaving  the  hair  overnight  in  the  cooling 
bath.  Then  wash  well  in  soft  water,  and  the  hair  should  then  possess  a 
chestnut-brown  color.  It  must  now  be  further  bleached  with  hydrogen 
peroxide  (or  sodium  peroxide) ,  the  bleaching  bath  containing  about  1  part 
of  hydrogen  peroxide  (12  vols.)  with  2  parts  of  water.  The  goods  are 
steeped  in  this  solution  at  a  temperature  of  140°  F.  and  then  left  overnight. 
Afterwards  they  are  well  washed  in  a  bath  containing  a  small  amount  of 
oxalic  acid.  The  bleaching  may  also  be  carried  out  with  the  use  of  sodium 
perl)orate,  as  follows:  Dissolve  2  lbs.  of  sodium  perborate  in  10  gallons  of 
water  at  70°  F.  and  add  suflBcient  sulphuric  acid  to  give  a  slight  acid  reac- 
tion with  litmus  paper  (this  is  for  the  purpose  of  neutralizing  the  caustic 
alkali  that  is  Hberated  when  the  perborate  is  dissolved  in  the  water); 
then  bring  the  bath  to  a  slightly  alkahne  condition  by  the  addition  of 
ammonia.  The  well-scoured  hair  is  entered  in  tliis  solution  at  85°  F.; 
the  temperature  is  gradually  raised  to  165°  F.  and  the  goods  are  left 
immersed  in  the  liquor  for  one  to  two  days. 

After  the  hair  is  bleached  it  is  soured  in  a  bath  for  a  few  hours  containing 
10  lbs.  of  nitric  acid  per  10  gallons  of  water,  and  then  well  rinsed  in  fresh 
water  and  dried  at  a  moderate  temperature. 

Oriental  hair  is  considerably  coarser  than  the  hair  of  Americans  or 
Europeans,  and  tliis  requires  that  the  hair  be  reduced  in  diameter.  This 
is  done  between  the  bleacliing  and  the  souring  with  nitric  acid  bj''  steeping 
the  goods  in  a  solution  of  chloride  of  lime  of  0.2°  Tw.  for  about  two 
days.  This  makes  the  hair  tliinner  and  also  gives  it  a  high  luster.  After 
tliis  treatment  the  hair  is  well  washed,  and  then  soured  \\-ith  nitric 
acid. 

For  the  dj-eing  of  human  hair  the  acid  colors  are  largelj'  used,  especialty 
those  which  are  fast  to  light,  such  as  Acid  Yellow  AT,  Alizarine  Sapphire, 
Orange  GG,  Ponceau  4GB,  etc.  Also  the  chrome  dyeing  colors  may  be 
used  (the  chromate  or  mono-chrome  djTs).  The  acid  colors  are  dj-ed  in  a 
bath  containing  5  per  cent  of  glaubersalt  and  1  per  cent  of  sulphuric  acid, 
starting  lukewarm  and  raising  to  the  boil  for  one-quarter  hour.  The 
chrome  colors  are  dj-ed  with  the  adcUtion  of  one-half  the  weight  of  chrome 
as  of  dyestuff,  starting  at  110°  F.,  gradually  raising  to  the  boil,  and  after 
dyeing  for  one-half  hour  adding  2  to  3  per  cent  of  acetic  acid  to  exhaust 
the  bath.     Colors  obtained  in  this  manner  are  fast  to  light,  wear,  per- 


DYEING  ARTIFICIAL  FLOWERS  641 

spiration,  and  washing.  By  proper  combination  of  the  dyestuffs  avail- 
able suitable  shades  of  brown,  etc.,  may  be  produced. 

Para-phenylene-diamine  and  amino-phenol  are  also  used  for  the  dj^eing 
of  fast  dark  brown  shades  on  hair  in  the  same  manner  as  for  fur.  The 
natural  dye  Henna  is  also  extensively  employed  for  this  purpose. 

9.  The  Dyeing  of  Artificial  Flowers. — Artificial  flowers  are  made  from 
various  fabrics  consisting  of  cotton,  silk,  satin  (silk-cotton  goods)  and 
velvets  as  well  as  paper.  The  various  parts  of  the  flowers  are  cut  out  of 
the  cloth  by  means  of  suitably  shaped  dies,  and  from  these  the  flowers  are 
built  up  by  the  deft  handling  of  skilled  workers.  For  some  purposes  the 
cloth  is  dyed  in  the  piece  previous,  to  cutting  up,  and  this  is  especially 
true  in  case  very  brilliant  colors  are  required.*  For  most  purposes,  how- 
ever, the  cut  pieces  are  dyed  either  in  small  packages  or  single,  or  in  some 
cases  by  means  of  an  air  spray.  Considerable  skill  and  ingenuity  must  be 
exercised  in  order  to  obtain  the  proper  shading  and  blending  of  the  colors 
to  imitate  the  natural  coloring  of  the  flowers. 

The  dyes  employed  for  this  purpose  are  those  soluble  in  alcohol,  though 
sometimes  the  dye  is  used  dissolved  in  water  and  the  solution  diluted  with 
an  equal  volume  of  alcohol.  The  object  of  using  an  alcohol  solution  is  to 
have  the  dye  in  a  form  in  which  it  will  dry  quickly  on  the  cloth.  The  fol- 
lowing dyes  are  soluble  in  alcohol  and  are  suitable  to  this  method  of  appli- 
cation : 

Auracine   G-  Methyl  Violet 

Auramine  Methylene  Blue 

Bismarck  Brown  Methylene  Green 

Brilliant  Green  Methylene  Violet 

Chrysoidine  New  Methylene  Blue 

Crystal  Violet  Nigrosine  (spirit  sol.) 

Diamond  Fuchsine  Phosphine 

Eosin  Rhodamine  B,  C 

Indazine  (spirit  sol.)  Safranine 

Irisamine  G  Tannin  Heliotrope 

Janus  Dyes  Thioflavine  R 

Lake  Black  Vesuvine 

Magenta  Victoria  Blue 

The  dye  solution  is  prepared  by  dissolving  from  1  to  16  ozs.  of  the  dye- 
stuff  in  1  gallon  of  lukewarm  alcohol  and  the  dyeing  is  done  by  dipping  the 
cut  forms  of  cloth  into  the  cold  or  lukewarm  solution,  squeezing,  then  rub- 
bing with  a  little  oil  or  glycerin  and  drying. 

Among  the  water-soluble  dyes,  the  acid  colors  are  the  principal  ones 
employed,  though  a  few  of  the  substantive  dyes  may  also  be  used  with 
satisfaction.     It  must  be  always  borne  in  mind  that  the  colors  for  arti- 

*  Where  considerable  fastness  to  light  is  desired  it  is  best  first  to  mercerize  the  cloth 
with  caustic  soda,  bleach  with  chloride  of  lime,  and  dye  with  the  acid  colors. 


642  APPLICATION   OF  DYES  TO  VARIOUS  MATERIALS 

ficial  flowers  must  be  bright  and  clear  in  tone  and  hence  only  the  bright- 
est acid  dyes  are  suitable  for  the  purpose.  The  following  acid  dyes  are 
those  mostly  employed: 

Acid  Green  2G  Metanil  Yellow 

Acid  Violet  4B  Naphthol  Green  B 

Acid  Yellow  AT  Naphthol  Yellow  S 

Alkali  Blue  New  Patent  Blue 

Brilliant  Milling  Green  B  Orange  ENZ 

Brilliant  Croceine  Rosazeine 

Eosin  Rose  Bengale 

Erythrosine  Tartrazine 

Formyl  Violet  S4B  ,  Water  Blue 

Indian  Yellow 

and  the  following  substantive  dyes: 

Benzo  Fast  Black  Benzopurpurin  4B 

Benzo  Green  G  Pluto  Black  BS 

Benzo  Sky  Blue 

The  required  dyestuff  is  dissolved  in  warm  water  and  then  diluted  with 
an  equal  volume  of  alcohol.  It  is  also  recommended  to  add  some  acetic 
acid  or  alum  (4  ozs.  per  10  gallons  of  solution). 

Varied  colored  effects  may  be  produced  by  clipping  first  in  a  solution  to 
produce  a  light  shade  and  then  dipping  again  in  a  solution  of  another  color. 
Very  effective  results  are  also  obtained  by  using  the  air-brush  (aerograph) 
with  an  alcoholic  solution  of  the  dyestuff,  as  in  tliis  manner  the  color  ma}- 
be  sprayed  wherever  desired  and  delicate  shading  and  blends  may  be 
obtained;  also  pattern  effects  may  be  produced  with  the  aid  of  stencils 
and  the  air-brush.  In  some  cases  it  is  necessary  to  use  insoluble  color- 
lakes  and  these  are  applied  in  a  medium  of  starch  paste. 

Natural  flowers  are  sometimes  colored  artificially,  the  freshly  cut  flowers 
with  the  stem  being  used.  The  acid  colors  are  mostly  used  in  the  form  of  a 
very  dilute  solution  in  pure  soft  water  (distilled  water  is  best) ,  the  flowers 
being  simply  dipped  in  these  solutions  and  the  color  is  absorbed  through 
the  plant  tissues  by  capillary  action.  By  using  white  or  light-colored 
flowers  and  by  properly  selecting  the  dyestuffs  peculiar  and  odd  effects 
may  often  be  produced  in  this  manner.  The  dyes  chiefly  recommended 
for  this  purpose  are 

Acid  Magenta  Fast  Acid  Yellow 

Cyanole  Orange  II 

Acid  Green  Acid  Violet 

Natural  leaves  and  grasses  and  palm  fronds  are  also  dyed  for  the  pro- 
duction of  the  so-called  "  everlasting  "  plants,  largely  used  for  decorative 
purposes  and  for  funeral  wreaths.     These  are  mostly  dyed  with  basic 


METHODS  FOR   DYEING   WOOD  643 

colors  in  a  water  solution  with  the  addition  of  a  small  quantity  of  glycerin 
and  some  acetic  acid,  the  dyeing  being  carried  out  at  the  boil.  After 
dyeing  the  goods  are  steeped  for  some  time  in  a  solution  of  1  to  2  lbs.  of 
glycerin  to  1  gallon  of  water;  or  the  leaves  are  steeped  in  a  solution  of 
magnesium  chloride  (or  calcium  chloride)  of  15°  Tw.  with  the  addition  of  a 
small  amount  of  emulsified  oil,  and  then  dried  in  the  air.* 

10.  The  Dyeing  of  Wood. — Wood  may  be  dyed  by  two  methods;  in 
one  the  color  solution  is  simply  brushed  on  and  allowed  to  penetrate  as 
far  as  possible  into  the  fiber  of  the  material.  Either  a  solution  in  water 
or  alcohol  may  be  used  and  only  the  most  soluble  dyes  are  employed.  By 
this  method  it  is  only  possible  to  obtain  a  rather  superficial  dyeing  of  the 
surface,  as  the  color  will  not  penetrate  to  any  great  depth.     It  is  possible. 


Fig.  290.— Two-cylinder  Teasel  Gig.     (Parks  &  Woolson.) 

however,  by  this  means  to  dye  veneers  or  thin  split  wood.  Sometimes, 
instead  of  brusliing  on  the  solution  the  wood  is  steeped  in  the  dye  solution 
which  may  be  employed  either  hot  or  cold.  The  second  metho.d  of  dyeing 
wood  is  to  place  the  material  in  the  dye  liquor  in  a  pressure  tank  and  the 
apparatus  is  then  put  under  a  high  pressure  (80  to  120  atmospheres)  for 
a  period  of  two  to  twelve  hours  without  heating.  By  this  means  large 
pieces  of  wood  may  be  dyed  throughout  and  with  very  uniform  colors. 
Better  results  are  obtained  if  the  air  is  removed  from  the  wood  first  by 
heating  it  in  a  vacuum  chamber  and  then  forcing  in  the  dye  solution. 
Usually  this  is  carried  out  in  the  same  apparatus  as  employed  for  the 
pressure  dyeing. 

In  dyeing  wood  by  the  brushing  or  steeping  method  those  basic,  acid 

*  This  treatment  is  for  the  purpose  or  making  the  goods  soft  and  pliable,  otherwise 
on  drjdng  the  material  would  become  brittle  and  lifeless. 


644  APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 

or  substantive  dyes  which  are  fast  to  hglit  are  principally  employed. 
Dyes  of  good  solubility  arc  also  of  importance  in  this  connection.  For 
some  purposes  dyestuffs  soluble  in  alcohol  are  used,  in  which  case  the  basic 
colors  are  employed.  For  the  dyeing  of  wood  surfaces  in  connection  with 
varnishes  special  products  of  spirit  soluble  dyes  are  manufactured.  Some 
of  the  dyes  which  are  insoluble  in  water  (and  hence  useless  for  the  ordinary 
purposes  of  dyeing)  are  used  for  this  process ;  also  spirit-soluble  lakes  made 
by  precipitating  certain  dyes  with  rosin  soap  are  used. 

In  dyeing  wood  by  the  pressure  impregnation  method  the  easily  soluble 
acid  dyes  and  some  of  the  basic  dyes  are  used.  Pure  water  must  be  used 
for  the  solutions  and  they  should  be  carefully  filtered  to  obtain  as  perfect  a 
solution  as  possible. 

11.  The  Dyeing  of  Celluloid. — Celluloid  is  dyed  in  two  forms,  either 
during  the  process  of  manufacture  when  the  celluloid  material  is  still 
in  the  dough  form  and  the  dyes  or  their  solutions  are  simply  incorporated 
with  the  mass  and  worked  in;  or  the  celluloid  may  be  dyed  when  manu- 
factured in  the  form  of  films,  in  which  case  alcohol  solutions  of  the  dyes  are 
employed.  For  dyeing  the  celluloid  dough  either  coal-tar  color-lakes  or 
mineral  dyes  may  be  employed  or  spirit  solutions  of  suitable  dyes  may  be 
used  which  will  amalgamate  with  the  celluloid  mass.  By  processes  of 
mixing  and  blending  the  celluloid  various  color  effects  may  be  obtained 
for  the  production  of  fancy  articles. 

For  the  dyeing  of  celluloid  films  spirit-soluble  colors  are  used  as  the 
celluloid  is  not  penetrated  by  water  solutions.  The  following  dyes  are 
suitable  for  this  purpose: 

Aiirainine  Metanil  Yellow 

Bismarck  Brown  Methyl  Violet 

Brilliant  Croceine  R  Methylene  Blue 

Brilliant  Green  Methylene  Green 

China  Green  Naphthaline  Yellow 

Chrysoidine  Nigrosine  (sjjirit  sol.) 

Crystal  Violet  Quinoline  Yellow 

Cyanosine  Rhodamine  B,  G 

Eosin  Rhoduline  Violet 

Irisamine  G  Rosazeine 

Janus  Dyes  Safranine 

Lake  Black  Si)irit  Blue 

Magenta  Tropaeoline  G 

Malachite  Green  Victoria  Blue 

Marine  Green  Victoria  Yellow 

The  dyestuff  is  dissolved  in  alcohol  (use  95  to  98  per  cent)  at  140  to 
160°  F.,  and  the  goods  are  dyed  by  steeping  them  in  the  solution  or  by 
spraying  with  the  air-brush.  When  deep  colors  are  dyed  it  is  advised 
to  rub  the  material  with  a  little  vaseline  after  dyeing. 


DYEING   BUTTON   MATERIALS  645 

For  the  dyeing  of  picture  films  containing  a  gelatin  film  on  a  celluloid 
base,  and  when  the  gelatin  surface  only  is  to  be  colored,  the  easily  soluble 
acid  dyes  may  be  used  in  a  water  solution.  The  dyes  are  dissolved  hot  and 
well  filtered,  and  the  dyeing  is  carried  out  by  dippi-^g  in  the  cold  solution 
to  whrch  a  little  acetic  acid  may  be  added.  As  the  gelatin  is  very  absorp- 
tive of  dye  solutions,  good  colors  may  also  be  ol)tained  by  using  various 
basic  dyes  or  many  of  the  substantive  colors,  and  if  proper  care  is  exer- 
cised, the  dyebaths  may  be  used  warm  in  order  to  obtain  good  penetration 
and  development  of  the  color.  After  dyeing  the  material  should  be  well 
rinsed  in  running  water  and  then  carefully  dried  in  the  air.  Rapid  drying 
in  hot  air  is  to  be  avoided, 

12.  Th3  Dyeing  of  Button  Material. — Buttons  are  made  from  a  variety 
of  matarials,  the  principal  product  used,  perhaps,  being  what  is  known  as 
Vegetable  Ivory.  This  is  a  hard  nut  (Corozo)  obtained  in  South  and 
Central  America.  It  is  a  hard  ivory-like  material,  white  in  color  with  a 
slight  yellowish  tint,  and  consists  of  hardened  vegetable  tissue  containing 
also  substances  of  a  nitrogenous  character.  Horn  and  mother-of-pearl  are 
also  used  extensively  for  the  manufacture  of  buttons,  and  to  a  lesser  extent, 
ivory.  Synthetic  plastics  such  as  Gallalith,  Bakelite,  and  Celluloid  are 
also  used. 

Buttons  of  vegetable  ivory  may  be  dyed  with  almost  any  of  the  sub- 
stantive or  basic  colors  dissolved  in  water,  the  buttons  being  steeped  in 
the  boiling  solutions  for  several  hours,  the  basic  colors  probably  giving 
the  best  penetration  while  the  substantive  colors  have  the  best  fastness  to 
rubbing.  The  color  at  best,  however,  penetrates  only  a  slight  distance 
below  the  surface.  The  mordant  dyes  and  the  natural  dyewoods  (or 
their  extracts)  are  also  largely  used  for  the  dyeing  of  vegetable  ivory  but- 
tons. In  this  case  it  is  necessir  y  to  fix  the  dye  by  treating  with  a  boiling 
solution  of  a  mordanting  salt  such  as  chrome  or  bluestone  or  copperas. 
The  matching  of  colors  on  vegetable  ivory  is  quite  difficult,  owing  to  the 
hard  working  qualities  of  the  material,  and  much  care  and  patient  skill 
must  be  exercised  in  order  to  obtain  the  desired  results. 

Dyeing  on  vegetable  ivory  buttons  is  frequently  done  in  a  style  to 
produce  pattern  effects  and  mottled  colors  where  several  different  tones  of 
color  are  desired.  These  effects  are  produced  by  using  cut  zinc  stencils 
to  cover  the  buttons  contained  in  trays  and  applying  the  dyestuff  by  means 
of  an  air-brush  or  sprayer.  The  dye  solution  is  made  up  with  some 
China  clay  for  purposes  of  thickening,  is  sprayed  on  hot  in  pattern  effects, 
using  the  dyes  for  the  lighter  shades  first  and  afterwards  the  heavy  colors. 
The  buttons  are  then  dried  and  the  paste  removed  from  the  surface  by 
drumming  with  damp  sawdust.  The  mordant  dyes  are  largely  used  for 
this  purpose,  so  the  colors  must  afterward  be  fixed  by  boiling  with  a  mor- 
dant, chro  ne  being  the  chief  salt  employed  for  this  purpose. 


646 


APPLICATION  OF  DYES  TO  VARIOUS  MATERIALS 


The  substaiitivo  dyos  aro  applied  to  vep;ptablo  ivory  buttons  by  dyeing 
for  one  hour  in  a  boiling  bath  containing  1  oz.  soda  ash  and  1  lb.  of  glauber- 
salt  per  10  gallons  of  liquor.  Then  the  goods  are  allowed  to  cool  down  in 
the  bath  and  finalh'  rinsed  well.  The  basic  colors  are  dyed  in  a  boiling 
bath  coi.taining  3  to  8  ozs.  of  acetic  acid  per  10  gallons  of  liquor.  WTien 
dyeing  heavy  shades  with  the  basic  colors  it  will  be  necessarv^  to  first  mor- 
dant the  buttons  with  tannic  acid  and  tartar  emetic  in  the  same  manner 
as  that  emploj'ed  for  the  mordanting  of  cotton. 

After  dyeing  and  rinsing  the  buttons  are  usually  dried  slowly  in  the  air, 
as  rapid  dyeing  in  hot  air  is  to  be  avoided  or  the  buttons  will  warp  and 
crack.     Or  the  wet  buttons  may  be  dried  b}-  drumming  in  sawdust,  which 


Fig.  291.— Atherton  Cloth  Trimmer.     (Curtis  &  Marble.) 


is  gradually  warmed.     After  drying  the  materials  are  polished  by  drum- 
ming with  fine  abrasives  such  as  powdered  button  waste,  emery,  etc. 

Horn  buttons  are  dyed  best  with  the  ]:»asic  colors,  using  a  bath  at  120°  to 
140°  F.  containing  a  small  amount  of  acetic  acid.  These  colors  exhaust 
well  at  the  low  temperature  and  the  material  is  not  affected.  Acid  dyes 
maj^  be  also  used,  but  these  require  the  dyeing  to  be  done  in  a  boiling  bath, 
which  usually  causes  the  buttons  to  become  softened  and  misshaped,  which 
is  a  great  disadvantage.  For  solid  shades  of  brown  and  various  mode 
colors  the  so-called  fur  dyes  may  be  used  to  advantage.  For  tliis  purpose 
the  buttons  must  be  mordanted  with  bluestone,  copperas,  or  chrome  by 
soaking  the  goods  in  a  solution  of  4  to  6  ozs.  of  the  mordanting  salt  in  10 
gallons  of  water.  Start  the  process  hot  and  allow  to  cool  down  in  the 
liquor  for  eight  to  ten  hours  (overnight).  Then  rinse  well  in  cold  water 
and  dye  in  a  solution  of  1  to  6  ozs.  of  the  dye  per  10  gallons,  starting  at 


DYEING   OP^   BUTTON    MATERIALS  647 

the  boil  and  allowing  to  cool  down  in  the  liquor.  Then  add  hydrogen  per- 
oxide (12  vol.)  to  the  extent  of  about  twelve  times  the  weight  of  dyestuff 
used,  and  then  leave  in  the  solution  until  the  shade  is  completely  developed, 
which  will  usually  require  about  six  hours.  In  the  dyeing  of  all  button 
material  the  goods  must  be  frequently  stirred  up  during  the  process. 
After  dyeing  wash  well  in  water  and  then  in  a  weak  soap  solution. 

Ivory  buttons  may  be  dyed  in  practically  the  same  manner  as  those  of 
horn.  This  also  apphes  to  the  dyeing  of  ivory  bilUard  balls  or  other  objects 
of  ivory. 

Mother-of-pearl  buttons  are  cut  from  shells  of  sea  mollusks,  and  it  is 
frequently  required  to  dye  them.  In  this  case  the  basic  dyes  are  mostly 
employed,  and  the  dyeing  is  done  either  in  an  alcoholic  solution  or  in  a 
water  solution  to  which  an  equal  volume  of  ale  ohol  is  added,  as  the  alcoholic 
liquor  penetrates  the  mother-of-pearl  material  and  stains  it  better  than 
water  alone.  Before  dyeing  the  material  is  prepared  by  steeping  in  a 
solution  of  potassium  carbonate  at  120°  F.  Then  wash  well  and  dry. 
The  goods  are  then  dyed  by  steeping  in  the  color  solution  for  several  hours 
or  until  the  desired  shade  is  obtained.  After  dyeing  rinse  well  in  cold 
water  and  dry  slowly  to  prevent  cracking.  Blacks  and  dark  browns  are 
frequently  produced  by  staining  the  buttons  with  a  solution  of  silver  nitrate 
and  allowing  to  oxidize. 

Gallalith  buttons  are  made  from  an  artificial  product  prepared  by 
treating  casein  with  formaldehyde.  The  substantive  and  acid  dyes  are 
chiefly  employed  for  the  coloring  of  this  material. 

Bakelite  (also  Condensite  and  Redmanol)  is  a  synthetic  plastic  obtained 
by  the  condensation  of  certain  phenols  with  formaldehyde.  It  is  usually 
of  a  yellowish  brown  color,  but  may  be  dyed  with  rather  good  effect  by 
using  basic  colors  in  the  same  manner  as  in  the  dyeing  of  buttons  of  vege- 
table ivory. 


CHAPTER   XXVIII 

APPLICATION     OF    DYESTUFFS     IN     THE    PREPARATION     OF 

LAKES,    INKS,    ETC. 

1.  Preparation  of  Color-lakes. — Lakes  are  insoluble  compounds  pro- 
duced with  dyestuffs  and  suitable  metallic  salts  or  bases.  They  are  used 
extensively  in  the  preparation  of  printing  inks,  hthographic  inks,  paints, 
and  in  the  printing  of  wall-paper  and  such  materials.  In  the  prepara- 
tion of  lakes  there  are  three  factors  to  be  considered:  (a)  the  mineral 
bases  or  carriers,  on  which  the  colors  are  precipitated,  the  most  mipor- 
tant  of  which  are  aluminium  hydrate  paste,  barytes,  white  fixing 
cla}',  China  clay,  and  green  earth,  it  being  essential  that  these  sub- 
stances are  of  a  very  finely  divided  impalpable  nature,  so  that  when 
suitably  mixed  with  water  they  furnish  a  smooth,  non-gritty  paste  of  a 
colloidal  character;*  (6)  the  precipitating  agents;  the  chief  ones  being 
barium  chloride,  lead  acetate,  tannic  acid  and  rosin  soap;  (c)  the  dj^estuffs; 
which  may  consist  of  the  acid,  basic,  phthalein  or  alizarine  dyes,  and  such 
dyes  prepared  in  situ  as  Paranitraniline  Red.f 

*  There  are  a  large  number  of  carriers  used  in  the  making  of  lakes,  including  alumina, 
artificial  barytes,  natural  barytes,  lead  sulphate,  zinc  white,  lithopone,  gypsum,  whiting, 
China  clay,  precipitated  chalk,  starch,  barium  carbonate,  magnesium  carbonate,  cal- 
cium phosphate,  natural  clays,  ochre,  umber,  green  earth,  rod  lead,  and  others.  The 
selection  of  the  carrier  depends  greatly  upon  the  use  to  which  the  lake  is  to  be  put. 
Lakes  intended  for  ordinary  painting  to  be  mixed  with  varnish,  oil,  or  spirit,  and  to  have 
good  covering  power,  should  have  carriers  like  lead  sulphate,  zinc  white,  lithopone, 
barytes,  or  red  lead.  In  the  making  of  colors  for  spirit  varnishes  artificial  barytes  will 
answer.  Lakes  intended  for  printing  wall-paper  are  usually  of  a  cheap  g  ade  and  are 
made  with  alumina,  artificial  or  natural  barytes  whiting,  clay,  starch,  and  the  white 
and  colored  clays.  Lakes  for  printing  fancy  papers  must  be  of  a  better  grade  and  have 
good  covering  power  and  give  a  uniform  coating,  and  the  carrier  used  may  be  alumina, 
artificial  barytes,  China  clay,  precipitated  chalk,  magnesium  carbonate,  and  some- 
times whiting.  Printing  inks,  lithographic  inks,  and  artists'  colors  require  lakes  of  the 
finest  character;  if  desired  as  transparent  pigments  these  are  made  with  alumina, 
either  alone  or  mi.xed  with  more  or  less  artificial  barytes;  if  desired  to  be  opaque  the 
carrier  used  may  be  lead  .sulphate,  zinc  white,  or  lithopone.  Lakes  known  as  lime 
colors  are  made  with  green  earth,  white  or  colored  clays,  barytes,  or  gypsum,  the  two 
latter  alw  lys  forming  the  jjriiicipal  part. 

t  The  following  classification  of  dyestufTs  for  lake-making  purposes  is  given  by  Zerr 

648 


PREPARATION   OF  COLOR-LAKES  649 

Lakes  from  the  acid  dyes,  as  a  rule,  are  prepared  by  precipitating  the 
dyestuff  solution  in  conjunction  with  aluminium  hydrate  either  prepared 
previously  as  a  paste  or  precipitated  during  the  making  of  the  lake  by  the 
interaction  of  aluminium  sulphate  and  soda  ash.  The  precipitated  dye  is 
carried  down  in  intimate  combination  with  the  alumina  forming  an  insol- 
uble lake  compound.  The  basic  dyes  are  usually  precipitated  on  China 
clay  or  barytes  by  the  addition  of  tannic  acid  or  rosin  soap ;  or  some  of  the 
basic  dyes  may  be  fixed  directly  (without  the  use  of  a  precipitating  agent) 
on  green  earth  (especially  used  for  the  basic  greens)  or  on  white  fixing  clay. 
The  alizarine  dyes  are  precipitated  with  alum,  soda  ash,  Turkey -red  oil 
and  calcium  acetate.  Of  rather  recent  years  there  is  a  class  of  insoluble 
azo  dyes  which  is  largely  used  in  the  preparation  of  lakes.  There  are 
quite  a  number  of  these  dyes  at  present  known,  some  of  the  more  impor- 
tant being  Helio  Fast  Red  G,  Lithol  Red,  Autol  Red,  Pigment  Orange,  etc. 
These  colors  are  prepared  in  the  form  of  pastes  and  the  lakes  are  made 
by  simply  mixing  the  dyestuff  with  suitable  carriers  by  mechanical  means. 
These  colors  are  largely  used  in  the  making  of  lithographic  inks,  paints,  and 
some  artists'  colors. 

In  the  preparation  of  lake  colors  the  various  reagents  are  usually 
employed  in  solutions  of  the  following  strengths: 

Aluminium  sulphate 1  :  20 

Soda  ash 1  :  20 

Barium  chloride 1  ;  20 

Acetate  of  lead 1  :  20 

Dyestuffs 1  :  50  or  1  :  100 

Aluminium  hydrate  paste  for  use  as  a  carrier  in  the  preparation  of 
lakes  may  be  prepared  as  follows:* 

and  Riibenkamp  {Treatise  on  Color  Manufacture) ;  the  classification  being  based  on  the 
methods  of  precipitation: 

(1)  Dyes  precipitated  by  the  aid  of  barium  chloride  (really  barytes,  as  the  barium 
salt  is  precipitated  as  sulphate) — all  the  acid  dyes. 

(2)  Dyes  precipitated  by  the  aid  of  lead  salts — principally  the  resorcine  or  eosin 
colors. 

(3)  Dyes  precipitated  by  tannin  or  tannin  and  tartar  emetic — all  the  basic  colors. 

(4)  Dyes  precipitated  by  alummium  hydrate — the  rosaniline  and  alizarine  colors 
only. 

(5)  Dyes  produced  directly  by  precipitation — the  insoluble  azo  or  ice  colors. 

(6)  Dyes  absorbed  directly  by  clays — the  basic  dyes  alone. 

This  classification,  however,  must  not  be  taken  too  rigidly,  as  dyes  of  one  group 
are  often  precipitated  by  the  medium  for  another  group.  For  example,  some  azo  dyes 
may  be  precipitated  by  lead  salts,  and  some  of  the  basic  dyes  form  suitable  lakes  under 
certain  conditions  with  barium  chloride  (Magenta,  Rhodamine,  Methyl  Violet,  etc.). 

*  Aluminium  hydrate  is  probably  the  most  important  carrier  used  in  the  making  of 
lakes  and  is  always  present  in  the  best  colors.  It  may  either  be  used  as  such  (and  for 
this  purpose  prepared  in  the  above  manner)  or  it  may  be  produced  at  the  sametime  that 


650  DYESTUFFS   IN   PREPARATION   OF  LAKES,   INKS,   ETC. 

3  lbs.  of  aluminium  sulphate  dissolved  in 
3  gallons  of  water,  and  add 
I5  lbs.  of  soda  ash  dissolved  in 
1|  gallons  of  water. 

Both  solutions  should  be  heated  to  160°  F.,  and  the  soda  ash  solution 
should  be  added  to  that  of  the  aluminium  sulphate  with  constant  stirring. 
Allow  to  settle,  wash,  filter  and  press  between  cloths  to  a  weight  of  7  lbs., 
which  will  furnish  a  10  per  cent  paste  of  aluminium  hydrate. 

The  following  methods  for  the  precipitation  of  lakes  have  been  recom- 
mended by  the  various  color  makers: 

(1)  Suitable  for  the  preparation  of  lakes  for  colored  papers  and  wall- 
papers:* 

60  lbs.  aluminium  sulphate  (1  :  20),  arc  mixed  with 
20  lbs.  soda  ash  (1  :  20),  then  add 
100  lbs.  barytes,  then  add 
15  to  30  lbs.  dyestuff  (1  :  50),  and  then  precipitate  at  85°  F. 
75  to  90  lbs.  barium  chloride  (1  :  20). 

This  method  is  employed  with  the  various  acid  dyes. 

(2)  Suitable  for  use  with  certain  acid  dyes,  such  as  Acid  Green,  Naph- 
thol  Green  B,  Cyanole,  Fast  Acid  Yellow  and  China  Yellow  B,  as  a  clearer 
waste  water  results  than  with  the  preceding  method: 

24  lbs.  aluminium  sulphate  (1  :  20)  are  mixed  with 

12  lbs.  soda  ash  (1  :  20),  then  add 
100  lbs.  barytes,  then  add 
10  to  25  lbs.  dyestuff  (1  :  50),  and  precipitate  at  85°  F.  with 

105  lbs.  barium  chloride,  and  then  i)recipitate  the  whole  again  with 

30  lbs.  aluminium  sulphate  (1  :  20)  hot  and 

10  lbs.  soda  ash  (1  :  20). 

the  lake  is  precipitated.  It  is  only  for  the  highest  grade  of  lakes  (for  printing  and 
lithographic  inks  and  artists'  colors)  that  aluminium  hydrate  is  used  alone;  for  other 
lakes  it  is  always  mixed  with  more  or  less  barytes,  the  more  barytes  the  lower  the  grade 
of  the  lake.  The  artificial  barytes  is  customarily  prepared  at  the  time  the  lake  is  pre- 
cipitated by  the  interaction  of  sodium  sulphate  and  barium  chloride,  as  this  gives  better 
results  than  if  the  ready-made  barytes  was  added  to  the  mixture.  In  making  aluminiinn 
hydrate  care  must  be  had  not  to  precipitate  it  with  caustic  alkali,  as  then  a  gelatinous 
and  slimy  mass  is  obtained  which  dries  to  a  hard  and  horny  material;  it  is  also  soluble 
in  excess  of  the  precipitating  agent,  therefore  is  unsuitable  for  the  making  of  lakes.  It 
is  on  this  account  that  the  precipitation  of  the  aluminium  hydrate  is  made  with  soda  ash, 
as  it  is  then  insoluble  in  excess  of  the  reagent,  is  less  gelatinous,  and  when  prepared  from 
dilute  solutions  and  at  a  higher  temperature  is  opacjue,  white,  and  when  dry  is  soft  and 
easily  powdered. 

*  The  best  types  of  wall-paper  lakes  should  not  contain  a  predominating  amount  of 
barytes,  especially  if  the  lake  is  sold  in  the  paste  form,  for  such  lakes  settle  down  quickly 
owing  to  the  high  gravity  of  the  barytes,  and  this  causes  trouble  in  the  printing  machines. 
Also  lakes  containing  barytes  are  not  suited  for  coloring  fancy  papers,  as  the  lake  is 
stiff  and  has  low  covering  power,  and  the  coating  becomes  hard  and  rough. 


PREPARATION   OF  COLOR   LAKES  651 

(3)  Suitable  for  the  precipitation  of  certain  of  the  substantive  dyes, 
such  as  Benzo  Sky  Blue,  Diamine  Blue  RW,  and  some  of  the  substantive 
brown  dyes;*  also  suitable  for  the  preparation  of  lakes  for  use  on  colored 
paper  and  cheap  lithographic  inks,  using  the  acid  dyes: 

75  lbs.  aluminium  sulphate  (1  :  20)  are  mixed  with 
35  lbs.  soda  ash  (1  :  20),  then  add 
100  lbs.  barytes,  then  add 
10  to  25  lbs.  dyestuff,  and  precipitate  at  85°  F.  with 
90  lbs.  barium  cliloride  (1  :  20) 

(4)  Suitable  for  most  of  the  acid  dyes  and  somewhat  cheaper  than 
(1)  while  at  the  same  time  yielding  somewhat  brighter  lakes: 

100  lbs.  barytas  are  mixed  to  a  paste  with 
6  lbs.  soda  ash  (1  :  20),  then  add 
10  lbs.  dyestuff  (1  :  50   and 
20  lbs.  barium  chloride  (1  :  20)  and 
13  lbs.  aluminium  sulphate  (1  :  20) 

(5)  Suitable  for  lakes  used  in  the  finer  lithographic  inks,  using  the  acid 
dyes: 

150  lbs.  aluminium  hydrate  paste  (10  per  cent)  are  mixed  with 
10  lbs.  dj-estuff  (1  :  50)  and  precipitated  with 
10  to  15  lbs  barium  chloride  (1  :  20) 

(G)  Suitable  for  lakes  for  wall-papers,  using  certain  acid  dyes  such  as 
Acid  Green,  Naphthol  Green,  Cyanole  and  Lake  Blue: 

60  lbs.  aluminium  sulphate  (1  :  20)  are  mixed  with 
30  lbs.  soda  ash  (1  :  20)  and 
100  lbs.  barytes,  wash  three  times  and  then  add 
15  to  30  lbs.  dyestuff  (1  :  50)  and  precipitate  with 
12  to  25  gallons  lead  acetate  solution  (52°  Tw.) 

*  The  following  are  two  examples  of  the  preparation  of  lakes  from  the  substantive 
dyes  (Bayer) : 

For  a  pink  lake. 

5  parts  Geranine  G  dissolved  in 
500  parts  hot  water  with 

100  parts  aluminium  hydrate  paste,  and  precipitate  with 

6  parts  barium  chloride  dissolved  in 
60  parts  water 

For  a  yellow  lake 
5  parts  Chloramine  Yellow  INI  dissolved  in 
500  parts  water  and  add 

15  parts  aluminium  sulphate  dissolved  in 
150  parts  water,  and  add 

7  parts  soda  ash  dissolved  in 
70  parts  water,  and  add 

24  parts  barium  chloride  dissolved  in 
240  parts  water,  precipitating  cold. 


G52  DYESTUFFS  IN  PREPARATION  OF  LAKES,   INKS,  ETC. 

(7)  Suitable  for  making  lakes  from  the  Eosin  dyes:* 

50  lbs.  aluminium  sulphate  (1  :  20)  are  mixed  with 
25  lbs.  soda  ash  (1  :  20)  and 

80  lbs.  barium  chloride  (1  :  20),  wash  three  times  and  add 
100  lbs.  barytes  and 

24  lbs.  dyestuff  (1  :  50),  and  precipitate  with  a  cold  solution  of 
30  lbs.  lead  acetate  or  lead  nitrate  (1  :  20) 

(8)  Another  method  for  making  the  Eosin  lead  lake  is  as  follows: 

100  parts  aluminium  hydrate  paste  arc  mixed  with 

15  parts  Eosin  dissolved  in 
1500  parts  water,  then  precipitate  cold  with 

12  parts  sugar  of  lead  dissolved  in 
120  parts  water. 

(9)  Suitable  for  use  with  most  of  the  basic  dj'es: 

100  lbs.  barytes  and 

50  lbs.  China  clay  are  mixed  to  a  good  paste,  then  add 
5  lbs.  dyestuff  (1  :  100)  and  precipitate  with  a  warm  solution  of 
7.5  lbs.  tannic  acid  dissolved  with 
7.5  lbs.  sodium  acetate  in  30  gallons  water. 

Better  precipitation  may  be  obtaned  by  the  addition  of  3  to  4  lbs.  tartar 
emetic  or  antimony  salt  (1  :  20)  after  the  tannic  acid,and  it  will  be  unnec- 
essary then  to  add  the  sodium  acetate. 

(10)  The  following  is  another  method  for  making  lakes  from  basic  dyes 
by  precipitation  with  tannic  acid  f  (Bayer): 

150  parts  aluminiimi  hj'drate  paste  in  water  mixed  with 
10  parts  basic  dyestuff,  dissolved  in 
1000  parts  water,  and  add 

10  parts  tannic  acid  dissolved  in 
100  parts  water,  then  add 
5  parts  tartar  emetic  dissoh^ed  in  100  parts  water. 

*  Lakes  from  the  Eosin  colors  give  finer  shades  when  precipitated  cold  than  when  the 
solution  is  warm.  When  drying  the  temperature  should  be  kept  as  low  as  possible  and 
never  over  120°  F.,  otherwise  the  color  will  turn  brownish.  The  Eosin  lakes  are  very 
susceptible  to  acids  and  the  shades  may  be  made  yellower  or  bluer,  depending  on  the 
more  or  less  acid  reaction  of  the  carrier  employed.  A  cheap  imitation  of  Vermilion  may 
be  obtained  by  using  red  oxide  of  lead  as  the  carrier. 

fin  precipitating  lakes  from  basic  dyes  with  tannic  acid,  to  obtain  bright  shades  it  is 
very  necessary  that  all  of  the  ingredients  should  be  free  from  iron,  as  small  traces  of 
iron  will  cause  a  considerable  dulling  of  the  color.  When  the  lake  is  intended  for  use  for 
lithographic  inks  it  is  best  to  complete  the  precipitation  by  the  addition  of  tartar  emetic. 
Lakes  from  basic  dyes  may  be  saddened  or  darkened  by  adding  some  copperas  with  the 
tartar  emetic. 


LAKES   WITH   BASIC   DYES  653 

(11)  Suitable  for  use  with  the  basic  colors  and  giving  especially  brilhant 
lakes : 

180  lbs.  aluminium  sulphate  (1  :  20)  are  precipitated  with 
90  lbs.  soda  ash  (1  :  20)  and  stirred  up  with 
100  lbs.  barytes,  wash  3  times  and  add 
20  lbs.  dyestuflf  (1  :  100)  and  precipitate  with 
80-100  gallons  rosin  soap  and 
30  lbs.  white  vitriol. 

The  rosin  soap  is  prepared  by  boiling  together  100  parts  rosin,  26  parts 
soda  ash  and  500  parts  water. 

(12)  Good  lakes  from  the  rosaniline  basic  dyes  may  be  prepared  with: 

80  lbs.  aluminium  hydrate  paste  (10  per  cent) 
20  lbs.  blanc  fixe  and 
2  lbs.  dyestuff  (1  :  50). 

(13)  A  process  recommended  for  the  basic  dyes  in  general  is: 

20  grams  dj^estuff  (1  :  100)  stirred  with 
100-400  grams  kaolin  and  add 

200  CO.  tannic  acid  solution  (20  per  cent)  and 
200  cc.  aluminium  sulphate  solution  (20  per  cent). 

(14)  Suitable  for  use  with  green  basic  dj^es  to  make  a  cheap  and  fast 
green  lake: 

100  lbs.  green  earth  are  mixed  with  water  and  add 
2  lbs.  dyestuff  dissolved  in  40  gallons  water. 

These  lakes  are  fast  to  light  and  lime,  but  not  so  bright  in  tone  as  those 
produced  by  methods  (8)  and  (9).  By  substituting  white  fixing  clay  for 
the  green  earth  and  using  such  basic  dyes  as  Magenta,  Methyl  Violet, 
Methylene  Blue,  Auramine,  and  Chrj^soidine,  bright  cheap  lakes  of  ^ood 
fastness  to  lime  may  be  prepared. 

(15)  Lakes  produced  with  the  acid  dyes  or  Para  Red  may  l)e  bright- 
ened or  toned  by  topping  with  basic  colors.  The  freshly  precipitated 
lake  is  washed  and  mixed  with 

5  to  10  lbs.  basic  dye  (1  :  50)  and  precipitated  with 

6  to  15  lbs.  tannic  acid  dissolved  in  30  gallons  water  with 
6  to  15  lbs.  sodium  acetate. 

Another  process  of  shading  with  the  basic  dyes  is  to  add  the  basic  color 
immediately  after  the  acid  color  and  then  precipitate  both  simultaneously 
with  barium  chloride  after  the  methods  given  for  use  with  the  acid  dyes. 
The  preparation  of  the  lake  colors  necessitates  xevy  careful  operation, 
and  many  factors  play  an  important  part  in  the  successful  outcome  of  the 
process  in  order  to  have  the  different  lots  of  the  same  color  match  accurately 


654  DYESTUFFS   IN   PREPARATION   OF   LAKES,    INKS,   ETC. 

in  shade  and  to  maintain  the  proper  brightness.  The  purity  of  the  chem- 
icals used  is  very  important  and  all  of  them  should  be  carefully  examined 
and  maintained  constant  in  type.  The  degree  of  alkalinity  and  acidity, 
the  concentration  of  the  solution,  the  temperature,  the  sequence  and 
duration  of  the  mixing,  and  even  the  manner  of  stirring  also  play  a  consid- 
erable part  in  the  results  obtained. 

When  barium  chloride  is  employed  as  the  precipitating  agent  it  forms 
with  the  dyestuff  an  insoluble  barium  compound  which  dyes  the  carrier 
or  base.  In  the  reaction  common  salt  is  formed  in  considerable  amount 
and  remains  in  solution,  and  this  must  be  washed  out  of  the  precipitated 
lake  in  order  that  it  may  have  the  proper  purity. 

(16)  A  process  given  for  use  with  the  acid  dyes  is: 

20  grams  dyestuff  dissolved  in 

2  liters  water  and  stirred  with 
100  to  400  grams  kaolin  and  add 

200  cc.  barium  chloride  solution  (20  per  cent)  and 
200  cc.  aluminium  sulphate  solution  (20  per  cent). 

(17)  A  process  for  Alkali  Blue  and  Fast  Green  is  as  follows: 

20  grams  dyestuff  dissolved  in 

3  liters  water  and  stirred  with 
100  to  400  grams  kaolin  and  add 

12  grams  stannoi'.s  chloride  dissolved  in 
20  cc.  water. 

(18)  A  process  for  the  Eosin  dyes  is  the  following: 

20  grams  dyestuff  dissolved  in 
2  liters  water  and  stirred  with 
100  to  400  grams  kaolin  and  add 

200  cc.  lead  acetate  *  solution  (20  per  cent). 

(19)  A  process  which  may  be  used  for  the  substantive  dyes  is: 

20  grams  dyestuff  dissolved  in 
2  liters  water  and  stirred  with 
100  to  400  grams  kaolin  and  add 

200  cc.  barium  chloride  solution  (20  per  cent). 

When  the  lakes  are  to  be  used  for  lithographic  purposes  it  is  generally 
to  use  aluminium  hydrate  paste  as  the  carrier  instead  of  kaolin,  blanc  fixe, 
barytes,  etc. 

Alizarine  lake  colors  are  precipitated  with  alum,  soda,  Turkey-red  oil, 
and  very  often  in  conjunction  with  lime  salts  so  that  a  double  lake-color 

*  Nitrate  of  lead  may  also  be  used,  l)ut  it  must  be  remembered  that  the  acetate  of 
lead  gives  a  more  yellow  tone  to  the  lake  than  the  nitrate. 


LAKES   WITH   ALIZARINE   DYES 


655 


with  alumina  and  lime  is  formed  which  has  a  better  tone  than  that  pre- 
pared from  alum  alone.  The  alizarine  lake-colors  are  very  fast  to  light  and 
water,  and  consequently  are  largely  used  for  paints,  water  colors,  litho- 
graphic inks  and  other  purposes  where  a  fast  color  is  desirable.  Some  of 
the  aUzarine  dyes  may  be  precipitated  cold  with  barium  chloride,  but  most 
of  them  have  to  be  boiled  with  an  addition  of  alumina  and  Turkey-red  oil 
so  as  to  develop  the  color.  The  precipitated  lake  is  washed  well  in  hot 
water,  filtered,  pressed,  and  dried  at  a  moderate  temperature.  Some  of 
the  lakes  (especially  those  from  Ahzarine  Red)  are  brightened  by  boiling 
with  steam  under  pressure. 


Fig.  292.— Double  Woolen  Shear.     (Parks  &  Woolson). 


(20)  A  typical  method  for  the  preparation  of  an  alizarine  lake  is  as 
follows : 

(a)  Precipitate  243  cc.  aluminium  sulphate  solution  (1  :  10) 

with  125  cc.  soda  ash  solution  (1  :  10)  wash  three  times 
Precipitate    30  cc.  calcium  chloride  solution  (1  :  10) 
with    70  cc.  sodium  phosphate  solution  (1  :  10) 
wash  twice  and  add  3  cc.  acetic  acid  solution  (1  :  10). 
(6)  Stir  up  30  grams  alizarine  dye  paste  with 
5  grams  Turkey-red  oil  and 
5  cc.  calcium  chloride  solution  (1  :  10)  and 
2  liters  water. 


656  DYESTUFFS   IX    PREPARATION   OF   LAKES,   INKS,   ETC. 

Then  add  (a)  to  (6)  and  allow  to  remain  for  several  hours  and  then 
gradually  bring  to  the  boil  and  boil  for  several  hours  until  the  color  is 
compJetcly  developed. 

The  chemicals  employed  as  well  as  the  water  and  the  vessels  used  must 
be  as  free  from  iron  as  possible  in  order  to  produce  a  clear  bright  lake.  By 
using  chromium,  tin,  or  iron  salts  in  place  of  or  together  with  the  alum  salt, 
the  colors  of  the  lakes  may  be  correspondingly  altered.  By  using  per- 
chloride  of  .tin  with  Alizarine  Red,  for  example,  a  much  brighter  and  more 
fiery  color  may  be  obtained. 

(21)  Another  process  for  the  making  of  alizarine  lakes  gives  the  fol- 
lowing proportions  of  the  ingredients: 

75  lbs.  sodium  phosphate 
20  lbs.  soda  ash 
10  lbs.  Turkey-red  oil 
35  lbs.  alizarine  dye  paste 
5  lbs.  acetate  of  lime. 

Valuable  and  beautiful  lakes  may  also  be  prepared  from  the  insoluble 
azo  dyes,  such  as  Paranitraniline,  Nitrotoluidine  Orange,  and  many  others 
of  that  class.  The  Para  Red  lake  is  a  brilliant  red  lake  having  very  good 
fastness  to  light,  water  and  lime,  and  also  possessing  great  tinctorial  power. 

(22)  To  prepare  Para  Red  lake  proceed  as  follows  (Bayer) : 

Solution  A. 

200  grams  Paranitraniline  S  (or  100  gr.  of  Paranitraniline  base)  are  stirred  up  well  with 
150  cc.  hj'drochloric  acid  (32°  Tw.),  in  a  few  minutes  stir  in  2  hters  boiling  water. 
Boil  for  a  short  time  until  the  Paranitraniline  has  become  perfectly  dissolved;  then  pour 
this  solution  in  a  fine  stream  into 

4  liters  water  as  cold  as  possible  with  constant  stirring. 
The  temperature  of  the  liquor  thus  mixed  should  not  be  above  50°  F. 
Then  pour  in  quickly  in  a  heavy  stream  into 
55  grams  sodium  nitrite  dissolved  in 
500  cc.  cold  water. 

After  a  short  time  a  clear  diazo  solution  results.  Should  the  solution  be 
turbid  it  indicates  either  that  the  temperature  was  too  high,  or  that  the 
nitrite  solution  was  not  addsd  quickly  enough,  or  that  there  was  not 
sufficient  nitrite.  The  latter  fact  is  easily  ascertained  by  testing  the  solu- 
tion mth  a  piece  of  iodide-starch  paper,  which  should  turn  blue,  show- 
ing a  slight  excess  of  nitrite. 

Solution  B 

115  grams  beta-naphthol  are  stirred  up  with 
265  cc.  caustic  soda  solution  72°  Tw.,  and  dissolve  in 
501  cc.  boiling  water,  then  add 
60  grams  Turkey-red  oil  and 
125  grams  soda  ash. 


PARANITRANTLTNE   LAKES 


657 


Solution  C 

243  grams  aluminium  sulphate  dissolved  in 
2500  cc.  water. 

Pour  solutions  A  and  C  simultaneously  in  a  fine  stream  into  solution  B. 
AVash  the  precipitated  lake  several  times  with  water  and  filter  and  dry 
at  a  low  temperature. 

Instead  of  using  alumina  as  the  carrier  barytes  may  be  employed,  in 
which  case  the  latter  may  be  mixed  directly  with  the  beta-naphthol  solu- 
tion. By  substituting  up  to  8  per  cent  of  the  beta-naphthol  wdth  Naph- 
thol  R  (beta-naphthol-7-sulphonic  acid)  a  lake  possessing  a  much  bluer 
shade  may  be  obtained  and  having  equally  as  good  fastness. 

By  using  Nitrotoluidinc  in  place  of  Paranitraniline  a  brilliant  orange 
lake  is  obtained  having  about  the  same  fastness  as  Para  Red.  A  good 
l)lue  lake  may  be  prepared  from  clianisidine  antl  beta-naphthol,  and  a 
brown  lake  from  alpha-naphthylamine  and  beta-naphthol  or  from  ben- 
zidine base  and  beta-naphthol. 

The  basic  and  acid  dyes  may  also  be  employed  for  the  purpose  of 
brightening  or  dyeing  the  ordinary  mineral  colors.  There  are  several 
different  processes  for  this  purpose,  the  simplest  being  that  of  staining  the 
pigment  by  stirring  it  up  in  a  solution  of  the  dyestuff.  The  pigment  being 
in  a  very  fine  state  of  division  will  absorb  (or  perhaps  more  properly  speak- 
ing adsorb)  some  of  the  dyestuff  and  will  have  its  color  altered  thereby. 
It  is  probable  that  the  dyestuff  is  simply  held  on  the  surface  of  the  fine  par- 
ticles of  the  pigment.  The  colors  produced  in  this  way  are  not  true  lakes 
of  the  dyestuffs  and  have  no  special  fastness,  especially  to  water.  x\lmost 
any  of  the  usual  acid  or  basic  dyes  may  be  employed  for  this  purpose. 

The  following  is  a  list  of  dyestuffs  that  are  particularly  well  adapted 
to  the  making  of  lakes: 


Acid  Alizarine  Blue  BB 

Acid  Blue  B,  R,  G 

Acid  Green  L 

Acid  Magenta  G 

Acid  Violets 

Alkali  Blues 

Alizarine  Orange  N 

Alizarine  Red 

Alpha-naphthylamine  salt 

Amaranth  Red 

Astacine  Red 

Auramine 

Autol  Orange 

Autol  Red 

Azarine 

Azo  Yellow  O 

Beta-naphthol 


Beta-naphthol  R 
Beta-naphthylamine  base 
Bismarck  Brown 
Bordeaux  G 
Brilliant  Black  B 
Brilliant  Carmine  L 
Brilliant  Croceine  3B 
Brilliant  Croceine  M 
Brilliant  Green 
Brilliant  Orange  G,  R 
Brilliant  Red  G,  R 
Brilliant  Rhoduline  Red  B 
Brilliant  Scarlet  G,  R 
Brilliant  Sky  Blue 
Brilliant  Violet  5B0 
Bromofluoresceine 
Capri  Blue  GON 


Chloranisidine  P 

Cotton  Scarlet 

Croceine 

Croceine  Scarlet  lOB 

Crystal  Scarlet  6R 

Crystal  Violet 

Curcumeine 

Eosin  O,  C,  B,  2G,  A,  S 

Eosin  Acid  L 

Erythrosine 

Excelsior  Scarlet  for  Lakes 

Formyl  Violet  S4B 

Gold  Orange 

Green  PL 

Guinea  Green  G,  B 

Guinea  Violet  4B 

Hclio  Azurine  PI,  BL 


658 


DYESTUFFS   IN   PREPARATION   OF   LAKES,   INKS,   ETC. 


Helio  Fast  Blue  BL,  SL 

Helio  Fast  Red  G 

Helio  Orange  RM 

Helio  Purpurine  B 

Lake  Blue,  I,  CB,  RT 

Lake  Bordeaux  B 

Lake  Green  BW 

Lake  Orange  ON 

Lake  Reds 

Lake  Scarlets 

Lake  \'iolct 

Lithol  Red  R,  2G 

Malachite  Green 

Manchester  Brown  2E 

Methylene  Blue  2B,  II 

Methyl  Green  SF 

Methyl  Violet  MB,  2B,  oB 

Milling  Yellow  O 

Mordant  Yellow  R,  G 

Naphthol  Yellow  S 

Naphthoi  Green  B 

Neptune  Green 

New  Magenta 

New  Methylene  Blue  F,  2G 


New  Red  L 
New  Solid  Green  2B 
New  Victoria  Blue 
Nile  Blue  2B,  R 
Nitrosamine  Red 
Nitrotoluidine 
Opal  Blue 

Orange  II,  ENL,  A,  2R,  2L 
Palatine  Lake  Scarlet  G 
Paper  Yellow  2G,  A,  3G 
Paranitraniline 
Patent  Blue  L 
Permanent  Red  6B 
Phosi)hinc  3R,  2G 
Phloxine  BA,  2BN 
Pigment  Bordeaux  R,  N 
Pigment  Chlorine  2G 
Pigment  Chrome  Yellow  L 
Pigment  Fast  Yellow  R,  G 
Pigment  Orange  R 
Pigment  Purple  A 
Pigment  Red  B,  G 
Pigment  Scarlet  3B 
Pluto  Orange  G 


Pyramine  Yellow  G  for  Lakes 

Pure  Blue  O 

(Juinoline  Yellow 

Rhodamine  B,  S,  G,  6G 

Rhoduline  Red  G 

Rose  Bengale  NT 

Rubine  N,  W 

Safranine  T,  MN,  BS,  2RA 

Scarlet    GRL,    4BG,    BO 

GVL,  GL,  RL,  4R 
Sky  Blue 
Solid  Green  FII 
Thioflavine  T 
Turquoise  Blue  G,  GL 
Vesuvine  BL,  4BG 
Victoria  Blue  R,  B,  4R 
Victoria  Yellow 
Victoria  Pure  Blue  B 
Water  Blue  R,  3R 
Wool  Blue  N 
Xylene  Blue  AS 
Xylidine  Scarlet 


The  following  dyes  produce  lakes  which  have  great  fastness  to  light : 


Alizarine  Orange  N 
Alizarine    Red    2A. 

PS,  V 
Astacine  Red 
Citronine  G,  A 
Fast  Navy  Blue  R 
Fast  Orange  O 


Helio  Fast  Blue  BL,  SL 
RX,     Helio  Fast  Red  G 
Lake  Bordeaux  B 
Lithol  Red  R,  2G 
Naphthol  R 
Naphthol  Yellow  S 
Naphthol  Green  B 


Permanent  Red  6B 
Pigment  Chrome  Yellow  L 
Pigment  Orange  R 
Pigment  Red  B 
Pigment  Scarlet  3B 


2.  Preparation  of  Spirit  Lakes. — These  lakes  are  soluble  in  alcohol  (or 
amyl  alcohol)  and  the  solution  is  used  by  brushing  on  the  surfaces  of  metals, 
wood,  glass,  bronze,  celluloid,  or  other  suitable  material  and  then  dried 
at  a  moderate  temperature.  These  lakes  are  prepared  mostly  from  the 
basic  colors  and  the  dyes  used  must  be  readily  soluble  in  alcohol  (or  methyl 
alcohol  or  amyl  alcohol)*.  From  5  to  30  grams  of  the  dyestuff  (depending 
on  the  depth  of  shade  desired)  are  dissolved  in  1  liter  of  alcohol,  the  solution 
filtered  if  necessary  to  obtain  a  clear  liquor,  and  then  mixed  with  1  liter  of 
what  is  known  as  capsule  lake,  which  is  prepared  by  dissolving  625  grams 
of  Gum  Sandarac  and  175  grams  of  Venice  Turpentine  in  1  liter  of  alcohol 
at  a  modera+ely  warm  temperature.     The  lake  is  emploj^'cd  in  the  form  of 

*  The  introduction  of  a  sulphonic  acid  into  a  dyestuff  usually  makes  the  dye  insoluble 
in  methyl  alcohol;  though  there  are  certain  exceptions  to  this  rule,  such  as  the  sulphon- 
ated  rosaniline  blues  (Soluble  Blue  and  Water  Blue). 


DYEING   OF  SOAP 


650 


its  solution  obtained  in  this  manner.     Other  varieties  of  spirit  varnisli 
may  be  used  for  this  purpose  in  the  same  manner. 
The  following  dyes  are  suita})le  for  this  purpose: 


Auramine 

Bismarck  Brown 

Brilliant  Croceine  R 

Brilliant  Green 

Cerasine  Dyes 

China  Green 

Chrysoidine 

Eosin 

Induline  (spirit  sol.) 

Irisamtne 


Janus  Dyes 
Leather  Yellow 
Magenta 
Malachite  Green 
Metanil  Yellow 
Methyl  Violet  B,  R 
Methylene  Blue 
Methylene  Violet 
Naphthylamine  Yellow 
Nigrosine  (spirit  sol.) 


Phosphine 
Rhodamine 
Rhoduline  Violet 
Rosazeine 
Safranine 
Tannin  Heliotrope 
Tannin  Orange  R 
Thioflavine  T 
Victoria  Blue  B 
Victoria  Yellow 


3.  The  Dyeing  of  Soap.— Soap  may  be  dyed  according  to  two  different 
methods:    (1)  The  color  solution  is  added  directly  to  the  refining  pan  con- 


FiG.  293. — Two-cylinder  Double-acting  Brushing  Machine  with  Steaming  Apparatus. 

(Curtis  &  Marble.) 


taining  the  melted  soap,  or  (2)  the  color  solution  may  be  added  to  the  dry 
soap  shavings  and  the  mixture  worked  in  a  suitable  mixing  or  kneading 
machine  until  the  color  is  thoroughly  incorporated  with  the  soap.  The 
d3'estuffs  employed  for  the  first  method  are  somewhat  limited  in  number 
as  the  color  must  be  capable  of  mthstanding  the  action  of  the  boiling 
alkaline  soap  solution.  Sometimes  the  dye  may  be  changed  on  boiling 
but  comes  back  to  the  proper  color  again  on  cooling.  In  applying  the  color 
the  dye  is  dissolved  in  as  small  an  amount  of  water  as  possible  with  the 
addition  if  necessary  of  some  alcohol  and  a  little  caustic  soda.  When 
hot  saponification  is  used  (curd  soap,  etc.)  the  solution  of  dyestuff  should 
not  be  added  until  after  the  saponification  is  complete,  but  when  cold 
saponification  is  employed  (cocoanut  oil  soap,  etc.)  the  dyestuff  solution 
may  be  added  during  the  process. 


660  DYESTUFFS   IX    PREPARATION   OF   LAKES,    INKS,    ETC. 

The  following  dyes  are  suitable  for  the  coloring  of  soap: 


Acid  Brov.ii  B,  G 
Acid  Congo  R 
Acid  Violet  HW 
Alkali  Fast  Green  B 
Azo  Yellow  O,  R 
Bismarck  Brown 
Brilliant  Croceine  3B 
Brilliant  Orange  G,  O,  R 
Chlorantine  Blue  B 
Chlorantine  Brown  B 
Chlorantine  Orange 
Chlorantine  Red 
Chlorantine  Rose 
Chlorantine  Yellow 
Coriphosphine 
Cotton  Blue 
Cotton  Red  C 
Cotton  Yellow 


Croceine  Orange  G,  R 

Direct  Green 

Eosin 

Erj'throsine 

Ethyl  Blue 

Fast  Acid  Violet  A2R 

Fast  Brown 

Fast  Green 

Fast  Light  Yellow  G 

Fast  Red  O 

Indian  Yellow  G,  R 

Induline  B 

Ketone  Blue 

Mandarine  G 

Metanil  Yellow 

New  Patent  Blue 

Night  Blue 

Orange  II 


Orange  IV 

Paper  lied  E 

Paper  Scarlet  G,  R,  B 

Patent  Blue  A,  V 

Quinoline  Yellow 

Rhodamine  B,  G 

Rosazeine 

Safranine 

Scarlet  (various  brands) 

Soap  Dj-es 

Soluble  Blue 

Tartrazine 

Transparent  Brown  O 

Transparent  Green  O 

Transparent  Violet 

Vesuvine  4BG 

Victoria  Yellow 

Wool  Blue  N 


4.  Dyestuffs  for  Inks. — In  former  times  black  inks  were  made  prin- 
cipally from  tannic  and  gallic  acids  and  iron  salts  or  soluble  Prussian  blue, 
but  at  the  present  time  with  the  very  extensive  use  of  fountain  pens  it  is 
necessary  to  have  a  completely  soluble  ink  which  will  not  settle  out  in  the 
least,  and  many  of  these  inks  are  now  prepared  with  suitable  coal-tar 
dj^estuffs,  either  alone  or  in  combination  with  tannin-iron  inks.  For  ordi- 
nary' writing  inks  dyes  that  are  fast  to  light  and  very  soluble  in  water  are 
selected  and  the  ink  consists  of  the  dyestuff  solution  in  water  to  which  is 
added  a  small  quantity  of  gum  arable  and  alcohol.  In  the  preparation 
of  copying  inks  some  hydroscopic  agent  must  be  added,  such  as  glycerin, 
glucose,  sugar,  dextrin,  etc.  Hectograph  inks  require  a  larger  quantity 
of  glycerin.  In  all  inks  a  small  quantity  of  carbohc  acid  or  salicylic  acid 
is  added  as  a  preservative.  Colored  inks  other  than  black  are  nearly 
always  made  at  the  present  time  from  dyestuffs. 

The  following  methods  recommended  by  different  dye  manufacturers 
will  illustrate  the  process  of  ink  making. 

(1)  ^Method  of  preparing  aniline  ink: 

5  to  2  lbs.  of  dyestuff  are  dissolved  with 
6    to  8  ozs.  gum  arable  in 

10  gallons  water,  and  add 
^  pint  alcohol  solution  salicylic  acid  (1  :  10). 


To  prepare  a  copying  ink  the  above  method  may  be  used  with  the  addi- 
tion of  4  to  5  lbs.  of  glycerin. 


INKS  FROM   DYESTUFFS  661 

(2)  Method  of  preparing  red  ink : 

1    oz.  Eosin  S  (yellow  shade)  dissolved  in 

5    pints  distilled  water,  and  stir  slowly  into  hot 

1    oz.  gum  arabic  dissolved  in 

2 5  gallons  distilled  water. 

(3)  A  violet  hectograph  ink  is  made  as  fohows: 

100  grams  Methyl  Violet  dissolved  in 

50  grams  acetic  acid  (9°  Tw.) 
100  grams  alcohol 
100  grams  distilled  water 

50  grams  glycerin. 

(4)  A  black  ink  not  affected  by  water  is  made  as  follows: 

A.  2\     lbs.  tannic  acid  dissolved  in 
1       gallon  water 

2 1     lbs.  copper  sulphate  dissolved  in 
1       gallon  water 
2 1     pints  acetic  acid 

y-*5  pint  hydrochloric  acid 
Make  up  to  10  gallons  with  water; 

B.  2\     lbs.  Naphthol  Black  L  115 

f  pint  alcoholic  solution  salicylic  acid  (1  :  10) 
Make  up  to  10  gallons  with  water. 

Then  mix  the  two  solutions  together. 

(5)  Tannin  ink  shaded  with  a  dyestuff:   (so-called  ahzarine  ink): 

23.4  parts  tannic  acid 

7.7  parts  gallic  acid 

7.2  parts  hydrochloric  acid 
10      parts  gum  arabic 
30      parts  copperas 
1  to  3  parts  dyestuff 

i  part  salicylic  acid  (or  1  part  carbolic  acid) 

937  parts  water. 

The  tannic  and  gallic  acids  are  dissolved  in  warm  water  and  the  gum  arabic 
in  cold  water,  mixing  the  two  solutions  when  cold,  then  add  the  hydro- 
chloric acid  and  the  copperas  dissolved  in  cold  water,  and  finally  the 
salicylic  acid.*  The  solution  is  then  allowed  to  settle  for  four  to  five  days, 
is  filtered,  and  then  the  dyestuff  (tV  to  i  per  cent)  in  solution  is  added  to 
the  filtered  liquid.  Soluble  Blue  is  mostly  used  for  this  purpose,  with 
slight  additions  of  such  dyes  as  Cyanole,  Acid  Green,  or  Naphthol  Black. 
*  Many  inks  at  the  present  time  are  supplied  in  powder  form,  the  ink  being  made  up 
simply  by  addition  of  cold  water.  Ink  powders  usually  consist  of  the  properly  propor- 
tioned mixture  of  tannin,  copperas,  and  dyestuff,  with  a  small  amount  of  salicylic  acid 
as  a  preservative. 


6G2 


DYESTUFFS   IX   PREPARATION   OF   LAKES,   INKS,   ETC. 


Patent  Blue.  Ketone  Blue,  Naphthalene  Green,  Xigrosine,  Night  Blue, 
New  Patent  Blue,  and  Dianil  Black  may  also  be  used.* 
(6)  Method  for  preparing  stamping  inksrf 

1  to  I5  lbs.  dyestuff  dissolved  in 
6    lbs.  glycerin  and 

3    pints  water  in  which  are  previously  dissolved 
2§  lbs.  gum  arabic. 

A  very  good  ink  may  be  prepared  by  the  use  of  a  special  dyestuff 
known  as  Hydra  Black,  as  this  possesses  great  fastness  to  Ught  and  excel- 
lent solubility.  The  solution  is  made  with  40  grams  per  liter  for  ordinary 
writing  inks  and  80  to  100  grams  per  liter  for  copying  inks. 

The  following  dyes  are  suitable  for  the  preparation  of  inks;  as  they 
resist  the  action  of  metallic  salts  and  acids  and  may  be  used  for  the  better 
quality  of  anihne  inks,  shading  tannin  inks,  and  the  so-called  alizarine  inks: 


Acid  Green 

Brilliant  Cochineal  2R 
Cotton  Blue 
Cyanole' extra 
Ketone  Blue  4BX 


Naphthalene  Green  V 
Naphthol  Black  L 
Xaphthol  Blue  Black 
New  Patent  Blue  B 
Nigrosine 


The  following  dyes  are  affected  by  metallic 
fore  are  only  suitable  for  producing  aniline  inks, 
graph  inks: 


Acid  Violet 
Amaranth  G,  B 
Auramine 
Bistnarek  Brown 
Brilliant  Green 
Carbon  Black 
China  Green 
Crystal  Violet 


Diamond  Fuchsine 

Eosin 

Eosin  Scarlet  B 

Er^'throsine 

Induline 

Jute  Black 

Magenta 

Malacliite  Green 


Patent  Blue  A,  V 
Pure  Soluble  Blue 
Tetra  Cyanole  V 
Water  Blue 

salts  and  acids  and  there- 
stamping  inks,  and  hecto- 

:\Iethyl  Violet 
Methylene  Blue 
Nerazine  G 
New  Magenta 
Orange  II 

Rhodamine  B,  G,  6G 
Rosazeine 


*  The  use  of  the  dyestuff  in  this  case  is  for  the  so-called  "  sighting  "  of  the  ink; 
that  is.  making  the  writing  clearlj'  visible  until  the  oxidation  of  the  iron  tannate  by  the 
atmosphere  leads  to  the  full  development  of  the  color  of  the  ink.  Nearly  all  of  the 
better  quality  inks  depend  for  their  final  color  on  the  development  of  iron  tannate. 
Soluble  Blue  is  especiallj^  suitable,  as  it  is  not  precipitated  on  long  standing  with  tannin, 
whereas  manj  other  dyes  are. 

t  Marking  inks  for  laundry  use  are  now  mostly  made  on  a  bases  of  Aniline  Black. 
The  following  formula  is  given  by  Whittaker : 


Sohdioti  A 

85  parts  copper  chloride 
106  parts  sodium  chlorate 

53  parts  ammonium  chloride 
600  parts  water 

Mix  1  part  A  with  4  parts  B  just  before  use. 
to  develop. 


Solulion  B 
30  parts  glycerin 
20  parts  gum 
40  parts  water 
60  parts  aniline  salts 
90  parts  water 
The  ink  takes  twelve  to  twenty-four  hours 


DYEING   TYPEWRITER   RIBBONS,   PERFUMES,   ETC  663 

5.  Dyestuffs  for  Typewriter  Ribbons. — The  inks  used  for  typewriter 
ribbons  are  made  from  basic  dyes  rubbed  down  to  a  fine  paste  with  vaseUne 
oil  and  this  is  used  for  impregnating  the  ribbons.  Glycerin  may  also 
be  used  in  place  of  mineral  oil,  using  5  lbs.  of  dyestuff  rubbed  up  with  25 
lbs.  of  glycerin  and  then  dissolving  by  heating  to  195°  F.     Should  any 


Fig.  294. — Velvet  and  Plush  Shear.     (I-'arks  &  Woolson.) 

dyestuff  separate  during  cooling  a  little  water  is  added  and  the  mixture 
heated  again.     The  following  dyes  are  mostly  used: 

Carbon  Black  Methyl  Violet  Safranine  G 

Jute  Black  Methylene  Blue  Scarlet  for  Cotton 

6.  Dyeing  of  Perfumes. — As  perfume  materials  are  dissolved  in  alcohol 
the  dyestuffs  employed  for  tinting  the  perfumes  must  be  soluble  in  alcohol. 
The  dyes  mostly  employed  are: 

Eosin  Metanil  Yellow  Induline  B 

Rhodamine  B,G,  6G  Quinoline  Yellow  Bismarck  Brown 

7.  Dyeing  of  Candles,  Oils,  and  Waxes. — In  dyeing  these  materials 
dyestuffs  must  be  employed  which  arc  soluble  in  oil.     There  are  many 


664  DYESTUFFS   IN   PREPARATION   OF   LAKES,   INKS,    ETC. 

special  d5^es  prepared  by  combining  the  bases  of  basic  dyes  with  a  fatty 
acid,  such  as  stearic  acid,  by  mehing  the  base  with  the  acid.  The  com- 
bination thus  obtained  is  soluble  in  oils  and  waxes.  These  special  dyes 
are  known  under  various  names,  such  as  Cerasine,  Ceres,  Fat  Dyes,  Sudan 
Dyes,  etc.  Many  of  the  basic  dyes  may  also  be  used  directly.  To  dye 
the  material  the  color  is  warmed  up  with  the  grease  or  wax  and  thoroughly 
mixed. 

The  following  dyes  are  suitable  for  this  purpose : 

Alizarine  Blue  SKY  (oil  sol.)  Ceres  Dyes  Indazine  (oil  sol.) 

Alizarine  Green,  C,  V  Diamond  Fuchsine  Nigrosine  Base 

Brilliant  Green  Diamond  Orange  Oil  Soluble  Dyes 

Brilliant  Scarlet  (oil  sol.)  Eosin  S  Rhodamine  B,  G,  6G 

Cerasine  Dyes  Fat  Dyes  Safranine 

8.  Use  of  Dyestuffs  for  Coloring  Food  Products. — Coloring  matters 
have  long  been  used  for  the  tinting  or  d^'eing  of  various  food  products 
In  former  times  many  natural  dyes  were  employed  for  this  purpose,  a  good 
example  being  the  coloring  of  butter  3^ellow  by  the  use  of  Annatto.  In 
preserving  fruits  and  vegetables,  it  often  happens  that  the  natural  colors 
with  which  we  are  familiar  in  the  fresh  material  are  lost  or  changed,  and 
in  order  to  give  the  preserved  product  a  more  natural  appearance,  recourse 
is  had  to  addition  of  suitable  coloring  matters.  With  the  advent  of  the 
CDal-tar  dyes,  it  was  not  long  before  many  of  them  were  used  in  the  coloring 
of  food  products,  confections,  liquors,  etc.  The  practice  became  so  wide- 
spread that  considerable  opposition  was  aroused  in  this  country  over  the 
use  of  "  poisonous  aniline  dyes  "  in  materials  used  for  food  purposes.  As 
a  result  the  U.  S.  Government  had  a  very  thorough  investigation  of  the 
matter  made  with  the  result  that  it  authorized  the  use  of  certain  coal-tar 
dyestuffs  for  the  coloring  of  such  products.  At  the  present  time  these 
dyes  comprise  the  following : 

Amaranth  Light  Greer.  SF,  yellowish  Sudan  I 

Butter  Yellow  Naphthol  Yellow  S  Tartrazine 

Erythrosine  Orange  I  Yellow  AB 

Indigo  Carmine  Ponceau  3R  Yellow  OB 

These  colors  have  been  selected  for  permitted  use  in  foods  and  beverages 
on  account  of  their  known  harmless  character,  and  furthermore  their 
methods  of  manufacture  are  such  that  pure  products,  free  from  any  poi- 
sonous ingredients,  can  be  obtained. 

All  of  the  colors  belong  to  the  class  of  acid  dyes  with  the  exception  of  the 
last  two,  which  are  fat  soluble  dyes. 

The  number  of  food  products  which  are  customarily  artificially  colored 
is  very  large,  including  butter  and  cheese,  Hquors,  wines,  distilled  liquors, 
egg  powders,  custard,  blanc-mange,  jelUes,  chocolates,  candies  and  con- 


DYES   USED   IN    FOODS,    INDICATORS   AND    MEDICINE 


GG5 


fections  of  all  sorts,  cakes,  lemonades  and  soft  drinks  of  various  kinds,  mus- 
tard, pickles,  ices,  preserved  and  canned  fruits  and  canned  vegetables. 
Dyes  used  for  coloring  food  products  must  be  very  soluble,  and  the  solu- 
tions must  not  show  turbidity  on  standing.  Besides  the  coal-tar  dyes 
specified  above,  there  are  also  a  number  of  preparations  from  various 
natural  dyes  used  in  coloring  foods  and  beverages. 

9.  Use  of  Dyestuffs  as  Indicators. — Some  of  the  dyestuflfs  may  be  used 
as  indicators  in  chemical  analysis  by  reason  of  their  sensitiveness  to 
alkalies  or  acids.  Congo  Red,  for  example,  is  very  sensitive  to  acids, 
turning  from  a  bright  red  color  to  a  dark  blue  in  the  presence  of  acid. 
Some  dyestuffs,  in  fact  that  have  no  value  for  purposes  of  dyeing,  are  very 
useful  as  indicators,  such  as  Methjd  Orange  or  Orange  III.  Other  dj'es 
useful  as  indicators  are  as  follows: 


Afid  Magenta 
Alizarine  Red 
Alizarine  Blue  S 
Alizarine  Green 
Alkali  Green 
Benzo  Purpurine  B 
Congo  Red 


Croceine 
Erythrosine 
Fast  Red 
Fluoresceine 
Indigo  Carmine 
Magdala  Red 


Malachite  Green 
Methyl  Green 
Methyl  Orange 
Methyl  Violet 
Phenolphthalein 
Tropaeoline 


10.  Use  of  Dyestuffs  in  Medicine. — Many  dyestufTs  have  been  used  in 
clinical  analysis  as  microscopic  stains,  and  specially  purified  products 
have  long  been  manufactured  for  this  purpose.  Also  some  dyes  or  dye- 
stuff  intermediates  have  been  used  as  drugs  on  account  of  their  specific 
physiological  effects,  as  for  example,  jMethylene  Blue  and  Phenolphthalein. 
Recenth"  it  has  been  shown  that  certain  dyes  possess  strong  antiseptic 
properties  and  may  be  used  to  excellent  advantage  in  the  treatment  of 
wounds  to  prevent  gangrene,  or  in  certain  diseases  where  strong  antiseptics 
are  needed,  as  when  dealing  with  the  invasion  of  streptococcus,  gonococcus, 
and  parasitic  bacilli.  An  acritline  dye  known  as  Flavine  is  particularly 
valuable,  as  are  also  Malachite  Green,  Brilliant  Green  and  Acid  Scarlet  R. 


CHAPTER    XXIX 

TESTING  OF  DYESTUFFS 

1.  To  Obtain  the  Money  Value  of  a  Dyestufif  Sample. — In  the 
testing  of  a  dj^estuff  sample  for  its  mone}'  value  it  is,  of  course,  necessary 
to  test  it  in  comparison  with  another  sample  of  the  same  (or  a  strict!}^ 
similar)  dj'estuff  of  a  known  or  established  money  value.  Take  tv.o 
samples  of  Wool  Blue  and  prepare  solutions  of  the  same  containing  2.5 
grams  per  liter,  labeling  them  "A"  and  "  B."  Prepare  two  dj'ebaths  con- 
taining the  same  amount  of  water,  acid,  and  glaubersalt,  and  add  10  cc.  of 
the  respective  dyestufif  solutions.  Then  dye  two  test  skeins  of  woolen 
yarn  identical  in  character  and  weight  in  these  baths,  maintaining  carefully 
the  same  conditions  as  to  temperature  and  time  of  dj'eing  in  both  cases. 
After  dyeing  in  the  usual  manner  for  forty-five  minutes,  remove  the  two 
skeins,  squeeze  the  excess  of  liquor  back  into  the  respective  dyebaths,  and 
then  dr}'  up  portions  of  the  two  skeins.  Now  compare  these  for  depth  of 
color  and  set  aside  the  hea^'ier  shade  for  comparison;  continue  dyeing  the 
weaker  shade,  adding  to  the  dyebath  sufficient  of  its  respective  color  to 
bring  the  shade  to  a  match  with  the  other  sample.  The  amounts  of  the 
two  dyestufif  solutions  used  to  produce  the  same  depth  of  shade  will  be 
inversely  proportional  to  the  values  of  the  respective  dj'es,  so  if  the  actual 
money  value  of  one  of  the  samples  is  known  it  is  a  simple  matter  to  calcu- 
late the  relative  value  of  the  second.  For  example,  suppose  that  on  the 
first  dyeing,  sample  "  A  "  proved  to  be  strongest  dyestufif;  on  continuing 
the  d^'eing  of  "  B,"  it  was  necessarj^  to  use  2.5  cc.  more  dye  solution  to 
match  "  A  ";  further,  suppose  that  sample  "  A  "  was  priced  at  42  cents 
per  pound.     TMiat  would  be  the  relative  money  value  of  "  B  "? 

Dye  solution  used  for  "  A,"     10     cc. 
Dye  solution  used  for  "  B,"     12.5  cc. 

Then         12.5  :  10  =  42  :  .r 

and  x=  — ,>,^^  =  33.6  cents  per  pound. 

This  method  of  testing  the  comparative  strength  or  value  of  dyestufifs 
may  be  carried  to  a  rather  high  degree  of  accuracy,  but  it  is  necessary  that 

666 


TESTING    VALUI<:   OF    DYKSTUFFS  66V 

the  comparative  dyetests  be  made  under  exactly  the  same  conditions  in 
every  respect,  and  also  that  the  eye  be  trained  to  match  the  depth  of  colors 
with  great  accuracy.  The  amounts  of  the  dye  solutions  should  be  accu- 
rately measured  by  means  of  a  graduated  pipette,  and  exactly  the  same 
amounts  of  sulphuric  acid  and  glaubersalt  should  also  be  taken  by  means  of 
definitely  measured  solutions;  and  further  the  total  volume  of  each  dyebath 
should  be  the  same.  To  insure  the  most  accurate  results,  it  is  best  to  carry 
out  a  second  dyeing  of  the  weaker  sample,  using  the  required  amount  of  its 
solution  added  to  the  bath  all  at  one  time.  This  is  especially  desirable  if  the 
second  sample  has  been  brought  to  a  match  by  a  number  of  successive  addi- 
tions of  the  color  solution.  For  instance,  in  the  sample  quoted  above, 
suppose  the  several  additions  of  the  color  solution  of  "  B  "  to  have  been  as 
follows : 

First,         10  cc.  Fourth,  0.5  cc. 

Second,       1  cc.  Fifth,     0.3  cc. 

Third,       0.5  cc.  Sixth,     0.2  cc. 

making  in  all  12.5  cc.  It  would  be  better  then  to  dye  another  skein,  using 
12.5  cc.  as  a  first  addition  to  the  dyebath.  It  will  frequently  be  found 
that  a  slightly  increased  amount  of  the  dye  solution  will  be  required  to 
bring  this  second  test  to  a  match.  This  is  accounted  for  by  the  fact  that 
the  prolonged  dyeing  necessitated  by  the  numerous  additions  to  the  bath 
will  cause  an  abnormal  absorption  of  dyestuff. 

If  properly  carried  out,  this  method  of  analysis  is  capable  of  giving 
results  accurate  to  within  at  least  5  per  cent,  provided  the  samples  being 
tested  are  the  same  kind  of  dyestuff.  If,  however,  the  dyes  are  not  quite 
of  the  same  tone  of  color,  some  difficulty  may  be  experienced  in  judging 
accurately  the  point  at  which  the  samples  are  matched  and  considerable 
skill  in  matching  will  be  required  to  arrive  at  their  proper  valuation. 
The  matching  in  this  case  may  be  usually  rendered  somewhat  easier  by 
observing  the  colors  through  red,  blue,  or  yellow  glasses,  which  have  the 
effect  of  cutting  out  certain  undesirable  tones.  Furthermore,  the  eye  is 
more  sensitive  to  differences  in  intensity  of  some  colors  than  in  others ;  for 
instance,  it  is  quite  difficult  to  detect  small  differences  in  the  depth  of 
yellow  colors,  whereas  in  blues  or  reds  small  differences  are  easily  detected. 
Violet  colors  and  reddish  tones  of  blue  are  also  rather  difficult  to  match 
accurately;  and  dull  and  broken  tones  of  any  color  are  harder  to  approxi- 
mate than  clear  and  bright  tones.  It  is  not  well  to  employ  too  heavy  shades 
for  comparison,  or  the  accuracy  of  the  method  will  be  much  impaired. 

As  sometimes  one  dyestufT  may  exhaust  better  in  the  first  bath  than 
another  corresponding  dye,  or  even  with  the  same  dyestuff  it  is  at  times 
possible  to  mix  with  it  some  chemical  to  cause  it  to  exhaust  better  than 
when  pure,  in  the  practical  testing  of  dyes  it  is  best  to  make  an  exhaust  test. 


668  TESTING   OF   DYESTUFFS 

This  is  done  b^^  diluting  thj  dyebath  used  for  the  first  dyeing  to  its  original 
volume,  and  without  the  further  addition  of  dyestuff  or  reagents,  to  dye  a 
second  test  skein.  The  intensity  of  the  dyeing  thus  obtained  will  measure 
the  degree  of  exhaustion  of  the  dyestuff  in  the  first  bath. 

It  is  not  well  to  employ  too  heavy  shades  for  comparison;  as  a  rule, 
from  I  to  1  per  cent  dyeings  will  be  found  quite  satisfactory  for  most  colors. 
In  the  case  of  black  dyes,  however,  where  it  is  necessary  to  obtain  a  com- 
parison of  the  tone  of  black  produced,  it  will,  of  course,  be  necessary  to 
use  more  than  1  per  cent  of  dyestuff. 

In  cases  where  the  test  skeins  must  be  mordanted  or  otherwise  treated 
before  or  after  the  dyeing,  care  must  be  taken  that  the  several  skeins 
employed  in  the  tests  receive  exactly  the  same  manner  and  degree  of  treat- 
ment. In  order  to  insure  the  proper  conditions  it  is  best  to  mordant  all 
the  test  skeins  used  simultaneously  and  together  in  the  same  bath;  and 
this  should  also  be  done  where  any  after-treatment  of  the  dyeing  is  required. 

Make  a  comparative  test  of  two  samples  of  a  substantive  cotton  color; 
two  samples  of  a  basic  color  for  cotton,  mordanting  with  tannin-antimony; 
two  samples  of  an  alizarine  color  for  wool  on  a  chrome  mordant;  and  two 
samples  of  an  anthracene  color  for  wool,  after-mordanting  with  chrome. 
In  all  these  cases  make  exhaust  tests  in  the  same  dyebath. 

2.  To  Determine  if  a  Dyestuff  is  Simple  or  Mixed. — A  large  number  of 
the  dyestuffs  on  the  market  are  not  sunple  or  single  coloring  matters,  but 
consist  of  two  or  more  dyestuffs  mixed  together.  This  mixing  of  colors  is 
practiced  for  the  purpose  of  altering  the  tone  of  the  dyestuff;  or  for  the 
forming  of  various  colors,  such  as  the  production  of  a  green  by  mixing  a 
blue  and  a  yellow  dye.  It  is  also  practiced  for  the  purpose  of  adulterating 
various  dyes  with  others  of  cheaper  quality. 

The  presence  of  mixtures  in  a  dyestuff,  however,  must  not  always  be 
taken  as  evidence  of  sophistication.  In  the  manufacture  of  dyestuffs  it 
often  happens  that  successive  lots  of  the  same  coloring  matter  do  not 
exhibit  precisely  the  same  tone,  but  it  is  very  desirable  to  the  dyer  tliLt 
the  dyestuff  as  sold  should  alwajs  be  of  exactly  the  same  tone.  The  man- 
ufacturer, therefore,  adopts  a  standard,  and  tones  the  various  lots  to 
match  this  standard  by  the  proper  addition  of  suitable  but  similar  dyes. 
Therefore  a  dyestuff  may  be  a  perfectly  true  article  and  yet  show  evidence 
of  mixed  colors.  The  amount  of  mixture,  however,  under  these  circum- 
stances is  very  small;  whereas  admixture  for  purposes  of  sophistication 
is  usually  rather  large. 

A  simple  test  of  considerable  practical  value  for  detecting  a  mixture  of 
dyes  is  as  follows :  Moisten  a  small  sheet  of  paper  with  water,  place  a  little 
of  the  dyestuff  on  one  end  of  the  paper  and  then  blow  the  breath  across  it 
so  as  to  scatter  the  dyestuff  in  fine  particles  over  the  paper.  A  mixture  of 
dyes  will  generally  give  a  mottled  appearance  of  several  colors.     A  modi- 


TESTING   MIXTURES   OF  DYES  669 

fication  of  this  test,  which  at  times  will  yield  better  results,  is  to  place  some 
concentrated  sulphuric  acid  in  a  porcelain  dish,  and  then  sprinkle  a  little 
of  the  suspected  dyestuff  over  the  surface  of  the  acid.  If  particles  of  differ- 
ent dyes  (even  though  they  may  be  of  the  same  color  originally)  are  present 
they  will  generally  show  different  colors  on  contact  with  the  acid,  causing 
them  to  be  easily  detected.  Prepare  a  green  dyestuff  by  making  an  inti- 
mate mixture  of  one  part  Naphthol  Yellow  and  three  parts  Wool  Blue,  and 
test  the  mixture  so  obtained  by  the  two  methods  just  given. 

A  further  method  of  testing  depends  on  the  difference  in  the  capillari- 
ties of  the  two  dyestuffs  when  in  solution.  A  portion  of  the  suspected  dye- 
stuff  is  dissolved  in  water  and  a  single  drop  of  the  solution  placed  on  a  piece 
of  filter  (or  blotting)  paper.  If  the  dyestuff  is  a  mixture,  two  rings  of  color 
will  generally  be  observed  as  the  drop  of  solution  spreads  out  over  the  paper. 
Test  the  green  mixed  dyestuff,  as  prepared  above,  in  this  manner,  and 
observe  the  result.  Sometimes  this  test  may  be  rendered  more  distinct  by 
using  an  alcoholic  solution  of  the  dyestuff.  Make  this  test  with  a  drop 
from  an  alcoholic  solution  of  a  mixture  of  Methyl  Violet  and  Safranine. 

3.  To  Determine  the  Class  to  which  a  Dyestuff  Belongs. — It  is  often 
desirable  to  ascertain  the  chemical  character  of  a  sample  of  unknown 
dyestuff;  that  is  to  say,  the  classification  of  a  coloring  matter  with  reference 
to  its  dyeing  properties.  With  reference  to  these  properties,  nearly  all 
dyes  may  be  broadly  classified  into  four  general  groups,  as  follows : 

(a)  Acid  dyes,  including  those  that  are  dyed  in  an  acid  bath  and  which 
consist  of  the  salts  of  color  acids. 

(h)  Basic  dyes,  including  those  that  are  dyed  in  neutral  or  alkaline 
baths,  and  which  consist  of  the  salts  of  color  bases. 

(c)  Substantive  dyes,  including  those  that  dye  both  animal  and  vege- 
table fibers,  and  which  consist  principally  of  benzidine  and  allied  deriva- 
tives. 

(d)  Mordant  dyes,  including  those  that  do  not  dye  either  the  animal  or 
vegetable  fibers  directly,  but  which  form  color-lakes  with  various  metallic 
oxides.  These  dyes  consist  mostly  of  anthracene  derivatives  and  allied 
compounds  of  an  phenolic  nature.  This  classification,  however,  must  not 
be  taken  as  absolute  and  rigid,  as  one  class  may  merge  into  another  in 
ahnost  an  imperceptible  manner,  and  there  are  dyestuffs  which  exhibit 
the  characteristics  of  more  than  one;  for  instance,  there  are  dyes  which 
may  be  dyed  in  an  acid  bath,  and  would  consequently  be  considered  as 
acid  dyes,  but  which  also  dye  on  metallic  mordants,  and  hence  would  also 
be  included  among  the  mordant  colors. 

Again,  basic  dyes  may  also  be  dyed  in  baths  more  or  less  strongly  acid; 
and  substantive  dyes  may  be  dyed  (on  wool,  for  instance)  from  neutral, 
acid,  or  alkaline  baths,  or  may  even  be  dyed  on  mordants.  So  it  may  be 
seen  that  it  is  not  such  a  simple  matter,  after  all,  to  quickly  decide  as  to 


670 


TESTING   OF   DYESTUFFS 


what  class  a  dycstuff  is  to  be  referred.  This  prol)lein  can  only  be  solved  by 
a  series  of  systematic  tests,  which  should  be  carried  out  in  the  following 
manner : 

A  solution  of  the  dyestuff  should  be  made  of  a  strength  of  about  5  grams 
per  liter,  using  distilled  water  as  the  solvent.  The  solution  is  best  made  bj' 
first  boiling  the  coloring  matter  with  about  200  cc.  of  the  water  for  ten  to 
fifteen  minutes,  and  then  diluting  the  solution  to  1  liter  by  the  addition 
of  cold  water.  The  following  dye-tests  are  then  carried  out  with  this 
solution : 

(a)  A  test  skein  of  scoured  woolen  yarn  is  mordanted  bj-  boiling  for 
one-half  hour  in  a  bath  containing  3  per  cent  of  chrome  and  4  per  cent  of 
tartar;  washed  well,  and  then  dyed  in  a  bath  containing  1  per  cent  of  the 
dyestuff.     If  a  skein  of  woolen  j^arn  becomes  dj-ed,  and  especially  if  most 


Fig.  295. — Spray  Moistening  Machine  for  Finishing  Cottons  and  Linens. 

of  the  color  is  extracted  from  the  bath,  the  dyestuff  in  question  may  ])elong 
to  the  mordant-dyeing  class,  though  the  certainty  of  this  can  only  be 
ascertained  by  the  succeeding  tests.  If,  however,  the  skein  in  this  test 
does  not  become  dyed,  which  is  hardly  likel}',  then  it  is  positively  known 
that  the  coloring  matter  inulcr  examination  is  not  a  mordant  dye. 

(b)  A  second  test  skein  of  woolen  yarn  is  dyed  in  a  bath  containing  10 
per  cent  of  glaubersalt  and  4  per  cent  of  sulphuric  acid,  together  with  1 
per  cent  of  the  dyestuff;  the  material  is  boiled  for  one-half  hoiu',  then 
squeezed  out  and  washed  well.  If  the  wool  remains  undye<l  in  this  case, 
but  was  dyed  in  a  test  (a),  almost  positive  assurance  is  afforded  that  the 
coloring  matter  in  question  is  a  mordant  dyestuff.  If,  however,  the  wool  is 
6yed.  the  coloring  matter  may  be  either  an  acid  dyestuff  belonging  to  the 


DETERMINING  IDENTITY  OF  DYESTUFFS  671 

after-chromed  variety,  or  it  might  also  be  a  basic  or  a  substantive  dye. 
This  must  be  determined  by  the  subsequent  tests. 

If  the  result  of  these  two  tests  leads  to  the  indication  of  a  mordant  dye- 
stuff,  this  may  be  confirmed  by  boiling  a  few  cubic  centimeters  of  the  dj-e 
solution  with  separate  solutions  of  chromium  acetate  and  aluminium 
sulphate;  if  the  dycstuff  belongs  to  the  mordant  class,  there  will  be  a  pre- 
cipitate of  a  color-lake  in  each  case.  If  there  is  no  precipitate,  this  would 
indicate  that  any  dyeing  obtained  on  the  mordanted  wool  in  test  (a)  does 
not  proceed  from  the  presence  of  a  mordant  dye.  If  the  skeins  are  dyed 
in  both  tests  (a)  and  (6),  and  the  dyestuff  solution  also  causes  the  precip- 
itation of  a  color-lake  with  the  salts  of  chromium  and  aluminium,  then  it 
may  reasonably  be  concluded  that  the  coloring  matter  in  question  is  a  mor- 
dant dyestuff  which  also  dyes  wool  from  an  acid  bath.  If  no  color-lake, 
however,  is  formed  wdth  the  metallic  salts,  then  the  dyestuff  is  probably 
an  acid  color. 

(c)  A  test  skein  of  woolen  yarn  is  dyed  in  a  bath  containing  1  per  cent 
of  the  dyestuff  and  10  per  cent  of  glaubersalt,  being  boiled  for  one-half 
hour  then  squeezed  and  washed  well.  If  the  wool  remains  undyed  in  this 
case,  it  indicates  a  mordant  dye,  as  in  the  previous  test  (there  are,  however, 
certain  substantive  dyes  which  leave  wool  practically  undyed  under  such 
conditions,  and  consequently,  before  judging  definitely  that  the  dyestuff 
belongs  to  the  mordant  class,  the  fact  should  be  confirmed,  as  before 
described,  by  the  precipitation  of  the  metallic  color).  If  the  skein  remains 
undyed  in  this  test,  but  was  dyed  in  test  (6),  the  dyestuff  is  probably  an 
after-treated  mordant  dye.  If  the  skein  is  dyed  in  test  (c),  it  may  be  either 
an  acid,  substantive,  or  basic  dye.  If  the  first,  it  would  also  have  been 
dyed  in  test  (h) . 

(d)  A  skein  of  cotton  yarn  is  dyed  in  a  bath  containing  1  per  cent 
of  the  dyestuff  and  10  per  cent  of  cozumon  salt;  boil  for  one-half  hour,  then 
squeeze,  and  wash  well  in  water,  and  then  in  a  dilute  lukewarm  soap  bath. 
If  the  cotton  is  not  dyed,  the  dye  may  belong  to  either  the  mordant, 
the  acid,  or  the  basic  class.  If  to  the  first,  its  nature  would  have  already 
been  indicated  by  the  previous  test.  If  to  the  second,  it  would  also  have 
dyed  the  wool  in  test  (6) ,  and  probably  in  test  (c) .  If  to  the  tliird,  the  wool 
in  test  (c),  and  probably  also  in  test  (6),  would  have  been  dyed.  If  the 
cotton  skein,  however,  in  this  test  is  well  dyed  and  retains  its  color  after 
soaping,  it  indicates  that  the  dyestuff  under  examination  belongs  to  the 
substantive  class. 

(e)  A  skein  of  cotton  yarn  is  worked  in  a  bath  containing  4  per  cent  of 
tannic  acid  for  one-half  hour  at  180°  F.,  then  squeezed  and  worked  for 
ten  minutes  in  a  cold  bath  containing  2  per  cent  of  tartar  emetic,  then 
squeezed  and  well  washed.  This  mordanted  cotton  skein  is  then  dyed  in  a 
bath  containing  1  per  cent  of  the  dyestuff  for  one-half  hour  at  160°  F. 


672  TESTING   OF   DYESTUFFS 

after  which  it  is  squeezed  and  well  washed.  If  the  cotton  becomes  dyed 
in  this  t€st,  and  the  dj'ebath  is  rapidly  and  rather  completely  exhausted, 
the  dyestuff  may  be  regarded  as  a  basic  dye,  in  which  case  the  wool  in 
test  (c)  would  also  be  dyed,  though  with  some  basic  dj'es  only  slightly 
so,  and  the  cotton  in  test  (d)  would  remain  practicallj-  undyed.  If  the 
cotton  skein  in  this  test  remains  undyed  or  is  only  slightly  dyed,  the  dye 
may  be  either  an  acid  or  a  mordant  color,  the  distinction  between  which 
would  have  alread}^  been  made  in  the  previous  tests. 

4.  Chemical  Method  of  Distinguishing  between  Acid  and  Basic  Dye- 
stuff. — These  two  classes  of  dyes  may  be  rather  easily  distinguished  by 
certain  chemical  tests  as  follows: 

(1)  Basic  dyes  are  not  removed  from  an  acidulated  aqueous  solution 
by  agitation  with  ether,  whereas  acid  dyes  are  taken  up  by  the  latter. 
Carry  out  the  test  as  follows:  Take  a  small  quantity  of  Acid  Violet  (a 
portion  the  size  of  a  grain  of  wheat  is  sufficient),  and  dissolve  in  about  5  cc. 
of  dilute  sulphuric  acid;  then  add  5  cc.  of  ether  and  shake  well.  After 
settUng,  notice  that  the  layer  of  ether  has  taken  up  the  coloring  matter, 
showing  the  presence  of  an  acid  dj'e.  Repeat  the  test,  using  ]\Iethylene 
Blue,  and  notice  that  the  ethereal  layer  is  not  colored.  A  sample  contain- 
ing a  mixture  of  acid  and  basic  dye  (which,  however,  is  hardly  likeh',  as 
dyes  of  different  classes  are  seldom  mLxed  together)  may  be  completely 
separated  by  this  test,  the  acid  dj-e  being  completely  extracted  by  the  ether. 

(2)  Caustic  soda  precipitates  most  basic  dj-es  from  their  aqueous  solu- 
tions (the  safranine  class  excepted),  whereas  acid  dyes  are  not  so  precip- 
itated. Take  about  5  cc.  of  an  aqueous  solution  of  Acid  Violet  in  a  test- 
tube,  add  about  5  cc.  of  caustic  soda  solution  (1  :  10)  and  warm  gently. 
Notice  that  the  solution  remains  clear.  Repeat  the  test,  using  a  solution 
of  Magenta,  and  notice  that  a  precipitate  is  formed.  Repeat  the  test  again, 
using  a  dilute  solution  of  Safranine,  and  notice  that  no  precipitate  is  pro- 
duced. (In  the  latter  test,  if  a  concentrated  solution  of  Safranine  is  used,  a 
precipitate  will  form.) 

(3)  Aqueous  solutions  of  basic  dyes  are  precipitated  by  addition  of  the 
so-called  "  tannin  reagent,"  whereas  acid  dyes  are  not  so  precipitated. 
This  is  probably  the  best  means  of  separating  basic  from  acid  dj'es.  The 
tannin  reagent  is  prepared  by  dissolving  25  grams  of  tannic  acid  and  25 
grams  of  sodium  acetate  in  250  cc.  water.  Add  a  few  drops  of  this  reagent 
to  a  dilute  (1  per  cent)  solution  of  Acid  Violet  and  warm  gently;  notice 
that  no  precipitate  is  formed.  Repeat  the  test,  using  a  dilute  solution  of 
IMagenta;   the  latter  will  produce  a  precipitate. 

Test  several  samples  of  unknown  dyes  in  order  to  determine  whether 
they  belong  to  the  acid  or  the  basic  class. 

5.  Detection  of  Adulterations  in  Dyestuffs. — Commercial  dyestuffs  are 
frequently  adulterated  with  common  salt  (sodium  chloride),  glaubersalt 


DETECTION   OF  SALT   IN   DYESTUFFS  673' 

(sodium  sulphate),  soda  ash  (sodium  carbonate),  dextrin,  starch,  sugar,  and 
Epsom  salts.  The  presence  of  such  substances,  however  does  not  always 
indicate  intentional  adulteration ;  for  in  their  manufacture  many  dyes  are 
"  salted  out  "  from  solution,  or  precipitated  by  strong  brine  solutions,  and 
therefore  would  nearly  always  show  the  presence  of  varying  amounts  of 
common  salt.  Again  in  the  manufacture  of  dyestuffs,  it  is  desirable  to  pre- 
pare products  of  uniform  strength,  and  as  the  different  lots  of  manufactured 
dye  seldom  show  exactly  the  same  strength,  a  definite  standard  must  be 
adopted  to  which  weaker  lots  are  brought  up  by  the  addition  of  a  stronger 
dye  while  too  strong  a  lot  of  dyestuff  is  diluted  to  the  standard  by  the 
addition  of  suitable  neutral  salts.  The  occurrence  of  a  large  proportion  of 
the  above-mentioned  salts  in  the  dyestuff  must,  however,  be  taken  as 
indicating  intentional  adulteration.  For  basic  dyes  sodium  chloride  and 
dextrin  are  chiefly  used;  for  the  acid  dyes  sodium  sulphate  is  employed, 
and  for  the  substantive  dyes  either  sodium  chloride  or  sulphate  may  be 
used.  Dextrin  in  some  cases  is  added  to  increase  the  solubility  of  the 
dyestuff. 

(A)  Detection  of  Sodium  Chloride. — As  silver  nitrate  forms  an  insoluble 
white  precipitate  of  silver  chloride  when  added  to  a  solution  of  common 
salt,  this  reagent  is  used  for  the  test.  In  many  cases  the  test  may  be  carried 
out  by  simply  dissolving  a  small  quantity  of  the  dyestuff  in  water,  adding  a 
few  drops  of  nitric  acid  (to  prevent  the  precipitation  of  any  other  salt  of 
silver  besides  the  chloride),  and  then  a  few  drops  of  a  solution  of  silver 
nitrate,  when  the  production  of  a  white  precipitate  will  indicate  the  pres- 
ence of  a  chloride.  This  method,  however,  is  not  always  reliable,  as  many 
dyestuffs  are  hydrochlorides  of  color-bases  (basic  dyes),  or  give  insoluble 
salts  of  silver,  in  which  cases  the  formation  of  a  white  precipitate  would  not 
necessarily  indicate  the  presence  of  common  salt.  It  is  best  to  ignite  a 
portion  of  the  dyestuff  in  a  porcelain  crucible,  so  as  to  burn  off  all  volatile 
and  organic  matter,  leaving  only  mineral  matter  in  the  ash.  Dissolve  the 
ash  in  water,  add  a  few  drops  of  nitric  acid  and  then  the  silver  nitrate;  a 
white  precipitate  of  silver  chloride  will  be  formed  if  common  salt  is  present. 
A  few  dyes,  such  as  the  Eosins,  leave  chlorides  (or  bromides  or  iodides)  in 
the  ash  after  ignition;  hence  this  test  would  not  be  satisfactory.  For 
such  dyes,  the  aqueous  solution  of  the  coloring  matter  should  be  acidulated 
with  dilute  sulphuric  acid,  then  shaken  up  with  ether.  The  dj^estuff  will 
be  dissolved  out  by  the  ether,  leaving  any  common  salt  which  may  be  pres- 
ent in  the  aqueous  layer.  The  later  may  be  removed  and  tested  with 
silver  nitrate  as  described  above.  If  the  dyestuff  is  soluble  in  alcohol,  the 
coloring  matter  may  first  be  extracted  by  warming  with  this  solvent,  and 
the  test  for  common  salt  may  then  be  made  with  the  residue. 

(1)  Testing  for  Salt  in  Acid  Yellow. — Dissolve  a  small  portion  of  the 
pure  dyestuff  in  water,  add  a  couple  of  drops  of  dilute  nitric  acid  and  a  few 


G74  TESTING   OF   DYESTUFFS 

drops  of  silver  nitrate  solution;  no  precipitate  will  be  produced.  Repeat 
the  test,  using  a  sample  of  the  dyestuff  containing  common  salt,  and  notic? 
the  formation  of  a  white  precipitate  of  silver  chloride  (which  will  be  n.cre 
or  less  colored  by  the  dyestuff). 

(2)  Testing  for  Salt  in  Magenta. — Dissolve  a  small  quantity  of  the  pure 
dye  in  water,  and  test  with  silver  nitrate  as  above.  As  the  dye  itself  is 
the  hydrochloride  of  the  color-base,  a  precipitate  of  silver  chloride  will  be 
formed,  though  no  common  salt  is  present.  Place  a  small  quantity  of  the 
dyestuff  in  a  porcelain  crucible,  and  ignite  until  all  organic  matter  is  com- 
pleteh'  burned  away;  dissolve  the  ash  in  a  small  quantity  of  water  acidu- 


FiG.  296. — Gaufring  and  Embossing  Machine. 

lated  with  a  few  drops  of  nitric  acid,  and  test  with  silver  nitrate;  no  pre- 
cipitate will  be  produced.  Repeat  this  test,  using  a  sample  of  Magenta 
containing  common  salt  and  note  the  formation  of  a  precipitate  of  silver 
cliloride. 

(3)  Testing  for  Salt  in  Eosin. — Place  a  small  quantity  of  pure  Eosin 
in  a  porcelain  crucible  and  ignite  as  above  described ;  on  dissolving  the  ash 
in  water  and  testing  with  silver  nitrate  in  the  usual  manner,  a  precipitate 
will  be  formed  though  no  common  salt  is  present.  Next  take  a  small  quan- 
titj^  of  the  Eosin,  dissolve  in  10  cc.  of  water  in  a  test-tube  (or  better,  a 
stoppered  separator}'  funnel),  add  5  cc.  of  ether  (be  sure  the  solution  is 
cold  before  adding  the  ether),  shake  well  and  allow  to  stand.  The  ethereal 
layer,  containing  the  dyestuff  in  solution  will  collect  on  top,  while  the 
aqueous  layer  will  remain  at  the  bottom.     If  the  color  is  not  well  extracted 


DETECTION   OF   GLAUBERSALT   IN   DYESTUFFS  675 

from  the  bottom  laj^er  pour  off  the  ethereal  layer  and  repeat  the  extraction 
with  fresh  ether.  Withdraw  the  aqueous  layer  by  means  of  a  pipette,  and 
test  it  with  silver  nitrate  as  usual ;  no  precipitate  will  be  produced.  Repeat 
this  test,  using  a  sample  of  Eosin  containing  common  salt,  and  notice 
that  a  precipitate  of  silver  chloride  will  l)e  formed. 

(4)  Testing  for  Salt  in  Orange  II. — Place  a  small  sample  of  the  pure  dye 
in  a  test-tube  and  dissolve  in  10  cc.  of  warm  alcohol;  it  should  be  com- 
pletely soluble.  Repeat  this  test,  using  a  sample  of  the  dye  containing 
common  salt ;  notice  that  a  residue  is  left.  Dissolve  this  in  water  and  test 
with  silver  nitrate  as  usual;  a  precipitate  of  silver  chloride  will  be  produced. 

(B)  Detection  of  Sodium  Sulphate. — Sulphates  in  general  are  detected 
by  the  addition  of  barium  chloride  to  their  solution,  whereby  an  insoluble 
white  precipitate  of  bariinn  sulphate  is  formed.  The  presence  of  sulphates 
in  the  ash  of  a  dyestuff  does  not  necessarily  indicate  adulteration  with 
glaubersalt,  as  many  dyes  are  themselves  sulphonated  compounds,  and  on 
ignition  leave  sodium  sulphate  in  the  ash.  The  best  procedure  for  testing 
for  glaubersalt  in  a  dyestuff  is  as  follows:  Dissolve  some  pure  Benzopur- 
purine  in  a  small  amount  of  water,  add  a  few  drops  of  dilute  hydrochloric 
acid  (to  prevent  other  compounds  of  barium  being  precipitated),  then  a 
solution  of  barium  chloride  as  long  as  a  precipitate  forms.  This  precipitate, 
which  consists  of  barium  sulphonate,  is  filtered  off,  washed,  and  boiled 
with  a  solution  of  ammonium  carbonate.  This  converts  it  into  barium 
carbonate;  filter  again,  and  wash  the  residue  of  barium  carbonate,  and  then 
add  dilute  hydrochloric  acid  to  the  latter,  when  it  should  be  completely 
dissolved.  Repeat  the  test,  using  a  sample  of  Benzopurpurine  containing 
glaubersalt.  The  precipitate  obtained  with  barium  chloride,  in  this  case, 
consists  of  a  mixture  of  barium  sulphonate  and  barium  sulphate.  On  boil- 
ing this  with  ammonium  carbonate,  only  the  sulphonate  is  converted  into 
barium  cabonate,  and  on  finally  dissolving  in  hydrochloric  acid,  the  barium 
sulphate  will  be  left  as  an  insoluble  residue,  thus  showing  the  presence  of 
glaubersalt  in  the  original  dye.  Another  method  for  testing  for  sulphates 
is  to  precipitate  the  dyestuff  from  its  aqueous  solution  by  the  addition  of 
pure  common  salt  to  complete  saturation.  The  precipitated  dyestuff  with 
excess  of  salt  is  filtered  off,  the  filtrate  acidulated  with  a  few  drops  of  hydro- 
chloric acid  and  tested  with  barium  chloride  solution.  The  formation  of  a 
white  precipitate  will  indicate  the  presence  of  glaubersalt  in  the  original 
dyestuff.  This  method,  however,  is  not  very  satisfactory,  as  it  is  usually 
difficult  to  precipitate  the  dyestuff  completely'  from  its  solution.  Another 
method  of  testing  for  sulphates  is  to  dissolve  the  dyestuff  in  strong  warm 
alcohol  (where  this  is  possible),  and  as  glaubersalt  is  insoluble  in  alcohol 
it  will  be  left  as  a  white  residue  (as  in  the  case  of  common  salt).  This  is 
to  be  dissolved  in  water  and  tested  with  barium  chloride  in  the  usual 
manner. 


676  TESTING  OF  DYESTUFFS 

(C)  DeteQtion  of  Soda  Ash. — This  substance  is  frequently  added  to 
Eosins,  and  sometimes  to  substantive  dyes.  It  is  detected  b}'  dissolvii  g  a 
sample  of  the  dye  m  water,  and  adding  hydrochloric  acid  to  the  solution 
when  an  effervescence  will  be  produced  due  to  the  liberation  of  carbon 
dioxide  gas  from  the  carbonate  present.  For  example:  Dissolve  some  pure 
Eosin  in  a  little  water  and  add  a  few  drops  of  dilute  hydrochloric  acid; 
no  effervescence  will  occur.  Repeat  the  test,  using  a  sample  of  Eosin 
containing  sodium  carl)onate;  a  vigorous  effervescence  will  be  noted. 

(D)  Detection  of  Epsom  Salts. — This  consists  of  magnesium  sulphate, 
and  is  occasionaly  added  as  an  adulterant  to  dyes.  The  presence  of 
the  sulphate  is  detected  in  the  manner  described  under  the  test  for  sodium 
sulphate.  The  presence  of  the  magnesium  is  shown  in  the  following 
manner:  Place  a  portion  of  IMethyl  Violet  containing  magnesium  sulphate 
in  a  porcelain  crucible;  ignite  until  all  carbon  and  volatile  matter  is  burned 
away.  Dissolve  the  ash  in  hot  dilute  hydrochloric  acid,  and  filter,  if 
necessary.  Neutralize  the  filtrate  with  ammonia  water  and  add  a  solution 
of  sodium  phosphate.  After  standing  for  a  short  time  a  crj'stalline  pre- 
cipitate (of  magnesium  ammonium  phosphate)  is  formed,  showing  the 
presence  of  a  magnesium  salt  in  the  original  d^'estuff. 

(E)  Detection  of  Dextrin. — This  impurity  can  usually  be  recognized 
by  the  peculiar  odor  dextrin  gives  on  dissolving  the  dye  in  warm  water. 
It  may  best  be  tested  for  as  follows:  Take  a  small  sample  of  IMethyl 
Violet  containing  dextrin;  extract  the  coloring  matter  with  absolute 
alcohol;  the  dextrin  will  be  left  as  a  residue.  Dissolve  the  latter  in  a 
small  quantity  of  warm  water  and  notice  the  peculiar  odor  of  the  dissolving 
dextrin.     Dextrin  is  frequently  adtlcd  to  paste  dyes  and  to  basic  dyes. 

(F)  Detection  of  Starch. — This  impurity  may  be  separated  from  the 
dyestuff  by  treating  with  cold  water,  in  which  the  starch  is  insoluble.  It 
may  then  be  recognized  as  follows:  Take  a  sample  of  Eosin  containing 
starch;  extract  the  coloring  matter  with  cold  water;  dissolve  the  residue 
of  starch  in  a  little  boiling  water,  and  add  a  few  drops  of  a  solution  of  iodine 
in  potassium  iodide.  A  deep  blue  color  will  be  produced,  indicating  the 
presence  of  starch. 

(G)  Detection  of  Sugar. — This  impurity  is  frequently'  added  to  crystalline 
dyes,  as  it  occurs  in  the  crystalline  form  itself.  Its  presence  maj^  be  shown 
as  follows:  Take  a  sample  of  Magenta  containing  sugar;  extract  with 
absolute  alcohol.  The  dyestuff  passes  into  solution,  whereas  the  sugar 
remains  practically'  insoluble,  and  becomes  nearly  colorless.  Heat  the 
residue  in  a  test-tube  and  notice  the  odor  of  caramel,  indicating  the  presence 
of  sugar. 

6.  Determination  of  the  Capillary  Speed  of  Dyestuff s. — By  the  capillary 
speed  of  a  dyestuff  is  meant  the  height  to  which  its  solution  will  rise  in 
a  given  time  through  porous  paper  (filter  or  blotting  paper).     This  factor 


CAPILLARY   SPEED   OF  DYESTUFFS 


677 


is  only  a  relative  number,  and  is  usually  compared  with  pure  water  as  a 
standard. 

Take  five  strips  of  blotting  paper  measuring  5  ins.  in  length  and  |  in. 
in  width;  make  a  mark  on  each  strip  1  in.  from  the  end.  Immerse  one  of 
these  strips  in  a  small  beaker  containing  pure  water  so  that  the  surface  of 
the  water  comes  exactly  to  the  1-in.  mark  on  the  paper.  Sustain  the  strip 
in  a  perpendicular  position,  and  allow  it  to  remain  in  the  water  for  just  one 
minute.  Then  measure  the  height  to  which  the  water  has  risen  on  the 
paper.  Repeat  the  test  with  a  fresh  strip  of  paper,  using  a  1  per  cent  solu- 
tion of  Magenta,  and  after' one  minute  measure  the  height  to  which  the 
color  has  ascended.  Repeat  the  test  further  on  1  per  cent  solutions  of 
Naphthol  Yellow,  Acid  Violet,  and  Malachite  Green.  Tabulate  the  results 
obtained  as  follows : 


Solution. 

Distmc?  Color 

Risi-s. 

Compared  with 
Water  as  =100. 

Water 

100 

Magenta 

Naphthol  Yellow  S 

Acid  Violet 

Malachite  Green 

CHAPTER   XXX 

MISCELLANEOUS  TESTS  IN  DYEING 

1.  The  Amounjt  of  Dyestiiff  Necessary  for  a  Full  Shade. — This  factor 
may  be  deftermined  by  dyeing  test  skeins  with  increasing  amounts  of  dye- 
stuff  until  no  further  increase  in  shade  is  observed.  Proceed  as  follows: 
Use  six  test  skeins  of  woolen  j-arn  (No.  1  to  Xo.  6)  of  the  same  weight,  dye 
them  respectively  with  the  following  amounts  of  Acid  Violet,  employing 
the  usual  acid  bath  and  method  of  dyeing: 


No.  1,  with  1  per  cent  of  dyestuff 
No.  2,  with  2  per  cent  of  dyestuff 
No.  3,  with  3  per 'cent  of  dyestuff 
No.  4,  with  4  per  cent  of  dyestuff 
No.  5,  with  5  per  cent  of  dyestuff 
No.  6,  with  6  per  cent  of  dyestuff 


After  dj-eing  the  samples  are  compared,  and  note  is  taken  at  which  point 
the  shade  ceases  to  show  a  perceptible  increase.  The  same  method  maj'  be 
employed  in  other  classes  of  dyes,  using  their  respective  methods  of  dyeing. 
2.  To  Determine  the  Degree  of  Exhaustion  of  the  Dyebath. — By  the 
exhaustion  of  the  dyebath  is  meant  the  relative  quantity  of  color  absorbed 
by  the  fiber  during  the  dyeing  process.  Proceed  as  follows:  Dye  a  test 
skein  of  woolen  yarn  with  3  per  cent  of  Acid  Violet,  4  per  cent  of  sulphuric 
acid,  20  per  cent  of  glaubersalt,  making  the  d5'ebath  up  to  exactly  300  cc. 
and  taking  out  25  cc.  of  the  solution  before  dyeing  to  preserve  for  com- 
parison in  a  test-tube.  Carrj-  out  the  dyeing  operation  in  the  usual  manner ; 
squeeze  the  excess  of  liquor  from  the  skein  back  into  the  dyebath  so  as  not 
to  lose  any  of  the  solution.  ]\Iake  up  the  bath  again  to  exactly  275  cc; 
fill  a  graduated  colorimetric  tube  with  this  solution;  take  1  cc.  of  the 
original  d3'ebath  in  another  smiilar  colorimetric  tube,  and  dilute  the  latter 
\^-ith  water  until  it  exhibits  the  same  intensity  of  color  as  the  first  tube. 
The  degree  of  dilution  required  measures  the  degree  of  exhaustion  of  the 
dyebath.  For  example:  1  cc.  of  the  original  solution  required  to  be  diluted 
to  8.5  cc.  to  show  the  same  intensity  of  color  as  the  exhausted  bath;  hence 
the  relative  amount  of  dye  left  in  the  bath  is  1^-8.5  =  0.12,  and  the  amount 

678 


TESTING  EXHAUSTION   OF  DYEBATH  679 

absorbed  must  have  been  0.88  or  88  per  cent.  Therefore  the  degree  of 
exhaustion  in  this  case  would  be  88  per  cent. 

Pour  the  hquor  taken  from  the  exhausted  bath  back  into  the  dye-bath, 
and  without  further  addition  of  dyestuff  or  chemicals,  dye  another  test 
skein  of  woolen  yarn.  After  dyeing  dry  a  portion  and  compare  it  with  the 
first  skein.  The  difference  in  intensity  of  the  two  dyeings  will  represent  in  a 
rough  manner  the  degree  of  exhaustion.  Now  continue  the  dyeing  of  the 
second  skein  by  adding  to  the  bath  sufficient  dyestuff  to  bring  the  shade  up 
to  that  of  the  first  skein.  Besides  the  dyestuff  also  add  2  per  cent  more  of 
sulphuric  acid,  as  some  of  the  acid  originally  added  will  have  been  removed 
by  the  first  dyeing.  Note  the  amount  of  dyestuff  added,  and  this  will 
represent  the  amount  originally  absorbed  from  the  first  bath.  For  exam- 
ple: it  required  the  further  addition  of  2.5  per  cent  of  Acid  Violet  to  match 
the  second  dyeing  to  the  first ;  hence,  the  degree  of  exhaustion  would  be 
2.5-4-3X100  =  83.3  per  cent,  which  is  a  rather  close  approximation  to  the 
result  obtained  by  the  first  method.  The  first  method  is  the  more  accurate, 
but  in  some  cases  the  bath  after  dyeing  has  a  different  color  from  that  of 
starting,  and,  again,  some  dyes  (mordant  colors)  give  solutions  which  do 
not  accurately  represent  the  color  obtained  by  dyeing;  in  which  cases  the 
latter  method  only  could  be  used. 

3.  To  Determine  the  Correct  Amount  of  Mordant  to  Use, — Mordant 
six  test  skeins  of  woolen  yarn  each  with  4  per  cent  of  tartar  and  the  following 
amounts  of  chrome: 

(1)  1  per  cent  (4)  5  per  cent 

(2)  2  per  cent  (5)  8  per  cent 

(3)  3  per  cent  (6)   12  per  cent 

Enter  at  140°  F.,  raise  to  boiling,  and  mordant  for  forty-five  minutes; 
wash,  and  dye  the  skeins  all  together  with  3  per  cent  of  Alizarine  Red 
in  the  usual  manner.  Rinse  and  dry.  Compare  the  several  skeins,  and 
by  selecting  the  best  color  thus  determine  which  percentage  of  chrome  is 
the  proper  one  to  use.  For  nearly  all  purposes  of  mordanting  it  has  been 
found  that  about  3  per  cent  of  chrome  gives  the  best  results.  A  larger 
amount  of  chrome  appears  to  oxidize  the  wool  and  causes  bad  shades  in 
dyeing;  this  is  known  as  over-chroming  and  the  wool  becomes  harsh 
and  brittle. 

4.  To  Determine  the  Degree  of  Exhaustion  of  the  Mordant  Bath. — 
Mordant  a  test  skein  of  woolen  yarn  in  a  bath  containing  300  cc.  of  water, 
3  per  cent  of  chrome,  4  per  cent  of  tartar.  Enter  at  140°  F.,  raise  to  boiling, 
and  mordant  for  forty-five  minutes.  Squeeze  back  the  liquor  from  the 
skein  into  the  bath  and  wash  well.  Add  sufficient  water  to  the  mordant 
bath  to  bring  its  volume  up  to  300  cc.  again,  and  without  further  additions, 
mordant  a  second  skein  in  a  similar  manner.     Repeat  in  the  same  way  with 


680 


MISCELLANEOUS   TESTS   IX   DYEING 


a  tliird  skein.  Then  dye  the  three  skeins  together  with  3  per  cent  Ahzarine 
Red  in  the  usual  manner,  and  finally  compare  the  skeins  for  depth  of  shade 
in  order  to  determine  the  relative  exhaustion  of  the  mordant  bath. 

Repeat  this  test,  using  a  mordanting  bath  of  300  cc.  of  water,  3  per 
cent  of  chrome,  2  per  cent  of  lactic  acid,  2  per  cent  of  sulphuric  acid.  jMor- 
dant  three  test  skeins  successiveh'  in  the  manner  above  described  and  dj-e 
again  with  3  per  cent  of  Ahzarine  Red.  Compare  these  for  depth  of  shade 
to  determine  the  relative  exhaustion  of  the  bath  and  also  to  determine  if 
the  exhaustion  is  the  same  in  the  second  case  as  in  the  first. 


Fig.  297.— Calender  for  Giving  Silk  Finish  on  Cotton  Cloth. 

5.  To  Show  the  Dichroic  Property  of  a  Dyestufif. — Coloring  matters 
are  known  as  "  dichroic  "  when  they  change  their  tone  with  change  of 
intensity.  Magenta,  for  instance,  in  heaw  shades  is  a  red  color,  while  in 
light  tints  it  changes  to  a  bluish  pink.  To  show  this  property  proceed 
as  follows:  Dye  six  skeins  of  woolen  yarn  with  jNIagenta,  using  10  per  cent 
of  glaubersalt  in  each  dyebath  together  with  the  following  amounts  of 
dyestuff  : 

(1)  3  per  cent  (4)  0.5    per  cent 

(2)  2  per  cent  (5)  0.1    per  cent 

(3)  1  per  cent  (6)  0.01  per  cent 

Enter  at  100°  F.,  raise  to  180°  F.,  and  dye  for  thirty  minutes.     Observe 
the  different  tones  in  the  colors  obtained  with  change  of  concentration. 

The  dichroic  nature  of  a  coloring  matter  may  also  be  observed  with  its 
solution.     Take  a  small  quantity  of  JNIagenta  and  dissolve  in  5  cc.  of  water 


DICHROIC   PROPERTIES   OF   DYES  681 

in  a  test-tube;  pour  out  half  of  this  sohition  into  a  second  test-tube  and 
dilute  with  an  equal  quantity  of  water.  Pour  out  half  of  the  second  solu- 
tion into  a  third  test-tube,  and  dilute  again  with  four  times  the  amount  of 
water.  Compare  the  colors  of  the  three  solutions,  and  notice  the  effect  of 
dilution  on  the  tone  of  the  original  color.  In  the  same  manner  test  the 
dichroic  properties  of  Eosin,  Methyl  Violet,  and  Malachite  Green. 

6.  Effect  of  Dichroism  in  the  Compounding  of  Shades. — Dye  a  test 
skein  of  woolen  yarn  with  3  per  cent  of  Auramine,  and  another  with  3  per 
cent  of  Magenta.  Then  dye  two  more  skeins,  the  one  with  yo  per  cent  of 
Auramine  and  the  other  with  xV  per  cent  of  Magenta.  Notice  that  the 
Auramine  is  not  especially  dichroic,  whereas  the  Magenta  is  markedly  so. 
Now  dye  a  skein  with  a  mixture  of  2  per  cent  of  Auramine  and  3  per  cent 
of  Magenta,  and  another  skein  with  2  per  cent  of  Auramine  and  1  per  cent 
of  Magenta,  and  a  third  skein  with  2  per  cent  of  Auramine  and  tV  per  cent 
of  Magenta.  Notice  the  wide  difference  in  the  character  of  the  colors 
obtained;  for  while  the  Magenta  in  the  first  case  (3  per  cent)  excercises 
the  function  of  a  red  dye,  in  the  last  case  (to  per  cent)  it  acts  as  a  violet 
dyestuff ;  hence  the  effect  is  entirely  different  in  kind.  Next  dye  a  skein 
with  To  per  cent  of  Auramine  and  -to  per  cent  of  Magenta,  and  another  skein 
with  2  per  cent  of  Auramine  and  2  per  cent  of  Magenta.  Theoretically, 
the  first  color  should  be  a  reduced  tint  of  the  second;  but  practically  it 
will  be  seen  that  the  two  colors  are  of  entirely  different  orders.  This  is 
caused  by  the  wide  variation  in  the  color  of  the  Magenta  with  different 
concentrations.  From  this  it  will  be  seen  that  the  dichroic  property  of 
a  dyestuff  has  an  important  bearing  on  its  mixing  qualities  with  other  dyes 
in  the  compounding  of  shades.  A  red  and  a  blue  dye  when  used  together 
in  heavy  shades  may  give  a  very  satisfactory  violet;  but  if  the  attempt 
is  made  to  obtain  a  reduced  tint  of  this  violet  by  using  small  percentages 
of  the  two  colors  in  the  same  proportions,  it  will  perhaps  be  found  that  a 
tint  of  an  entirely  different  color  is  obtained.  The  same  is  true  when  dealing 
with  green  and  orange  colors.  In  order  to  become  acquainted  with  the 
true  mixing  qualities  of  his  dyestuffs,  the  dyer  should  be  familiar  with  the 
colors  they  give  with  large,  medium,  and  small  percentages,  and  in  the 
mixing  of  his  shades  he  must  make  due  allowance  for  the  change  in  tone  of 
color  of  the  dyes  with  varying  concentration. 


CHAPTER  XXXI 
CHEMICAL  REACTIONS  OF  DYESTUFFS 

1.  Identification  of  Dyes. — In  order  to  identify  any  particular  dye- 
stuff  it  is  necessary  to  test  it  with  various  chemical  reagents,  whereby  a 
series  of  chemical  reactions  is  obtained,  usually  based  on  color  changes. 
Tabulated  reactions  have  been  prepared  of  the  various  dyestuffs,  and  by 
reference  to  these  it  is  usually  possible  to  identify  any  individual  coloring 
matter.  Difficulty,  however,  will  be  experienced  with  coloring  matters 
containing  mixtures  of  two  or  more  dyestuffs,  as  the  reaction  of  one  of  the 
dyes  in  the  mixture  may  obscure  the  reaction  of  the  other  dye.  In  the 
case  of  many  mixtures  it  is  practically  impossible  to  determine  accurately 
the  exact  dyestuffs  present  unless  some  method  is  available  for  the  separa- 
tion of  the  dyes. 

Considerable  evidence  as  to  the  identity  of  a  dj^estuff  is  furnished  by  its 
dyeing  properties  toward  cotton  and  wool.  In  this  manner  it  will  be  pos- 
sible to  determine  if  the  dyestuff  in  question  is  acid  or  basic,  etc.,  and  this 
method  of  classification  will  eliminate  many  uncertain  possibilities. 

In  the  following  experiments,  to  illustrate  the  results  of  the  reactions 
given,  the  dyestuff  Auramine  is  taken  as  an  example. 

2.  Solubility  Tests. — (a)  With  Water. — Take  about  0.1  gram  of  the 
dyestuff  and  add  to  20  cc.  of  distilled  water  in  a  test-tube;  shake  well,  and 
then  boil;  observe  the  relative  solubility.  Auramine  is  very  soluble. 
(b)  With  Alcohol. — Repeat  the  test,  using  alcohol  in  place  of  water;  note 
the  relative  solubility  and  the  color  of  the  solution.  Auramine  is  very 
soluble  with  a  yellow  color,  (c)  With  Ether. — Repeat  the  test,  using 
ether;  Auramine  is  insoluble,  (d)  With  Benzene. — Repeat  the  test, 
using  benzene;  Auramine  is  insoluble. 

3.  Reaction  with  Sulphuric  Acid. — (a)  With  Concentrated  Acid. — A 
small  quantity  (on  the  tip  of  a  penknife  blade)  of  the  dyestuff  is  added  to 
about  5  cc.  of  pure  concentrated  sulphuric  acid  in  a  test-tube;  shake 
well  and  note  the  color  of  the  solution  obtained.  Auramine  dissolves  with 
effervescence  (due  to  evolution  of  hydcochloric  acid  gas),  and  gives  a 
colorless  solution.  (6)  Dilution  with  Water. — Add  a  drop  or  two  of  the 
strong  acid  solution  as  obtained  above  to  about  10  cc.  of  water  in  a  test- 
tube,  and  note  the  reaction  which  occurs.     Auramine  on  dilution  gives  a 

682 


REACTIONS   WITH   ACIDS 


683" 


yellow  color,  (c)  On  Heating. — The  remainder  of  the  strong  acid  solution 
is  gradually  heated  to  the  boiling  point.  Auramine  furnishes  a  pale  brown- 
ish yellow  solution. 

4.  Reaction  with  Hydrochloric  Acid. — Use  an  aqueous  solution  of  the 
dyestuff  containing  1  gram  of  dye  per  liter.  To  5  cc.  of  this  solution  add 
5  cc.  of  a  solution  of  hydrochloric  acid  (containing  100  cc.  of  the  strong  acid 
per  liter);  allow  to  stand  for  ten  minutes,  and  note  what  reaction,  if  any, 
occurs.  Auramine  remains  unchanged.  Now  heat  the  solution  to  boiling 
and  note  any  change  that  occurs;  Auramine  becomes  decolorized. 


Fig.  298. — Beetling  Machine  for  Heavy  Linens  and  Cottons. 

5.  Reaction  with  Nitric  Acid. — To  5  cc.  of  the  aqueous  solution  of  the 
dyestuff  add  5  cc.  of  a  solution  of  nitric  acid  (containing  50  cc.  of  the  strong 
acid  per  hter),  and  carry  out  the  test  as  above.  Auramine  remains  un- 
changed cold;  boiling  it  gives  a  pale  yellow  solution. 

6.  Reaction  with  Sodium  Hydrate. — Carry  out  the  test  as  above 
described,  using  5  cc.  of  a  solution  of  sodium  hydrate  (containing  100  cc.  of 
sodium  hydrate  of  sp.  gr.  1.3  to  1  Hter).  If  a  precipitate  is  formed,  add 
about  2  cc.  of  ether,  and  shake;  observe  if  the  ether  extracts  the  precip- 
itated color  from  the  caustic  soda;  then  add  a  drop  or  two  of  acetic  acid  to 
the  ethereal  layer,  and  note  any  change.  Auramine  gives  a  white  precipitate, 
extracted  with  ether,  becoming  yellowish  on  addition  of  acetic  acid. 

7.  Reaction  with  Ammonia. — Repeat  the  test  as  above  given,  using 
S  cc.  of  commercial  ammonia  water.  Auramine  undergoes  the  same  reac- 
tions as  with  sodium  hydrate. 


684  CHEMICAL  REACTIONS   OF   DYESTUFFS 

8.  Reaction  with  Sodium  Carbonate. — Repeat  the  test  as  given  above, 
using  5  cc.  of  a  solution  of  sodium  carbonate  (100  grams  per  liter).  If  a 
precipitate  is  formed  with  the  cold  solution,  heat  to  boiling  and  observe  if 
this  causes  the  precipitate  to  redissolvc.  Auramine  gives  a  milky  yellow 
precipitate  which  remains  insoluble  on  heating. 

9.  Reaction  with  Tannin  Reagent. — Carry  out  the  test,  using  5  cc.  of  a 
solution  containing  100  grams  of  tannic  acid  dissolved  in  500  cc.  of  water 
and  mixed  with  a  solution  of  100  grams  of  sodium  acetate  in  500  cc.  of 
water.  If  a  precipitate  is  formed  heat  to  boiUng  and  note  any  change  in  its 
character.  Auramine  gives  a  yellow  precipitate,  which,  on  boiling,  becomes 
brown,  resinous,  and  partially  soluble.  This  reagent  is  useful  for  distin- 
guishing between  acid  and  basic  dyes,  as  the  latter  alone  give  a  precipitate. 

10.  Reaction  with  Alum. — Add  to  the  aqueous  solution  of  the  dycstuff 
5  cc.  of  a  solution  of  alum  (containing  50  grams  per  liter).  If  a  precipitate 
is  formed,  heat  to  boiling,  and  note  any  change  that  may  occur.  Aura- 
mine remains  unchanged  with  the  alum  solution.  Many  of  the  acid 
dyes  and  nearly  all  of  the  mordant  dyes  give  characteristic  precipitates 
with  alum. 

11.  Reaction  with  Potassium  Bichromate. — Add  to  the  aqueous  solu- 
tion of  the  dyestuff  5  cc.  of  a  solution  containing  50  grams  of  potassium 
bichromate  per  liter.  If  a  precipitate  is  formed,  heat  to  boiling,  and  note 
any  change  that  may  occur.  Auramine  gives  a  yellow  precipitate,  which 
on  heating  becomes  resinous  and  for  the  most  part  dissolves.  The 
majority  of  the  basic  dyes  are  precipitated  by  this  reagent,  as  is  also 
the  case  with  most  of  the  mordant  dyes;  only  a  few  of  the  acid  dyes  are 
thus  precipitated. 

12.  Reaction  with  Ferric  Chbride. — Add  to  the  aqueous  solution  of  the 
dyestuff  5  cc.  of  a  solution  containing  100  grams  of  ferric  chloride  per  liter; 
note  the  reaction  and  then  heat  to  boiling  and  observe  any  further  change. 
Auramine  remains  unchanged  in  the  cold  solution ;  on  heating  the  solution 
becomes  turbid  and  of  a  brownish  yellow  color. 

13.  Reaction  with  Stannous  Chloride. — Add  to  the  aqueous  solution 
of  the  dyestuff  5  cc.  of  a  solution  containing  100  grams  of  stannous  chloride 
per  liter  (with  sufficient  hydrochloric  acid  to  yield  a  clear  solution) .  After 
standing  ten  minutes,  heat  to  boiling,  and  note  the  reactions  which  occur. 
Auramine  remains  unchanged.  A  large  number  of  dyestuffs  either  give 
characteristic  precipitates,  or  become  decolorized. 

14.  Reaction  with  Bleaching  Powder. — Add  to  the  aqueous  solution  of 
the  dyestuff  5  cc.  of  a  solution  of  bleaching  powder  of  1.5°  Tw.  strength. 
After  standing  for  ten  minutes,  heat  to  boiling,  and  note  any  changes  which 
occur.  Auramine  gives  a  dirty,  pale  yellow  precipitate,  which,  on  heating 
turns  to  a  dirty  red  color. 


REACTIONS   WITH   ZINC   DUST 


685 


15.  Reaction  with  Zinc  Dust. — Add  to  the  aqueous  sohition  of  the  dye- 
stuff  about  1  gram  of  zinc  dust  and  5  cc.  of  annnonia  water;  sliake  well 
and  then  heat  to  boiling;  filter  at  once,  and  note  if  the  filtrate  if  decolorized 
becomes  colored  again  on  exposure  to  the  air.  Auramine  gives  a  colorless 
filtrate,  and  the  color  does  not  reappear  on  exposure  to  the  air;  but  the 
precipitate  left  on  the  filter  gradually  becomes  yellowish  on  standing.  The 
solutions  of  nearly  all  dyes  are  decolorized  by  this  reagent,  and  many  dyes 
give  a  characteristic  reappearance  of  color  on  exposure  to  the  air.  The 
loss  of  color  h  caused  by  the  reduction  of  the  coloring  matter,  which  may 
be  converted  either  into  a  leuco  (colorless)  derivative  (which  allows  of  the 


Fig.  299. — Sizing  Machine  for  Skein  Yarn. 


original  dyestuff  being  again  formed  on  oxidation  in  the  air),  or  be  entirely 
destroyed.  In  the  latter  case  no  reappearance  of  color  will  be  shown  on 
oxidation. 

16.  Reaction  with  Zinc  Dust  and  Acetic  Acid. — Repeat  the  above  test 
as  given,  using,  however,  5  cc.  of  acetic  acid  in  place  of  the  ammonia. 
Auramine  becomes  blue  on  acid  reduction.  Many  dyestuffs  give  char- 
acteristic colors  with  this  test,  while  some  are  decolorized  completely. 
In  many  cases  the  original  colors  reappear  on  exposure. 

Test  the  following  dyestuffs  in  the  same  manner  as  outlined  for  Aura- 
mine : 


Magenta 
Acid  Violet  4R 


Benzopurpurine 
Alkali  Blue 


Naphthol  Yellow  S 
Alizarine  Brown  SO 


686 


CHEMICAL  REACTIONS   OF   DYESTUFFS 


TABULATION  OF  RESULTS  WITH  CHEMICAL  REAGENTS. 


Test. 


Auramine. 


Solubility  in 


Concentrated 
sulphuric 
acid. 


Water. 

Alcohol. 
-Ether  .y: 
—Benzene/ 

Solution. 

Dilution. 

Heating. 


Dilute    hydro-  / 

chloric  acid.  \ 

Dilute      nitric  i 

acid.  I 


Sodium 
drate. 

Ammonia. 


hy- 


A 


mm       car- 
bonate. 


>rTjannin  reagent 


Cold. 
Heating. 
Cold. 
Heating. 
Cold. 

Extraction 
with  ether. 
Cold. 
Cold. 

Heating. 

Cold. 

Heating. 


^t/O 


Alum. 


/  Cold. 
\  Heating. 
Potassium    bi-  f-Cold\ 
chromate.  Heating. 


'Terric  chloride 

Stannous  chlo- 
ride. 

Calcium  hypo- 
chlorite. 

Zinc  dust  and 
ammonia. 

Zinc   dust  and 
acetic  acid. 


Cold. 

Heating. 

Cold. 

Heating. 

Cold. 

Heating. 

Cold. 

E.xposed. 

Precipitate. 

Cold. 

Exposed. 

Precipitate. 


Very  sol. 

Very  sol. 

Insoluble.^ 

Insoluble.  - 

Colorless. 

Yellow. 

Brown-yellow. 

No  change. 
JDjecolorized. 
No  change. 
Pale  yellow. 
White  ppt. 
Color  extracted. 

As  above. 
Yellow       milky 

ppt. 

No  change. 
Yellow  ppt. 
Brown,  resinous; 

partly  sol. 
No  change. 
No  change. 
Yellow  ppt:' 
Resinous ; 

mostly       dis- 
solved. 
No  change. 
Brown-yellow. 
No  change. 
No  change. 

Dirty       yellow 
ppt. 

Dirty  red  color. 
j  Colorless  y 
;  Colorless: 
I  Yellowish. 

NtrChange. 


2. 
Acid  Violet  4R. 


Quite  sol. 
Quite  sol. 
Insoluble; 
Insoluble.. 
Dark  brow^ 
Violet, 

Dark       yellow- 
brown. 
.No  change^ 
No  change.  - 
No  change. 
No  change. 
Colorless. 


Colorless. 


No  change. 
No  change. 

Darker. 
Same. 
No  chang3. 
No  change. 


-^^  change. 
Ne-efeange. 


Colorless. 
Same. 


Blui.sh  pink. 
Same. 


^--/IM 


Alkali  Blue  R. 


d' 


Quite  sol. 
Quite  sol. 
f^ightly  soluble. 
Insoluble.    ", 
Red  brown. 
Blue  ppt. 
Dark  brown. 

Blue  ppt. 
Blue  ppt. 
Blue  pi^t. 
Turns  greer)^ 
No  changed 


No  change. 


Blue  pptX 
Blue  ppt. 

No  cliauge.  -V 


Blue  ppt. 


Colorless. 
Blue. 


-Blue. 


CHAPTER   XXXII 
ANALYSIS   OF  TEXTILE  FABRICS 

1.  To  Determine  the  Amount  of  Wool  and  Cotton  in  a  Fabric. — A 

weighed  portion  of  the  air-dry  sample  is  boiled  for  ten  minutes  in  a  5 
per  cent  solution  of  caustic  potash,  then  washed  well  first  with  fresh 
water  and  afterwards  with  water  slightly  acidulated  with  acetic  acid  to 
remove  all  trace  of  alkali.*  The  residue  is  air-dried  and  weighed.  As 
the  wool  is  dissolved  by  the  alkali,  the  loss  in  weight  corresponds  to  the 
amount  of  wool,  while  the  residue  represents  the  cotton.  Record  the 
results  as  in  the  following  example: 

Weight  of  sample 5 .  25  grams 

After  boiling  in  caustic  potash 1 .  06  grams 

Loss  equals  wool 4 .  19  grams 

Residue  equals  cotton 1 .  06  grams 

Hence:  Wool  =  79 . 8  per  cent 

Cotton  =  20 . 2  per  cent 

As  the  cotton  present  will  suffer  a  slight  loss  in  the  process,  it  is  customary 
to  add  5  per  cent  of  its  weight  to  the  cotton,  and  to  subtract  this  amount 
from  that  of  the  wool.     With  this  correction  the  above  figures  become: 


Wool  =  78.79  per  cent 
Cotton  =  2 1.21  per  cent 


2.  Analysisof  Fabric  Containing  Silk  and  Cotton.— (a)  Nickel  Hydrate 
Method.  A  weighed  portion  of  the  fabric  (about  5  grams)  is  steeped  for 
five  minutes  in  a  cold  solution  of  nickel  hydrate  in  ammonia ;  then  heated 
almost  to  boiling  for  five  minutes.  This  treatment  should  dissolve  the  silk 
completely.  The  residue  of  cotton  is  thoroughly  washed,  dried,  and 
weighed.  The  nickel  hydrate  solution  for  this  test  is  prepared  as  follows: 
25  grams  of  crystallized  nickel  sulphate  are  dissolved  in  500  cc.  of  water, 
then  sufficient  caustic  soda  solution  is  added  to  precipitate  completely 

*  Another  method  for  the  estimation  of  wool  in  a  union  fabric  is  to  determine  the 
amount  of  nitrogen  present  by  the  Kjeldahl  method.  The  average  amount  of  nitrogen 
in  the  wool  is  taken  as  14  per  cent.  Before  determining  the  nitrogen,  the  material,  of 
course,  must  first  be  freed  from  grease  and  finishing  materials. 

687 


688 


ANALYSIS   OF   TEXTILE    FABRICS 


the  nickel  as  hydrate.  This  precipitate  is  well  washed  with  water  by 
settling  and  decantation,  and  finally  rinsed  into  a  250-cc.  flask  with  125  cc. 
of  water.  The  flask  is  next  filled  with  ammonia  water  and  well  shaken, 
and  the  nickel  hydrate  should  finally  completely  dissolve. 

(6)  Zinc  Chloride  Method. — A  weighed  portion  of  the  sample  is  boiled 
for  two  minutes  in  a  solution  of  basic  zinc  chloride  of  1.72  sp.  gr.  The 
residue  of  cotton  is  thorouglily  washed  first  with  dilute  hydrochloric  acid, 
and  then  with  water,  and  then  dried  and  weighed.  This  treatment  dis- 
solves the  silk  wdthout  materially  affecting  the  cotton.  The  basic  zinc 
chloride  solution  is  prepared  as  follows:  100  grams  of  zinc  chloride  and  4 
grams  of  zinc  oxide  are  dissolved  in  85  cc.  of  hot  water;  after  complete 
solution  the  liquid  should  have  a  density  of  1.72.  This  method  of  analysis 
is  well  adapted  for  plushes  and  other  hea\y  silk  fabrics. 


Fig.  300. — New  Style  Double-cutter  Woolen  vShear  with  Plain  or  List  Saving  Rests 

(Curtis  &  Marble.) 


3.  Analysis  of  Fabric  Containing  Wool  and  Silk. — A  weighed  portion 
of  the  sample  is  steeped  for  two  minutes  in  concentrated  h3^drochloric  aci.l 
at  120°  F.  This  will  dissolve  the  silk  without  materially  affecting  the  wool. 
Wash  the  residue  of  wool,  dry,  and  reweigh. 

4.  Analysis  of  Fabric  Containing  Wool,  Silk,  and  Cotton. — A  weighed 
portion  of  the  sample  is  treated  for  ten  minutes  with  a  cold  solution  of 
nickel  hydrate  in  ammonia  (see  above).  This  will  dissolve  any  silk  present. 
Wash  well,  drj^,  and  reweigh.  The  loss  in  weight  represents  silk.  The 
residue  is  next  boiled  for  ten  minutes  in  a  5  per  cent  solution  of  caustic 
potash.  This  will  dissolve  any  wool  present.  Wash  well,  dry,  and 
reweigh.  The  loss  in  Aveight  represents  wool,  while  the  re.=idue  consists 
of  cotton  (see  above  for  correction  to  apply  to  weight  of  cotton) . 

5.  Distinction  between  True  Silk  and  Artificial  Silk. — Artificial  silk 
(or  lustra-ccUulosc)  is  a  fiber  prepared  from  a  solution  of  collodion  or  other 


DISTINCTION    BETWEEN    VARIOUS   FIBERS  689 

cellulose  solution.  It  consists  of  cellulose,  whereas  true  silk  is  a  nitro- 
genous animal  substance.  Artificial  silk  burns  readily  in  the  air  like  cot- 
ton, without  evolving  a  strong  odor;  while  silk  burns  slowly,  and  emits  a 
characteristic  odor.  To  estimate  the  amount  of  artificial  silk  present  in  a 
mixed  fabric,  a  weighed  portion  of  the  sample  is  treated  at  the  ordinary 
temperature  for  twenty  minutes  with  an  alkaline  solution  of  copper  sul- 
phate. This  will  completely  dissolve  the  natural  silk,  leaving  the  artificial 
fiber  as  a  residue.  The  latter  is  thoroughly  washed,  dried  and  reweighed. 
The  alkaline  solution  of  copper  sulphate  is  prepared  by  dissolving  10  grams 
of  copper  sulphate  in  100  cc.  of  water  and  5  cc.  of  glycerin;  a  strong 
solution  of  caustic  soda  is  then  added  until  the  precipitate  at  first  formed 
just  redissolves. 

6.  To  Distinguish  between  Cotton  and  Linen. —  (a)  Steep  the  sample 
containing  these  two  fibers  for  two  minutes  in  concentrated  sulphuric  acid; 
wash  well  with  water,  gently  rub  with  the  fingers,  and  finally  steep  in  dilute 
ammonia;  then  squeeze  and  dry.  The  cotton  fibers  will  be  converted  into 
a  jelly-like  mass  by  the  action  of  the  acid,  and  is  more  or  less  completely 
removed  by  the  rubbing  and  washing.  The  linen  remains  but  little  altered. 
By  weighing  the  sample  before  and  after  the  treatment  an  approximate  idea 
of  the  amounts  of  cotton  and  linen  present  may  be  obtained,  (h)  Steep 
the  sample  to  be  tested  in  ohve  oil;  then  press  between  filter  paper  to 
remove  the  excess  of  oil.  The  linen  fibers  will  become  gelatinous  in  appear- 
ance and  translucent,  whereas  the  cotton  remains  unaltered.  When 
placed  on  a  dark  background  the  linen  fibers  will  now  appear  dark  and  the 
cotton  fibers  light,  (c)  Steep  the  sample  to  be  tested  in  an  alcoholic  solu- 
tion of  rosolic  acid,  and  then  in  a  strong  solution  of  caustic  soda;  finally 
rinse  in  water.  The  linen  fibers  will  become  rose-colored  while  the  cotton 
is  colored  much  lighter  and  most  of  the  color  is  removed  by  the  rinsing. 
None  of  these  tests  is  very  satisfactory  when  the  linen  has  been  bleached 
for  then  its  cellulose  is  practically  identical  with  that  of  cotton.  The  most 
satisfactory  means  of  qualitatively  distinguishing  linen  from  cotton  is  by  a 
microscopic  examination,  as  these  fibers  exhibit  very  different  microscopic 
properties  (see  the  author's  Textile  Fibers). 

7.  To  Distinguish  between  True  Silk  and  Tussah  Silk.— Tussah  silk 
(and  the  wild  silks  in  general)  may  be  distinguished  from  true  silk  by  the 
following  reactions: 

(a)  Tussah  silk  is  only  partially  dissolved  by  cold  concentrated  hydro- 
chloric acid  (sp.  gr.  1.16),  even  on  standing  for  forty-eight  hours;  whereas 
true  silk  dissolves  almost  instantly. 

(h)  Tussah  silk  requires  a  comparatively  long  time  to  dissolve  in  the 
solution  of  basic  zinc  chloride,  mentioned  on  page  688,  whereas  true  silk 
dissolves  quite  readily. 

(c)  True  silk   dissolves   completely  in   a  semi-saturated   solution   of 


690 


ANALYSIS  OF  TEXTILE   FABRICS 


chromic  acid  when  boiled  for  one  minute;  whereas  tiissah  silk  remains 
unaltered  after  boiling  for  two  to  three  minutes  in  this  solution, 

(d)  To  estimate  the  amount  of  tussah  silk  in  a  fabric,  weigh  off  a  por- 
tion of  the  sample  and  steep  for  ten  minutes  in  cold  concentrated  hydro- 
chloric acid;  wash  the  residue  thoroughly,  dry,  and  reweigh.  The  loss  in 
weight  represents  the  true  silk  while  the  residue  consists  of  tussah  silk. 

8.  To  Test  if  Cotton  Has  Been  Mercerized. — By  the  use  of  Lange's 
iodine  and  zinc  chloride  test  it  is  possible  to  tell  if  cotton  has  been  mer- 
cerized or  not.  The  test  is  carried  out  as  follows:  two  solutions  are  pre- 
pared (1)  5  grams  of  potassium  iodide,  20  cc.  of  water  and  2  grams  of  iodine; 
(2)  25  grams  of  zinc  chloride  and  12  cc.  of  water.  Take  a  piece  of  mer- 
cerized cotton  cloth  or  yarn  and  also  a  piece  of  unmercerized  for  comparison ; 
scour  with  soap  in  order  to  remove  any  finishing  materials,  then  wash. 


aiKSi 


*^<^*-    -VfM-JI  iS'.WSCi»^J»H«#-"=" 


Fig.  301. — Knitgoods  Napper  for  Eiderdowns,  Fleecings,  Robes,  etc.     (Curtis  &  IVIarble.) 


Solution  (2)  is  stirred  into  solution  (1)  until  iodine  begins  to  separate; 
allow  to  settle  and  decant  the  dark  clear  brown  solution.  Steep  the  two 
samples  of  cotton  in  this  liquid  for  three  minutes,  and  then  wash.  The 
unmercerized  cotton  will  very  quickly  lose  its  color,  while  the  mercerized 
cotton  will  remain  blue  for  some  time.  The  test  may  even  be  used  with 
cotton  dyed  in  pale  or  medium  shades;  cotton  that  is  dyed  in  dark  shades 
should  first  be  bleached.     (See  H.  Lange,  Fdrber-ZeiL,  1903,  page  365.) 

9.  To  Test  if  Silk  Has  Been  Weighted  with  Tin  Salts. — A  simple  test 
for  this  purpose  is  to  boil  a  sample  of  the  silk  with  a  dilute  solution  of 
Alizarine  Orange  paste;  if  the  silk  is  tin  weighted  the  fiber  will  become 
colored  a  bright  orange,  whereas  unweighted  silk  will  only  be  stained  a 
dull  bluish  pink.  Another  test  is  to  boil  the  silk  sample  with  a  dilute 
solution  of  Logwood  extract  and  acetic  acid.  If  the  silk  is  tin  weighted  the 
fiber  will  become  dyed  a  violet  color,  whereas  unweighted  silk  will  be 
stained  red.     Of  course  these  tests  can  only  be  applied  to  white  or  light- 


TESTING   FOR  CONDITIONED   WEIGHT  691 

colored  silks  whore  the  original  color  of  the  fiber  will  not  overcome  the  color 
obtained  in  the  test. 

10.  Estimation  of  Sizing  and  Dressing  Materials  in  a  Fabric. — These 
materials  include  sizing,  such  as  starch,  clay,  etc.,  used  for  stiffening  a 
warp  or  fabric;  finishing  materials,  such  as  glue,  magnesium  chloride,  etc., 
which  may  be  added  to  give  a  certain  finish  to  the  cloth;  mordants  and 
dyestuffs,  as  well  as  grease,  etc.,  which  may  be  present  in  the  fabric.  A 
weighed  sample  of  the  fabric  is  boiled  for  fifteen  minutes  in  a  3  per  cent 
solution  of  hydrochloric  acid;  wash  well,  and  boil  for  ten  minutes  in  a  1 
per  cent  solution  of  soda  ash;  wash  well  again,  and  dry.  Re  weigh,  and 
the  loss  will  represent  the  amount  of  size  and  dressing  materials. 

11.  Conditioning  of  Textile  Materials. — By  "  conditioning  "  is  meant 
the  estimation  of  the  amount  of  moisture  present  in  a  yarn  or  faliric  and 
the  subsequent  calculation  of  the  amount  of  normally  dry  fiber  present  in 
the  sample.  The  test  is  usually  carried  out  by  means  of  a  specially  con- 
structed conditioning  oven  wherein  the  weighed  sample  is  heated  at  about 
220°  F.  until  the  moisture  is  completely  driven  out.  The  residue  consists 
of  "  bone-dry  "  fiber,  and  the  loss  is  moisture.  To  the  weight  of  the  dry 
residue  is  then  added  the  amount  of  moisture  corresponding  to  that  nor- 
mally present  in  the  fiber  under  examination.  This  amoimt  is  termed  the 
"  regain,"  and  though  the  standard  varies  in  different  localities,  for  Amer- 
ica it  may  be  taken  as  follows: 

For  materials  of  wool 18    per  cent 

For  materials  of  cotton 9,h  per  cent 

For  silk 11     per  cent 

Where  a  special  conditioning  oven  is  not  available  the  moisture  test  may 
be  made  on  a  small  sample  contained  in  a  weighing  bottle  by  heating  in  an 
ordinary  drying  oven.  The  test  is  much  more  accurate,  however,  when  a 
relatively  large  amount  of  material  is  used. 

Place  100  grams  of  woolen  yarn  in  the  conditioning  oven  and  heat  at 
220°  F.  until  no  further  loss  in  weight  occurs.  This  will  usually  require 
three  to  four  hours.  Note  the  loss  in  weight.  For  example,  suppose  this 
loss  to  be  19.6  grams;   then 

Original  weight 100 .       grams 

Loss  as  moisture 19 . 6    grams 

Residue  as  bone-dry  fiber 80 . 4    grams 

Add  regain,  18  per  cent  of  this 1 1 .  47  grams 

Normal  weight 94  .  87  grams 

Hence  the  sample  contained  94.87  per  cent  of  "  conditioned  "  or  normal 
wool. 


692  ANALYSIS   OF  TEXTILE   FABRICS 

Repeat  the  test,  using  samples  of  loose  wool,  worsted  tops,  raw  cotton, 
cotton  yarn,  raw  silk,  etc.,  and  calculate  the  amounts -of  conditioned  fiber 
in  each  case. 

12.  Estimation  of  Oil  and  Grease  in  Fabrics. — For  analytical  purposes, 
these  substances  are  best  extracted  by  means  of  petroleum  .ether  (ligroin) 
in  a  Soxhlet  extraction  apparatus.  A  weighed  quantity  (about  1  gram) 
of  the  fabric  to  be  tested  is  placed  in  the  capsule  of  the  extractor;  polir 
60  cc.  of  petroleum  ether  in  the  tared  flask  of  the  apparatus.  Con- 
nect the  extractor  with  its  condenser  and  heat  on  a  water-bath,  regu- 
lating the  temperature  so  that  the  solvent  siphons  over  about  everj^  five 
minutes.  Continue  the  extraction  for  one  hour;  then  disconr.ect  the 
extractor,  distill  off  the  solvent,  dry  the  flask  in  a  water  oven,  cool,  and 
finally  reweigh.  The  increase  in  weight  of  the  flask  will  represent  the 
amount  of  grease  and  oil  in  the  fabric. 

13.  Detection  of  Mineral  Oil  in  Textile  Fabrics. — This  oil  is  sometimes 
employed  for  the  oiling  of  stock,  and  is  sometimes  difficult  to  remove  by 
simple  scouring,  if  such  oil  is  of  improper  quality.  Extract  about  10  grams 
of  the  sample  with  50  cc.  of  carbon  tetrachloride  in  a  Soxhlet  extractor. 
Distill  off  the  solvent;  mix  the  residue  of  grease  and  oil  with  water.  If 
mineral  oil  is  present  a  fluorescence  will  be  noticed  on  the  surface  of  the 
water. 

14.  Detection  of  Resin  Oil  in  Textile  Fabrics. — A  weighed  portion 
(about  5  grams)  of  the  sample  is  extracted  with  50  cc.  of  ligroin  (as  above). 
To  the  residue  of  grease,  after  evaporation  of  the  solvent,  add  5  cc.  of 
acetic  anhydride;  shake  well  at  a  gentle  heat,  then  allow  to  cool, 
draw  off  the  layer  of  acetic  anhydride  with  a  pipette,  and  add  to  it  a  drop 
of  concentrated  sulphuric  acid.  The  production  of  a  violet  color  (which, 
however,  is  not  permanent)  wall  indicate  the  presence  of  resin  oils.  If  the 
presence  of  rosin  (colophony)  in  a  textile  fabric  is  suspected,  the  former  may 
be  first  converted  into  resin  oils  by  boiling  with  dilute  hjalrochloric  acid; 
after  which  the  test  is  to  be  carried  out  as  given. 

15.  Estimation  of  Mineral  Matter  in  a  Fabric. — A  weighed  portion 
(1  to  2  grams)  of  the  sample  is  clipped  up  and  ignited  in  a  tared  porcelain 
crucil)le  to  a  complete  ash.  The  weight  of  the  latter  represents  the 
amount  of  mineral  matter  in  the  sample. 

16.  Determination  of  the  Nature  of  Sizing  on  a  Fabric. — The  principal 
ingredients  liable  to  be  present  in  the  sizing  on  a  fabric  are  starch,  dextrin, 
gums,  gelatin,  Irish  moss,  sugar,  rosin,  fatty  matters,  and  various  inor- 
ganic substances  such  as  China  clay,  gypsum,  talc,  magnesia,  magnesium 
chloride,  calcium  chloride,  zinc  chloride,  alumina,  etc. 

To  test  for  these  substances  take  a  sample  of  the  fabric  measuring 
about  30  to  40  sq.  in.,  and  boil  for  several  hours  in  about  250  cc.  of  water. 
This  will  dissolve  all  soluble  materials,  including  starch,  dextrin,  gums, 


TESTS  FOR  NATURE  OF  SIZING  693 

gelatin,   Irish   moss,  sugar,  and   the   chlorides  of   magnesium,   calcium, 
and  zinc.     Test  this  aqueous  extract  in  the  following  manner: 

(1)  Starch. — Add  to  a  portion  of  the  solution  a  few  drops  of  iodine 
solution  (in  potassium  iodide) ;  the  formation  of  a  blue  color  indicates  the 
presence  of  starch. 

(2)  Dextrin  and  gums. — If  no  starch  is  present,  concentrate  a  portion 
of  the  extract  by  boiling;  cool,  and  add  three  times  its  volume  of  alcohol. 
Dextrin  or  gums,  if  present,  will  be  precipitated.  These  may  be  filtered 
off  and  identified  by  burning. 

(3)  Gelatin.— To  a  portion  of  the  extract  add  some  tannic  acid  solution, 
which  will  give  a  precipitate  in  the  presence  of  gelatin. 

(4)  Sugar  and  glucose.— These  may  be  detected  by  boiling  a  portion 
of  the  extract  with  a  little  dilute  hydrochloric  acid,  and  adding  a  few  drops 


Fig.  302.— Steam  Finishing  Machine.     (Curtis  &  Marble.) 

of  Fehling's  solution,  when  a  red  precipitate  of  cuprous  oxide  will  be 
formed  in  the  presence  of  a  sugar. 

(5)  Irish  moss  (or  other  lichen  jelly)  may  be  considered  to  be  present 
if  an  organic  substance  is  known  to  exist  in  the  extract,  and  yet  no  evidence 
of  the  foregoing  compounds  is  found. 

(6)  Chlorides  may  be  detected  by  adding  a  few  drops  of  nitric  acid  to 
the  extract,  followed  by  a  few  drops  of  a  solution  of  silver  nitrate;  the 
formation  of  a  white  precipitate  of  silver  chloride  will  show  the  presence  of 
chlorides. 

(7)  Zinc  may  be  detected  by  adding  ammonium  sulphide  to  the  extract ; 
a  white  precipitate  of  zinc  sulphide  will  indicate  the  presence  of  this  metal. 

(8)  Calcium  may  be  detected  by  adding  ammonium  oxalate  solution  to  a 
portion  of  the  extract,  when  a  white  precipitate  of  calcium  oxalate  will  be 
formed  in  the  presence  of  calcium  compounds. 


694  ANALYSIS  OF   TEXTILE   FABRICS 

(9)  Magnesium  may  be  detected  by  adding  a  few  drops  of  ammonia 
water  and  ammonium  chloride  solution  to  a  portion  of  the  extract,  followed 
by  the  addition  of  sodium  phosphate  solution.  The  formation  of  a  white, 
crystalline  precipitate  of  magnesium  ammonium  phosphate  will  indicate 
the  presence  of  magnesium  salts. 

(10)  Sulphates,  which  may  at  tunes  be  present  as  magnesium  sulphate 
(Epsom's  salts),  may  be  detected  by  adding  a  few  drops  of  hydrochloric 
acid  to  a  portion  of  the  extract,  followed  by  the  adtUtion  of  a  few  drops 
of  a  solution  of  barium  chloride.  The  formation  of  a  white  precipitate  of 
barium  sulphate  will  indicate  the  presence  of  sulphates. 

(11)  Resins,  fats,  and  oils  may  be  tested  for  by  the  methods  already 
given  in  the  preceding  expermients. 

(12)  China  day  (aluminium  siUcate),  gypsum  (calcium  sulphate), 
and  talc  (magnesimii  silicate)  are  insoluble,  even  in  strong  acids,  and  may 
be  found  in  the  ash  left  from  the  ignition  of  a  portion  of  the  fabric,  after 
first  boiling  in  water  to  remove  all  soluble  matters.  It  will  hardly  be  neces- 
sars'  here  to  discriminate  between  these  three  substances  themselves,  as 
such  an  analysis  would  be  both  tedious  and  complicated. 

17.  Determination  of  the  Nature  of  Mordants  on  Woolen  Fabrics. — 
To  determine  the  character  of  the  mordant  which  may  be  present  in  a  yarn 
or  fabric,  a  quahtative  analysis  of  the  ash  must  be  made.  For  this  pur- 
pose, take  about  10  grams  of  the  clippings  of  the  sample  and  ignite,  in  small 
portions  at  a  time,  thoroughly  in  a  porcelain  crucible  until  all  the  carbon 
and  volatile  matters  have  been  burned  away.  The  different  mordants 
are  then  tested  for  in  the  f ollo\\ing  manner : 

(1)  Aluminium  compounds. — The  ash  should  be  white,  or  grajdsh. 
Dissolve  a  portion  in  warm  hj^drochloric  acid,  and  neutralize  the  solution 
wdth  a  slight  excess  of  anmionia.  A  wliite  precipitate  of  aluminium  hydrate 
will  incUcate  the  presence  of  aluminium.  This  should  be  confirmed  by 
heating  a  portion  of  the  ash  on  charcoal,  moistening  with  a  drop  of  cobalt 
nitrate  solution ;  a  blue  color  will  be  obtained  if  aluminium  is  present. 

(2)  Tin  compounds. — The  ash  is  also  white  or  grayish.  Dissolve  in 
boiling  hydrochloric  acid,  and  test  a  portion  of  the  solution  with  sul- 
phureted  hj^drogen  gas.  The  formation  of  a  brownish  j^ellow  precipitate 
will  indicate  the  presence  of  tin. 

(3)  Iron  compomids. — The  ash  is  reddish  brown  in  color.  Dissolve  in 
warm  hydrochloric  acid.  To  a  portion  of  the  solution  add  a  drop  of  nitric 
acid  and  a  few  drops  of  a  solution  of  potassium  ferrocyanide  (j'ellow  prus- 
siate).  The  formation  of  a  blue  precipitate  will  indicate  the  presence  of 
iron.  This  may  be  further  confirmed  by  taking  another  portion  of  the 
solution,  adding  a  drop  of  nitric  acid,  and  a  few  drops  of  a  solution  of 
potassium  sulphocyanide.  The  formation  of  a  red  color  indicates  the 
presence  of  iron. 


TESTS   FOR   NATURE   OF   MORDANTS  695 

(4)  Chromium  compounds. — The  ash  is  yellowish  or  brownish  green. 
Add  a  few  crystals  of  potassium  chlorate  and  fuse.  The  resulting  yellowish 
mass  is  dissolved  in  water;  a  few  drops  of  acetic  acid  are  added,  and  also 
a  solution  of  lead  acetate.  A  yellow  precipitate  of  lead  chromate  will 
indicate  the  presence  of  chromium. 

(5)  Copper  compounds. — The  ash  may  be  brownish  or  black.  Dissolve 
in  warm  hydrochloric  acid,  neutralize  with  an  excess  of  ammonia  water, 
when  the  formation  of  a  blue  color  will  indicate  the  presence  of  copper. 

In  some  cases,  several  of  these  metals  may  occur  together  in  the  ash  of 
the  fabric.  In  order  to  conduct  a  systematic  test  for  all  of  them  proceed 
in  the  following  manner : 

Boil  up  the  ash  with  a  little  concentrated  hydrochloric  acid,  and  filter 
from  any  insoluble  residue.  To  the  diluted  filtrate  add  hydrogen  sulphide 
until  no  further  precipitation  occurs.  A  precipitate  will  indicate  the  pres- 
ence of  copper  or  tin  (consisting  of  black  copper  sulphide  or  brown  tin  sul- 
phide). Filter,  wash  the  precipitate,  and  treat  with  warm  ammonium 
sulphide  solution.  This  will  dissolve  any  tin  sulphide  and  leave  the  copper 
sulphide  as  a  residue.  Filter  the  latter,  if  present;  dissolve  the  residue 
in  a  small  quantity  of  strong  nitric  acid;  dilute  with  water  and  add  slight 
excess  of  ammonia,  when  the  formation  of  a  blue  color  will  indicate  the 
presence  of  copper.  Tin,  if  present  in  the  last  filtrate,  may  be  identified 
by  adding  slight  excess  of  hydrochloric  acid  and  boiling  till  all  odor  of 
hydrogen  sulphide  is  gone.  The  solution  would  now  contain  stannous 
chloride;  filter,  and  pour  into  a  hot  solution  of  mercuric  chloride;  a  white 
precipitate  of  mercurous  chloride  will  indicate  the  presence  of  tin.  The 
filtrate  from  the  precipitated  sulphides  of  copper  and  tin  is  boiled  until 
all  odor  of  hydrogen  sulphide  is  removed.  Add  a  few  drops  of  concen- 
trated nitric  acid  and  boil  for  a  few  minutes  longer.  Add  a  slight  excess 
of  ammonia  water  and  boil  again;  this  will  cause  the  precipitation  of  any 
iron,  chromium,  or  aluminium  as  hydrates.  Filter,  and  wash  the  residue. 
Then  boil  up  with  a  solution  of  potassium  hydrate  which  vfill  dissolve  out 
any  aluminium  hydrate.  Filter  from  the  residue  of  iron  and  chromium 
hydrates;  acidify  the  filtrate  with  hydrochloric  acid,  and  then  add  ammo- 
nia in  slight  excess.  The  formation  of  a  colorless,  gelatinous  precipitate 
of  aluminium  hydrate  will  indicate  the  presence  of  aluminium.  The  above 
residue  of  iron  and  chromium  hydrates  is  now  fused  on  a  piece  of  platinum 
foil  with  a  small  quantity  of  sodium  peroxide.  This  will  result  in  the  for- 
mation of  sodium  chromate,  and  the  fused  mass  will  be  yellow  if  chromium 
is  present.  Dissolve  the  fusion  in  water;  filter  off  any  residue  of  iron 
oxide,  acidify  the  filtrate  with  acetic  acid,  and  add  a  few  drops  of  lead 
acetate  solution.  The  formation  of  a  yellow  precipitate  of  lead  chromate 
will  indicate  the  presence  of  chromiimi.  The  residue  of  iron  oxide,  if 
present,  is  dissolved  in  a  little  hot  concentrated  hydrochloric  acid;   dilute 


696  ANALYSIS  OF   TEXTILE   FABRICS 

with  water  and  add  a  few  drops  of  potassium  ferrocyanide  solution.  The 
formation  of  a  bkie  precipitate  indicates  the  presence  of  iron. 

18.  Determination  of  the  Nature  of  Mordants  on  Cotton  Fabrics. — 
The  mordant.-  which  are  hable  to  be  present  on  cotton  fabrics  fall  under 
three  classes : 

(a)  Those  for  basic  dyes,  including  tannin,  antimony,  iron  and 
copper. 

(6)  Those  for  alizarine  dyes,  including  tannin,  aluminium,  iron,  chro- 
mium, and  fatty  acids. 

(c)  Those  for  acid  dyes,  including  tannin,  aluminium,  fatty  acids,  tin, 
and  lead. 

The  first  class  is  the  principal  one,  whereas  the  last  two  classes  rarely 
come  into  observation,  and  then  only  for  a  few  specific  colors.  The  various 
mordants  may  be  detected  as  follows: 

(1)  Tannin. — A  sample  of  the  fabric  is  boiled  in  a  cUlute  solution  of 
soda  ash  for  twenty  minutes;  the  solution  is  then  poured  off  and  almost 
neutrahzed  with  hydrocliloric  acid.  A  few  drops  of  ferric  chloride  solution 
are  next  added,  when  the  formation  of  a  black  color  (due  to  tannate  of 
iron)  will  indicate  the  presence  of  tannin. 

(2)  Antimony. — A  sample  of  the  fabric  is  boiled  for  fifteen  minutes 
with  concentrated  hydrochloric  acid.  The  solution  is  filtered  and  diluted 
with  water.  A  portion  of  the  filtrate  is  then  treated  with  hydrogen  sul- 
phide, when  the  formation  of  a  j-ellow  (or  orange)  precipitate  (of  anti- 
mony sulphide)  will  incUcate  the  presence  of  antunony.  To  confirm  this, 
however,  the  antimony  sulphide  is  filtered  off  and  dissolved  in  a  little  hot 
concentrated  hydrochloric  acid.  Dilute  with  water,  and  add  to  the  solu- 
tion a  piece  of  zinc  on  platinum  foil.  If  a  black  stain  forms  on  the  plat- 
inum, the  presence  of  antimony  is  confirmed. 

(3)  Iron. — A  portion  of  the  hydrochloric  acid  extract  obtained  above 
is  tested  with  a  few  drops  of  potassium  ferrocyanide  solution.  The  forma- 
tion of  a  blue  color  will  indicate  the  presence  of  iron. 

(4)  Copper. — Another  portion  of  the  same  acid  solution  as  above  is 
neutrahzed  with  an  excess  of  ammonia  water.  The  formation  of  a  blue 
color  in  the  liquid  will  indicate  the  presence  of  copper. 

In  case  the  fabric  is  suspected  to  have  been  dyed  with  alizarine  colors 
(Turkej^  Red,  etc.),  tannin  may  be  tested  for  in  the  manner  given  above. 
Aluminium,  iron,  chromium,  and  tin  mordants  may  be  looked  for  according 
to  the  methods  given  above.  Fatty  acids  maj^  be  tested  for  by  first 
boiling  the  sample  vsith  dilute  hydrochloric  acid  fto  decompose  the  fattj- 
acid  compounds  of  the  metaUic  mordants)  and  then  extracting  with  petro- 
leum ether  and  testing  as  given  above. 

When  it  is  suspected  that  the  sample  is  dyed  with  acid  colors  (which 
may  usually  be  told  by  the  color  not  being  at  all  fast  to  soap  and  water), 


TESTING   BLACK   DYES   ON   COTTON  697 

and  it  is  desired  to  identify  the  mordants  used,  those  of  aluminium,  tannin, 
fatty  acid,  and  tin  may  be  detected  as  given  above. 

(5)  Lead. — The  sample  is  boiled  for  twenty  minutes  in  concentrated 
nitric  acid.  Dilute  the  solution,  and  filter.  To  a  portion  of  the  filtrate 
add  a  few  drops  of  a  solution  of  potassium  chromate,  when  the  formation 
of  a  yellow  precipitate  of  lead  chromate  will  indicate  the  presence  of 
lead. 

19.  Analysis  of  Black  Dyed  Cotton. — As  black  is  one  of  the  principal 
colors  dyed  on  cotton,  and  as  there  are  such  a  number  of  diverse  black  dyes 
used  for  this  purpose,  the  analysis  of  such  colors  is  a  test  frequently 
required  of  the  mill  chemist  and  dyer. 

In  the  first  place,  it  is  well  to  consider  the  different  kinds  of  black  which 
may  be  met  with  in  practice  as  dyed  on  cotton.  The  following  summary 
includes  about  all  of  those  appearing  at  the  present  time : 

(1)  Logwood  Black. 

(2)  Direct  Blue  topped  with  Logwood. 

(3)  Direct  Black  topped  with  Logwood. 

(4)  Aniline  Black. 

(5)  Sulphur  Black  topped  with  Aniline  Black. 

(6)  Direct  Black  topped  with  Aniline  Black. 

(7)  Sulphur  Black. 

(8)  Coupled  Black. 

(9)  Direct  Black. 

(10)  Developed  Black. 

(11)  Developed  Black  treated  with  metallic  salts. 

This  list  does  not  follow  the  order  of  the  importance  of  the  colors,  but  is 
thus  arbitrarily  arranged  to  suit  the  convenience  of  the  method  of  analysis 
Logwood  Black  has  not  nearly  the  same  importance  with  reference  to  cot- 
ton dyeing  that  it  formerly  had.     The  make-up  of  the   cotton  will  also 
determine  in  some  measure  the  kind  of  dyestuff  probably  employed. 

For  the  dyeing  of  loose  cotton,  Sulphur  Black  and  Direct  Black  are 
mostly  used;  for  skein  and  warp  yarns  Sulphur  Black,  Developed  Black, 
and  Direct  Black  are  chiefly  employed;  for  manufactured  cotton  materials. 
Aniline  Black,  Sulphur  Black,  and  Direct  Black  are  mostly  to  be  looked 
for.  In  order  to  make  the  analysis  general  in  character,  however,  we  will 
include  in  the  examination  cotton  in  any  of  its  forms,  and  also  include  all 
of  the  different  blacks  mentioned  in  the  above  given  list. 

The  analysis  may  be  carried  out  in  the  following  general  manner: 

1.  A  sample  of  the  dyed  cotton  is  boiled  for  five  minutes  in  a  1  per  cent 
solution  of  sulphuric  acid,  and  then  washed. 

A.  If  the  fiber  by  this  treatment  changes  in  color  to  brown  and  the 
liquid  acquires  an  orange-yellow  color,  the  dyestuff  employed  was 
Logwood. 


698 


AXALYSLS   OF   TEXTILE   FABRICS 


B.  If  the  color  of  the  fiber  becomes  a  dull  blue  while  the  Hquid  acquires 
an  orange-yellow  color,  the  test  shows  that  a  Direct  Blue  dyestufif  has  been 
used  topped  with  logwood. 

C.  If  the  fiber   remains  black  in  color,  but  the  solution  acquires  a 


Fig.  303. — Hj-draulio  Press  with  Steam-heated  Plates  for  Finishing  Satins,  Orleans,  etc 


reddish  brown  color,  there  may  be  one  of  four  possibilities  in  the  dj'eing, 
and  a  further  examination  is  necessary. 

A  fresh  sample  is  boiled  for  five  minutes  in  a  10  per  cent  solution  of 
stannous  chloride  (tin  crystals),  and  the  following  observations  are 
noted. 


TESTING  BLACK  DYES  ON  COTTON  699 

(1)  If  the  color  of  the  fiber  changes  to  a  bluish  black  while  that  of  the 
liquid  becomes  violet,  the  test  indicates  that  a  Direct  Black  dyestuff  has 
been  employed,  topped  with  Logwood  and  an  iron  mordant. 

(2)  If  the  fiber  remains  black  and  the  liquid  is  not  appreciably  colored, 
the  test  indicates  the  use  of  Anihne  Black,  either  alone  or  in  conjunction 
with  Sulphur  Black,  or  Direct  Black. 

To  determine  which  of  these  three  possibilities  is  the  true  one,  a  further 
examination  is  again  required.  A  fresh  sample  of  the  cotton  material 
is  boiled  for  five  minutes  in  a  20  per  cent  solution  of  sodium  sulphide, 
washed  well,  and  dried: 

(a)  If  the  fiber  remains  black  while  the  liquid  acquires  a  pale  brownish 
yellow  color,  the  test  indicates  that  Aniline  Black  alone  has  been  the  dye- 
stuff  employed. 

(6)  If  the  fiber  remains  black,  but  the  liquid  acquires  a  deep  olive-green 
color,  the  test  indicates  that  the  material  has  been  dyed  with  Sulphur 
Black  and  topped  with  Aniline  Black. 

(c)  If  the  fiber  becomes  grayish  in  color  while  the  liquid  acquires  a 
reddish  brown  color,  the  test  indicates  that  a  Direct  Black  has  been  used 
and  topped  with  Aniline  Black. 

Returning  now  to  the  more  extended  consideration  of  the  first  test  in 
which  the  sample  had  been  treated  with  the  solution  of  sulphuric  acid,  we 
have  the  further  possibility: 

D.  If  the  fiber  remains  black  in  color  while  the  liquid  also  remains 
colorless,  or  practically  so,  it  will  be  necessary  to  make  a  further  test 
to  determine  the  dyestuff.  For  this  purpose  a  fresh  sample  of  the  cotton 
material  is  boiled  for  five  minutes  in  a  20  per  cent  solution  of  sodium  sul- 
phide, then  washed  well,  and  dried. 

(1)  If  the  fiber  remains  black  while  the  liquid  becomes  clear  green  or 
olive  in  color,  the  test  indicates  the  use  of  Sulphur  Black  in  the  dyeing. 

(2)  If  the  fiber  remains  black,  but  the  hquid  acquires  a  dull  brown 
color,  the  test  indicates  the  use  of  a  coupled  black;  that  is  to  say,  the  use  of 
a  direct  dye  applied  after  the  manner  of  the  coupling  process. 

(3)  If  the  fiber  changes  to  a  grayish  color  while  the  hquid  acquires 
a  dark  reddish  brown  color,  the  test  indicates  the  use  of  either  a  direct  black, 
or  a  developed  black. 

To  discrimmate  further  between  these  two  possibilities,  a  fresh  sample 
of  the  material  is  boiled  for  five  minutes  in  a  10  per  cent  solution  of  sodium 
carbonate,  and  the  following  observations  are  noted: 

(a)  If  the  fiber  remains  black  while  the  liquid  acquires  a  violet  or  red- 
dish brown  color,  the  use  of  a  direct  black  is  indicated. 

(6)  If  the  fiber  remains  black  and  the  liquid  colorless  or  only  slightly 
colored,  the  use  of  a  developed  black  is  indicated.  To  ascertain  if  this 
color  has  been  after-treated  with  metallic  salts,  a  sample  of  the  dyed 


700  ANALYSIS   OF   TEXTILE   FABRICS 

cotton  should  be  l^urned  to  a  complete  ash,  and  tliis  ash  must  then  be  sub- 
jected to  the  ordinary  methods  of  chemical  analysis  to  determine  the 
presence  or  absence  of  chromimn  or  copper.  If  either  or  both  of  these 
metals  are  found  to  be  present  in  the  ash,  the  dyeing  has  been  after- 
treated  with  the  corresponding  salt,  which  would  be  chrome  or  bluestone^ 
or  both. 


CHAPTER   XXXIII 
USEFUL  DATA  FOR  DYERS  AND  TEXTILE  CHEMISTS 

1.  Hydrometers. — The  strength  of  many  solutions  is  most  conveniently 
measured  by  a  determination  of  the  density.  The  instrument  used  for 
tliis  purpose  is  known  as  a  hydrometer. 

The  Twaddell  Hydrometer. — This  is  an  instrument  for  measuring  the 
density  of  solutions  and  liquids.  Each  Twaddell  degree  (abbreviated  to 
Tw.)  represents  0.005  unit  of  specific  gravity,  and  the  starting-point  for 
liquids  heavier  than  water  is  the  density  of  water,  which  is  1  sp.  gr.  and  is 
made  equal  to  0°  Tw.  Hence  1°  Tw.  would  be  1.005  sp.  gr.;  2°  Tw. 
would  be  1.010  sp.  gr. ;  10°  Tw.  would  be  1.050  sp.  gr.,  etc.  To  convert 
specific  gravity  readings  into  degrees  Twaddell,  and  vice  versa,  the  following 
formulas  may  be  employed : 

Twaddell  degrees  =  (specific  gravity—  1) X200; 

_  specific  gravity  —  1 
0.005        ~ 

Specific  gravity  =  (Tw.  °  X  0 .  005)  + 1 . 

The  Baume  Hydrometer. — This  is  an  instrument  very  similar  to  that  of 
Twaddell,  but  its  method  of  graduation  is  different.  The  degrees  Baume 
(abbreviated  to  Be.)  bear  no  direct  relation  to  actual  specific  gravity,  but 
tliis  hydrometer  is  largely  used  for  technical  work  both  in  Europe  and 
America.  The  graduation  for  liquids  heavier  than  water  is  made  in 
the  following  manner.  The  zero  mark  (as  with  the  Twaddell  instrument) 
is  obtained  by  immersion  in  distilled  water;  the  instrument  is  then  placed 
in  a  solution  containing  15  parts  by  weight  of  common  salt  and  85  parts 
by  weight  of  water,  and  the  point  to  which  the  hydrometer  sinks  is  called 
15.  The  interval  between  this  point  and  the  zero  is  then  divided  into  15 
equal  parts,  and  the  graduation  continued  as  far  as  desirable.  The 
degrees  Baume  represent  greater  density  than  corresponding  degrees  Twad- 
dell. The  table  on  the  next  page  shows  the  equivalence  between  specific 
gravity,  degrees  Twaddell,  and  degrees  Baume. 

A  solution  of  a  certain  density  may  be  diluted  with  water  (density 

701 


702 


USEFUL   DATA   FOR   DYERS   AND  TEXTILE   CHEMLSTS 


1.000)  to  a  solution  of  another  specified  density  in  accordance  with  the 
following  formula : 

Let  V  =  volume  of  strong  solution ; 
V  =  volume  of  water  to  be  added ; 
D  =  density  of  strong  solution  (in  specific  gravity); 
d  =  density  of  diluted  solution  (in  specific  gravity). 


Then 


v=VX 


D-d 
d-1' 


If  the  densities  are  expressed  in  degrees  Twaddell,  the  formula  becomes: 

T-t 


v=VX- 


t    ' 


where  T  =  density  of  strong  solution  in  degrees  Twaddell ; 
t  =  density  of  diluted  solution  in  degrees  Twaddell. 

This  formula,  however,  can  be  used  only  in  cases  where  there  is  no 
contraction  in  volume  of  the  mixed  liquids;  that  is  to  say,  where  the  vol- 
ume of  the  mixture  is  equal  to  the  sum  of  the  volumes  of  the  solutions  used. 
In  the  case  of  sulphuric  acid  and  other  material  where  there  is  a  reaction 
between  the  chemical  and  the  water  added,  there  is  a  change  in  volume 
which  must  be  allowed  for  in  order  to  obtain  the  proper  density. 


COMPARISON  BETWEEN  THE  SPECIF.  '  C.RAVITY  OF  BAUME   AND 

TWADDELL 


Tw. 

B6. 

Sp.  Gr. 

0 

0 

1.000 

1 

0.7 

1.005 

2 

1.4 

1.010 

3 

2  1 

1.015 

4 

2.7 

1.020 

5 

3.4 

1.025 

6 

4.1 

1.030 

7 

4.7 

1.035 

8 

5.4 

1.040 

9 

6.0 

1.045 

10 

6.7 

1.050 

11 

7.4 

1.055 

12 

8.0 

1.060 

13 

8.7 

1.065 

Tw. 


14 
15 
16 
17 

18 
19 
20 
21 
22 
23 
24 
25 
26 
27 


B6. 


9.4 
10.0 
10.6 
11.2 
11.9 
12.4 
13  0 

13  6 

14  2 
14.9 
15.4 
16.0 
16.5 
17  1 


Sp.  Gr 


.070 

.075 

.080 

.085 

.090 

.095 

.100 

.105 

.110 

.115 

1.120 

1.125 

1.130 

1  135 


Tw. 


28 
29 
30 


Be. 


17.7 
18.3 
18.8 


1    ^1 

19.3 

32 

19.8 

33 

20.3 

i   34 

20.9 

35 

21.4 

i   36 

22.0 

37 

22.5 

38 

23.0 

39 

23.5 

40 

24.0 

41 

24.5 

Sp  Gr. 


1  .0 
145 
150 
155 
160 
165 
170 
175 
180 
185 
190 
195 
200 
205 


HYDROMETER  TABLES 


703 


COMPARISON  BETWEEN  THE  SPECIFIC  GRAVITY  OF  BAUME  AND 
TWADDELL— Continued 


Tw. 

B6. 

Sp.  Gr. 

Tw. 

B6. 

Sp.  Gr.  ! 

Tw. 

B6. 

Sp.  Gr. 

42 

25.0 

1.210 

86 

43.4 

1.430 

130 

56.9 

1.650 

43 

25.5 

1.215 

87 

43.8 

1.435 

131  ' 

57.1 

1.655 

44 

26.0 

1.220 

88 

44.1 

1.440 

132 

57.4 

1.660 

45 

26.4 

1.255 

89 

44.4 

1.445 

133 

57.7 

1.665 

46 

26.9 

1.230 

90 

44.8 

1.450 

134 

57.9 

1.670 

47 

27.4 

1.235 

91 

45.1 

1.455 

135 

58.2 

1.675 

48 

27.9 

1.240 

92 

45.4 

1.460 

136 

58.4 

1.680 

49 

28.4 

1.245 

93 

45.8 

1.465 

137 

58.7 

1 .  685 

50 

28.8 

1.250 

94 

46.1 

1.470 

138 

58.9 

1.690 

51 

29.3 

1.255 

95 

46.4 

1.475 

139 

59.2 

1.605 

52 

29.7 

1.260 

96 

46.7 

1.480 

140 

59.5 

1.700 

53 

30.2 

1.265 

97 

47.1 

1.485 

141 

59.7 

1 .  705 

64 

30.6 

1.270 

98 

47.4 

1.490 

142 

60.0 

1.710 

55 

31.1 

1.275 

99 

47 .  S 

1.495 

143 

60.2 

1.715 

56 

31.5 

1.280 

100 

4S.1 

1.500  1 

144 

60.4 

1.720 

57 

32.0 

1.285 

101 

48.4 

1.505 

145 

60.6 

1.725 

58 

.  32.4 

1.290 

102 

48.7 

1.510 

146 

60.9 

1  730 

59 

32.8 

1.295 

103 

49.0 

1.515 

147 

61.1 

1  755 

60 

3:5 . 3 

1.300 

104 

49.4 

1.520 

148 

61.4 

1  740 

61 

33.7 

1.305 

105 

49.7 

1.525 

149 

61.6 

1 .  745 

62 

34.2 

1.310 

106 

50.0 

1.530 

150 

61.8 

1  750 

63 

34.6 

1.315 

107 

50.3 

1.535 

151 

62.3 

1 .  755 

64 

35.0 

1.320 

108 

50.6 

1.540 

152 

62.5 

1.760 

65 

35.4 

1.325 

109 

50.9 

1.545 

153 

62.5 

1 .  765 

66 

35.8 

1.330 

110 

51.2 

1.550 

154 

62.8 

1.770 

67 

36.2 

1.335 

111 

51.5 

1.555 

155 

63.0 

1.775 

68 

36.6 

1.340 

112 

51.8 

1.560 

156 

63.2 

1.780 

69 

37.0 

1.345 

113 

52.1 

1.565 

157 

63.5 

1.785 

70 

37.4 

1.350 

114 

52.4 

1.570 

158 

63.7 

1.790 

71 

37.8 

1.355 

115 

52.7 

1.575 

159 

64.0 

1 .  795 

72 

38.2 

1.360 

116 

53.0 

1.580 

160 

61.2 

1.800 

73 

38.6 

1.365 

117 

53.3 

1.585 

161 

61.4 

1.805 

74 

39.0 

1.370 

118 

53.6 

1.590 

162 

64.6 

1.810 

75 

39.4 

1.375 

119 

53.9 

1.595 

163 

64.8 

1.815 

76 

39.8 

1.380 

120 

54.1 

1.600 

1G4 

65.0 

1 .  820 

77 

40.1 

1.385 

121 

54.4 

9.605 

165 

65.2 

1 .  825 

78 

40.5 

1.399 

122 

54.7 

1.610 

166 

65.5 

1.830 

79 

40.8 

1.395 

123 

55.0 

1.615  1 

167 

65.7 

1 .  835 

80 

41.2 

1.400 

124 

55.2 

1.620 

168 

65.9 

i.sn 

81 

41.6 

1.405 

125 

55.5 

1.625 

169 

66.1 

1.845 

82 

42.0 

1.410 

126 

55.8 

1.630 

170 

66.3 

1.850 

83 

42.3 

1.415  j 

127 

56.0 

1.635 

171 

66.5 

1.855 

84 

42.7 

1.420 

128 

56.3 

1.640 

172 

66.7 

1.860 

85 

43.1 

1.425 

129 

56.6 

1.645 

173 

67.0 

1.865 

2.  Equivalents  of  Common  Use  in  Measuring. — In  all  scientific  and 
accurate  work  the  metric  system  of  weigiits  and  measures  is  universally 


704 


USEFUL  DATA    FOR   DYERS   AND   'rj:XTlLE   CHEMISTS 


employed.  It  is  presumed  that  the  i\\i<l(^r  is  famihar  in  a  general  way 
with  the  method  and  values  of  the  nietiic  system,  but  his  attention  is 
called  at  this  point  to  following  equivalents,  both  of  the  metric  system  and 
the  common  Enghsh  system,  which  will  be  found  useful  and  practical  for 
reference. 

1  liter  (l.)  =1000  cubic  centimeters  (cc). 
1  liter  of  water  weighs  1  kilogram  (kilo.). 
1  cc.  of  water  weighs  1  gram  (gw.). 
1  cubic  foot  of  water  weiglis  62.5  jjounds. 
1  gram  =  1000  milligrams  {nujin.). 
1  kilogram  =  1000  grams  =  2.2  i)ouiids. 
1  pound  (Avoir.)  =453.9  grams. 
1  gallon  (U.  S.)=231  cubic  inches. 
1  gallon  water  =  8.3  pounds. 
1  pint  water  =  1  pound  (approximately). 
1  liter  =  1  quart  (approximately). 
To  convert  feet  to  meters  multiply  by  0.3. 
Meters  to  feet  multiply  by  3.3. 
Cubic  feet  to  gallons  multiply  by  7.5. 
Gallons  to  cubic  feet  multiply  by  0.13. 
Cubic  feet  to  liters  multiply  by  28.33. 
Liters  to  cubic  feet  multiply  by  0.035. 
Inches  to  centimeters  multiply  by  2.5. 
Centimeters  to  inches  multiply  by  0.4. 
Ounces  to  grams  multiply  by  28.35. 
Grams  to  ounces  multiply  by  0.04. 
Grains  to  grams  multiplj'  by  0.065. 
Grams  to  grains  multiply  by  15.43. 
Yards  to  meters  multiply  by  0.9. 
Meters  to  yards  multiply  by  1.1. 
Quarts  to  liters  multiply  by  0.95. 
Liters  to  quarts  multiply  by  1.06. 
Gallons  to  liters  multiply  by  3.78. 
Liters  to  gallons  multiply  by  0.26. 

An  English  (Imperial)  gallon  is  larger  than  the  United  States  gallon;    it  contains 
2'77i  cubic  inches  =  4.54  liters;  it  contains  10  pounds  of  water. 

3.  CONVERSION  TABLES. 


CONVERSION 

OF   KILOGRAMS   INTO   POUNDS. 

Kilos. 

Lbs. 

Kilos. 

Lb.s 

Kilos. 

Lbs. 

Kilos. 

Lbs. 

1 

2i- 

7 

151 

40 

88 

i;)0 

220^ 

2 

4.1      ! 

8 

17| 

50 

1101- 

200 

441 

3 

6.^ 

9 

19} 

60 

132 

300 

661 

4 

81 

10 

221 

70 

'-.1 

400 

882 

5 

11 

20 

4H 

80 

LT. 

500 

1102i 

6 

13^ 

30 

.    66;,^ 

90 

198              600 

1323 

CONVERSION   TABLES 


705 


CONVERSION  OF  POUNDS  INTO  KILOGRAMS 


Lbs. 

Kih.s. 

Lb3. 

Kilos. 

Lbs. 

Kilos. 

Lbs. 

Kilos. 

1 

0.453 

11 

4.984 

21 

9.515 

40 

18.125 

2 

0.906 

12 

5.437 

22 

9.968 

50 

22.656 

3 

1.359 

13 

5.890 

23 

10.421   1 

60 

27.187 

4 

1.812 

14 

6.343 

24 

10.874 

70 

31.719 

5 

2.265 

15 

6.796 

25 

11.327 

80 

36.250 

6 

2.719 

16 

7.249 

26 

11.780 

90 

40.781 

7 

3.172 

17 

7.702 

27 

12.233 

100 

45.302 

8 

3.625 

18 

8.155 

28 

12.686 

200 

90.625 

9 

4.078 

19 

8.608 

29 

13.139 

300 

135.937 

10 

4.531 

20 

9.062 

30 

13.594 

400 

181.250 

C(N VERSION  OF  OUNCES  INTO  GRAMS 


Ounces. 

Grams. 

Ounces. 

Grams. 

Ounces. 

Grams. 

Ounces. 

Grams. 

1 

28.35 

5 

141.75 

9 

255.15 

13 

368.54 

2 

56.70 

6 

170.10 

10 

283.50 

14 

396.89 

3 

85.05 

7 

198.45 

11 

311.84 

15 

425.24 

4 

113.40 

8 

226.80 

12 

340.19 

16 

453.59 

CONVERSION  OF  GRAMS  INTO  OUNCES  AND  GRAINS 


Grams. 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 


Ounces. 


Grains. 


I  i7r 


15 

30. 
46, 
61. 
77. 
92. 
108 
123 
139 
154 
170 
i  185 
i  201 
!  216 
j  231 
j  247 
I  262 
j  278 
293 
309 
324 
340 


Grams. 

Ounces. 

23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 

'  37 
38 

!       39 

i  40 
41 
42 

i       43 

1 

1 

1          j 

,          1 
1          1 
.          I 

Grains. 

355 

370 

386 

401 

417 

432 

10 

25 

41 

56 

72 

87 

102 

118 

133 

149 

164 

180 

195 

210 

226 


Grams. 


44 
45 
46 
47 
48 
49 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
70 
80 
90 
100 


Ounces. 


Grains. 


241 
257 
272 
288 
303 
319 
334 
350 
3()5 
380 
395 
411 
427 


2 

5 

2 

20 

2 

36 

2 

51 

2 

205 

2 

360 

3 

76 

3 

230 

706 


USEFUL   DATA   FOR   DYERS  AND  TEXTILE   CHEMISTS 


4.  Thermometry.     Comparison    of    Centigrade    Thermometer    with 
Fahrenheit. 


Degrees 
Centigiadc. 

Hcgrees 
Fahrenheit 

1 

Degrees 
Centigrade. 

Degrees 
Fahrenheit. 

Degrees 
Centigrade. 

Degrees 
Fahrenheit. 

Degrees 
Centigrade. 

Degrees 
Fahrenheit. 

110 

230 

1 

80 

176 

50 

122 

20 

68 

109 

228.2 

79 

174.2 

49 

120.2 

19 

66.2 

108 

226.4 

78 

172.4 

48 

118.4 

18 

64.4 

107 

224.6 

77 

170.6 

47 

116.6 

17 

62.6 

106 

222.8 

76 

168.8 

46 

114.8 

16 

60.8 

105 

221 

75 

167 

45 

113 

15 

59 

104 

219.2 

74 

165.2 

44 

111.2 

14 

57.2 

103 

217.4 

73 

163.4 

43 

109.4 

13 

55.4 

102 

215.6 

72 

161.6 

42 

107.6 

12 

53.6 

101 

213.8 

71 

159.8 

41 

105.8 

11 

51,8 

100 

212 

70 

158 

40 

104 

10 

50 

99 

210.2 

69 

156.2 

39 

102.2 

9 

48.2 

98 

208.4 

'        68 

154.4 

38 

100.4 

8 

46.4 

97 

206.6 

67 

152.6 

37 

98.6 

7 

44.6 

96 

204.8 

66 

150.8 

36 

96.8 

6 

42.8 

95 

203 

65 

149 

35 

95 

5 

41 

94 

201.2 

1        64 

147.2 

i        34 

93.2 

4 

39.2 

93 

199.4 

1        63 

145.4 

33 

91.4 

3 

37.4 

92 

197.6 

62 

143.6 

32 

89.6 

2 

35.6 

91 

195.8 

61 

141.8 

31 

87.8 

1 

33.8 

9C 

194 

60 

140 

30 

86 

0 

32 

89 

192.2 

59 

138.2 

29 

84.2 

-1 

30.2 

88 

190.4 

58 

136.4 

28 

82.4 

2 

28.4 

87 

188.6 

!        57 

134.6 

27 

80.6 

3 

26.6 

86 

186.8 

56 

132.8 

1        26 

78.8 

4 

24.8 

85 

185 

!■       55 

131 

25 

77 

5 

23 

84 

183.2 

54 

129.2 

24 

75.2 

6 

21.2 

83 

181.4 

53 

127.4 

23 

73.4 

7 

19.4 

82 

179.6 

52 

125.6 

22 

71.6 

8 

17.6 

81 

177.8 

5. 

123.8 

21 

69.8 

9 

15.8 

To  convert  degrees  Centigrade  to  degrees  Fahrenheit: 
(C°X9)-^5  and  add  32  =  F°. 

To  convert  degrees  Fahrenheit  to  degrees  Centigrade: 
(F°-32)X5^9  =  C°. 


5.  Comparison  of  Relative  Strengths  of  Chemicals 

100  parts  by  weight  of  sal  soda  are  equivalent  to  37  parts  of  soda  ash. 

100  parts  of  soda  ash  are  equivalent  to  270  parts  of  sal  soda. 

100  parts  of  cnjstallized  glaiibersalt  are  equivalent  to  44  parts  of  calcined  glaubersalt. 

100  parts  of  calcined  glaubersalt  are  equivalent  to  227  parts  of  crystallized  glaubersalt. 

100  parts  of  alum  are  equivalent  in  dyeing  value  to  60  parts  of  aluminium  sulphate. 

100  parts  of  aluyninium  sulphate  are  equivalent  to  170  parts  of  a'um. 


DENSITIES   OF  SOLUTIONS 


707 


100  parts  of  sulphuric  acid  168°  Tw.  correspond  to  220  parts  hydrochloric  acid  32° 
Tw.,  and  to  400  parts  acetic  acid  9°  Tw. 

100  parts  of  hydrochloric  acid  32°  Tw.  correspond  to  45  parts  of  sulphuric  acid 
168°  Tw.,  and  to  175  parts  of  acetic  acid  9°  Tw. 

100  parts  of  acetic  acid  9°  Tw.  correspond  to  26  parts  of  sulphuric  acid  168°  Tw., 
and  to  57  parts  of  hydrochloric  acid  32°  Tw. 

100  parts  of  crystallized  sodium  sulphide  are  equivalent  to  50  parts  of  concentrated 
sodium  sulphide. 

100  parts  of  concentrated  sodiu7n  sulphide  are  equivalent  to  200  parts  of  the  crystal- 
lized. 

6.  Tables  of  the  Strengths  and  Densities  of  Various  Solutions 
SULPHURIC  ACID 

At  60°  F.  (15°  C.) 


Deg. 
Tw. 

Per  Cent 

Sulphuric 

Acid. 

Deg. 
Tw. 

Per  Cent 

Sulphuric 

Acid. 

Deg. 
Tw. 

Per  Cent 

Sulphuric 

Acid. 

Deg. 
Tw. 

Per  Cent 

Sulphuric 

Acid. 

2 

1.57 

48 

32.28 

94 

56.90 

140 

77.17 

4 

3.03 

50 

33.43 

96 

57.83 

142 

78.04 

6 

4.49 

52 

34.57 

98 

58.74 

144 

78.92 

8 

5.96 

54 

35.71 

100 

59.70 

146 

79.80 

10 

7.37 

56 

36.87 

102 

60.65 

148 

80.68 

12 

8.77 

58 

38.03 

104 

61.59 

150 

81.56 

14 

10.19 

60 

39.19 

106 

62.53 

152 

82.44 

16 

10.90 

62 

40.35 

108 

63.43 

154 

83.32 

18 

12.99 

64 

41.50 

110 

64.26 

156 

84.50 

20 

14.35 

66 

42.66 

112 

65.08 

158 

85.70 

22 

15.71 

68 

43.74 

114 

65.90 

160 

86.90 

24 

17.01 

70 

44.82 

116 

66.71 

162 

88.30 

26 

18.31 

72 

45.88 

118 

67.59 

164 

90.05 

28 

19.61 

74 

46.94 

120 

68.51 

165 

91.00 

30 

20.91 

76 

48.50 

122 

69.43 

166 

92.10 

32 

22.19 

78 

49.06 

124 

70.32 

167 

93.43 

34 

23.47 

80 

50.11 

126 

71.16 

168 

95.60 

36 

24.76 

82 

51.15 

128 

71.99 

168.3* 

97.70 

38 

26.04 

84 

52.15 

130 

72.82 

168.1 

98.70 

40 

27.32 

86 

53.11 

132 

73.64 

168 

99.20 

42 

28.58 

88 

54.07 

134 

74.51 

167.7 

99.95 

44 

29.84 
31.11 

90 
92 

55.03 
55.97 

136 
138 

75.42 
76.30 

46 

*  Sulphuric  acid  of  97.70  per  cent  has  the  highest  density,  while  that  of  the  stronger  acid  is  slightly 
lower. 


708 


USEFUL  DATA   FOR   DYERS   AND   TEXTILE   CHEMISTS 


HYDROCHLORIC  ACID 

At  G0°  F. 


Deg. 
Tw. 

Per  Cent 

Hydrochloric 

Acid. 

Dog. 
Tw. 

Per  Cent 

Hydrochloric 

Acid. 

Deg. 
Tw. 

Per  Cent 

Hydrochloric 

Acid. 

1 

Dog. 
Tw. 

Per  Cent 

Hydrochloric 

Acid. 

1 

1.15 

11 

11.18 

21 

20.97 

31 

30.55 

2 

2.14 

12 

12.19 

22 

21.92 

32 

31.52 

3 

3.12 

13 

13.19 

23 

22.86 

33 

32.49 

4 

4.13 

14 

14.17 

24 

23.82 

34 

33.46 

5 

5.15 

15 

15.16 

25 

24.78 

35 

34.42 

6 

6.15 

16 

16.15 

26 

25.75 

36 

35.39 

7 

7.15 

17 

17.13 

27 

26.70 

37 

36.31 

8 

8.16 

18 

18.11 

28 

27.66 

38 

37.23 

9 

9.16 

19 

19.06 

29 

28.61 

39 

38.16 

10 

10.17 

20 

20.  ni 

33 

29.57 

40 

39.11 

From  this  table  it  will  be  seen  that  the  degree  Twaddell  indicates  approximately  the 
percentage  of  hydrochloric  acid  in  the  solution. 


ACETIC  ACID 

At  60°  F. 


Per  Cent 
Acetic  Acid. 

Dog.  Tw. 

Per  Cent 
Acetic  Acid. 

Deg.  Tw. 

Per  Cent 
Acetic  Acid. 

Deg.  Tw. 

Per  Cent 
Acetic  Acid. 

Deg.  Tw. 

5 

1.3 

30 

8.2 

55 

13.1 

80 

15.0 

10 

2.8 

35 

9.4 

CO 

13.7 

85 

14.8 

15 

4.3 

40 

10.5 

65 

14.3 

90 

14.3 

20 

5.7 

45 

11.4 

70 

14.7 

95 

13.2 

25 

7.0 

50 

12.3 

75 

14.9 

100 

11.1 

The  densities  above  11°  Tw.  correspond  to  two  liquids  of  different  strengths. 
To  determine  if  the  solution  corresponds  to  the  stronger  or  the  weaker  acid,  a  small 
quantity  of  water  is  added,  and  the  density  is  again  measured.  If  the  density  increases 
on  addition  of  water  the  acid  is  the  stronger;  whereas  if  it  diminshes  the  acid  is  the 
weaker. 


DENSITIES   OF  SOLUTIONS 


709 


CAUSTIC  SODA 

At  G0°  F. 


Per  Cent 
Caustic  Soda. 

Deg.  Tw. 

1 

2.4 

2 

4.6 

3 

7.0 

4 

9.2 

5 

11.8 

6 

14.0 

7 

16.2 

8 

18.4 

9 

20.6 

10 

23.0 

11 

25.2 

12 

27.4 

13 

29.6 

14 

31.8 

15 

34.0 

Per  Cint 
Caustic  Soda. 


16 

17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 


Deg.  Tw. 


36.2 
38.4 
40.4 
42.6 
45.0 
47.2 
49.4 
51.6 
53.8 
55.8 
58.0 
60.0 
62.0 
64.2 
66.4 


!      Per  Cent        t-,        rp  Per  Cent 

CaustirSoda  ^'  iCaustic  Soda. 


31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 


68.6 
70.2 
72.6 
74.8 
76.8 
79.0 
81.0 
83.0 
85.2 
87.4 
89.4 
91.5 
93.6 
95.6 
97.6 


46 
47 
48 
49 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 


Deg.  Tw. 


99.8 
101.6 
103.8 
105.8 
108.0 
110.0 
112.0 
114.0 
116.0 
118.2 
120.2 
122.2 
124.4 
126.6 
128.6 


SODA  ASH 

At  60°  F. 


Deg.  Tw. 

Per  Cent 

Sodium 

Carbonate. 

Deg.  Tw. 

Per  Cent 

Sodium 

Carbonate. 

Deg.  Tw. 

Per  Cent 

Sodium 

Carbonate. 

Deg.  Tw. 

Per  Cent 

Sodium 

Carbonate. 

1 

0.47 

9 

4.28 

17 

8.04 

25 

11.76 

2 

0.95 

10 

4.76 

18 

8.51 

26 

12.23 

3 

1.42 

11 

5.23 

19 

8.97 

27 

12.70 

4 

1.90 

12 

5.71 

20 

9.43 

28 

13.16 

5 

2.38 

13 

6.17 

21 

9.90 

29 

13.63 

6 

2.85 

14 

6.64 

22 

10.37 

30 

14.09 

7 

3.33 

3.80 

15 
16 

7.10 
7.57 

23 

24 

10.83 
11.30 

8 

710 


USEFUL  DATA   FOR   DYERS   AND   TEXTILE  CHEMISTS 


GLAUBERSALT 

At  C0°  F. 


Per  Cent 
Glauber- 
salt. 

Sp.  Gr. 

Per  Cent 
Glauber- 
salt. 

Sp.  Gr. 

Per  Cent 

(ilauber- 

salt. 

Sp.  Gr. 

Per  Cent 
Glauber- 
salt. 

Sp.  Gr. 

1 

1.0040 

9 

1.0358 

17 

1.0683 

25 

1.1015 

2 

1.0079 

10 

1.C398 

18 

1.0725 

26 

1 . 1057 

3 

1.0118 

11 

1.0439 

19 

1.0766 

27 

1.1100 

4 

1.0158 

12 

1.0479 

20 

1.0807 

28 

1.1142 

5 

1.0198 

13 

1.0520 

21 

1.0849 

29 

1.1184 

6 

1.0238 

14 

1.0560 

22 

1.0890 

30 

1 . 1226 

7 

1.0278 
1.0318 

15 
16 

1.0601 
1.0642 

23 
24 

1.0931 
1.0973 

8 

! 

The  percentage  of  desiccated  (or  calcined)  glaubersalt,   Na2S04,  may  be  obtained 
by  multiplying  the  above  percentages  of  crystallized  glaubersalt  by  the  factor  0.441. 


COMMON  SALT  (SODIUM   CHLORIDE) 

At  60°  F. 


Per  Cent 
Sodium 
Chloride. 

Sp.  Gr. 

Per  Cent 
Sodium 
Chlorido. 

S.\  Gr. 

Per  Cent 
Sodium 
Chloride. 

Sp.  Gr. 

Per  Cent 
Sodium 
Chloride. 

Sp.  Gr. 

1 

1.00725 

8 

1.05851 

15 

1.11146 

22 

1 . 16755 

2 

1.01450 

9 

1.06593 

16 

1.11938 

23 

1.17580 

3 

1.02174 

10 

1.07335 

17 

1 . 12730 

24 

1 . 18404 

4 

1.02899 

11 

1.08097 

18 

1 . 13523 

25 

1 . 19228 

5 

1.03624 

12 

1.08859 

19 

1.14315 

26 

1.20098 

6 

1.04366 

13 

1.09622 

20 

1.15107 

26.4 

1.20433 

7 

1.05108 

14 

1 . 10384 

21 

1.15931 

TANNIC   ACID 
At  60°  F. 


Per  Cent 
Tannic 
Acid. 

Sp.  Gr. 

Per  Cent 

Tannic 

Acid. 

Sp.  Gr. 

Per  Cent 
Tannic 
Acid. 

Sp.  Gr. 

Per  Cent 
Tannic 
Acid. 

Sp.  Gr. 

1.0 

1.0040 

2.1 

1.0084 

3.2 

1.0128 

4.3 

1.0172 

1.1 

1.0044 

2.2 

1.0088 

3  3 

1.0132 

4.4 

1.0176 

1.2 

1.0048 

2.3 

1.0092 

3.4 

1.0136 

4.5 

I.OISO 

1.3 

1.0052 

2.4 

1.0096 

3.5 

1.0140 

4.6 

1.0184 

1.4 

1.0056 

2.5 

1.0100 

3.6 

1.0144 

4.7 

1.0188 

1.5 

1.0060 

2.6 

1.0104 

3.7 

1.0148 

4.8 

1.0192 

1.6 

1.0064 

2.7 

1.0108 

3.8 

1.0152 

4.9 

1.0196 

1.7 

1.0068 

2.8 

1.0112 

3.9 

1.0156 

5.0 

1.0200 

1  8 

1.0072 
1.0076 
1.0080 

2.9 
3.0 
3.1 

1.0116 
1.0120 
1.0124 

4.0 
4.1 
4.2 

1.0160 
1.0164 
1.0168 

1  9 

2  0 

! 

DENSITIES  OF  SOLUTIONS 


711 


BLEACHING   POWDER   (CHLORIDE  OF  LIME) 

At  60°  F. 


Density. 

Available  Chlorine. 

Specific  Gravity. 

Tw.  Degrees. 

Per  Liter. 

Per  Gallon. 

Grains. 

Ounces. 

Grains. 

1.1155 

23.1 

71.79 

11 

213 

1.1150 

23 

71.50 

11 

193 

1.1105 

22.1 

68.66 

10 

431 

1.1100 

22 

68.00 

10 

385 

1 . lOGO 

21.2 

65.33 

10 

198 

1 . 1050 

21 

64.50 

10 

140 

1 . 1000 

20 

61.17 

9 

346 

1.0950 

19 

58.33 

9 

146 

1.090G 

18 

55.18 

8 

363 

1.0850 

17 

52.27 

8 

159 

1.0800 

16 

48.96 

7 

365 

1.0750 

15 

45.70 

7 

137 

1.0700 

14 

42.31 

6 

337 

1.0650 

13 

48.71 

6 

85 

1.0600 

12 

35.81 

5 

320 

1.0550 

11 

32.68 

5 

101 

1.0500 

10 

29.41 

4 

309 

1.0450 

9 

26.62 

4 

113 

1.0400 

8 

23.75 

3 

351 

1.0350 

7 

20.44 

3 

119 

1.0300 

6 

17.36 

2 

340 

1.0250 

5 

14.47 

2 

137 

1.0200 

4 

11.44 

1 

362 

1.0150 

3 

8.48 

1 

157 

1.0100 

2 

5.58 

391 

1.0050 

1 

2.71 

190 

1.0025 

h 

1.40 

98 

PROPORTIONS   OF    CHLORINE   IN   WEAK    SOLUTIONS   OF 
BLEACHING   POWDER 


Degrees  Tw. 

Effective  Chlorine, 
Grams  per  Liter. 

3 

u 
1 

3 

4 

8.48 
2.05 
2.71 
4.15 

712 


USEFUL    DATA    FOR    DYERS   AND   TEXTILE   CHEMISTS 


7.  Useful  Data  for  Calculations  in  Dyeing. — To  find  the  capacity  of  a 
rectangular  tank:  IMultiply  the  length  by  the  breadth  by  the  depth  (in  feet), 
then  multiply  this  product  by  7.5  (the  number  of  gallons  in  a  cubic  foot). 
The  result  will  be  the  capacity  of  the  tank  in  U.  S.  gallons.  Or,  multiply 
the  length  by  the  breadth  by  the  depth  in  inches,  and  divide  the  result 
by  231  to  obtain  the  capacity  in  gallons. 

To  find  the  capacity  of  a  circular  tank:  Find  the  square  of  half  the 
diameter  (in  feet),  multiply  by  V"  (an  approximation  to  7r  =  3.1416),  then 
multiply  by  the  depth  (in  feet),  and  finally  multiply  by  7.5.  The  result 
will  be  the  capacity  of  the  tank  in  gallons.  A  shorter  approxunation  to 
the  same  result  is  as  follows:  Square  the  diameter,  multiply  by  the  height, 
and  then  by  the  factor  5.9.  Or,  multiply  the  diameter  in  inches  by  itself, 
then  multiply  by  0.7854,  and  then  by  the  depth  in  inches.  Divide  the 
result  by  231  to  obtain  the  capacity  in  gallons. 

To  convert  grams  per  liter  into  ounces  per  gallon:  Since  one  gallon  is 
equivalent  to  3f  liters,  and  1  oz.  is  equal  to  28.3  grams,  multiply  the  num- 
ber of  grams  per  liter  by  3f  and  divide  l)y  28.3.  A  briefer  formula  is  to 
multiply  grams  per  hter  by  the  factor  0.133. 


Grains 

Grams  per 

Per  Gallon. 

Grams 
per  Liter. 

Grams 
per  Gallon. 

Per  Gallon. 

per  Liter. 

Gallon. 

Lbs. 

Ozs. 

Grns. 

Lbs. 

Ozs. 

Grns. 

1 

3.785 

58 

17 

64.35 

2 

112 

2 

7.570 

116 

18 

68.14 

2 

170 

3 

11.355 

174 

19 

71.92 

2 

228 

4 

15.140 

232 

20 

75 .  70 

2 

286 

5 

18.92 

290 

30 

113.55 

3 

429 

6 

22.71 

348 

40 

151.4 

5 

165 

7 

26.50 

.406 

50 

189.2 

6 

278 

8 

30.28 

27 

60 

227 . 1 

7 

421 

9 

34.07 

85 

70 

265.0 

9 

127 

10 

37.85 

143 

80 

302.8 

10 

270 

11 

41.  G3 

201 

90 

340.7 

11 

413 

12 

45.42 

259 

100 

378.5 

13 

119 

13 

49.21 

317 

1         200 

7.57.0 

1 

10 

238 

14 

53 .  00 

375 

!         300 

1135.5 

2 

7 

357 

1.5 

56 .  76 

433 

i         400 

1514.0 

3 

5 

39 

16 

60.56       1 

1 

2 

54 

500 

1892.0 

4 

2 

158 

Example. — A  solution  of  sulphuric  acid  of  1°  Tw.  density  contains  8 
grams  of  the  acid  per  liter.  Reference  to  the  above  table  shows  that  this 
amount  is  equivalent  to  1  oz.  27  grains  per  gallon. 

To  convert  grams  per  kilogram  into  ounces  per  100  pounds:  Multiply 
by  the  factor  1.6. 


CAPACITY   OF  TANKS 


713 


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USEFUL   DATA   FOR   DYERS   AND   TEXTILE   CHEMISTS 


U.  S    GALLONS  IX  ROUND  TANKS 
For  One  Foot  in  Depth 


Diameter 

Cubic     1 

Diameter 

Cubic 

Diameter 

Cubic 

of 

No. 

Feet  and 

of 

No. 

Feet  and 

of 

No. 

Feet  and 

Ta 

nks. 

U.  S. 

Area  in 

Tanks. 

U.S. 

Area  in 

i     Tanks. 

U.  S. 

Area  in 

Gallons. 

Square 

Gallons. 

Square 

Gallons. 

Square. 

Ft. 

In. 

Feet. 

Ft. 

In. 

Feet. 

Ft. 

In. 

Feet. 

5.87 

.785 

5 

8 

188.66 

25.22 

19 

2120.90 

283.53 

i 

6.89 

.922 

5 

9 

194.25 

25.97 

19 

3 

2177.10 

291.04 

2 

8. 

1.069 

5 

10 

199.92 

26.73 

19 

6 

2234. 

298.65 

3 

9.18 

1.227 

5 

11 

205.67 

27.49 

19 

9 

2291.70 

306.35 

4 

10.44 

1.396 

6 

211.51 

28.27 

20 

2350.10 

314.16 

5 

11.79 

1.576 

6 

3 

229.50 

30.68 

20 

'3 

2409 . 20 

322.06 

6 

13.22 

1.767 

6 

6 

248.23 

33.18 

20 

6 

2469 . 10 

330.06 

7 

14.73 

1.969 

6 

9 

267.69 

35.78 

20 

9 

2529 . 60 

338.16 

8 

16.32 

2.182 

7 

287.88 

38.48 

21 

2591. 

346.36 

9 

17.99 

2.405 

7 

3 

308.81 

41.28 

21 

'3 

2653. 

354.66 

10 

19.75 

2.640 

7 

6 

330.48 

44.18 

21 

6 

2715.80 

363.05 

11 

21.58 

2.885 

7 

9 

352.88 

47.17 

21 

9 

2779.30 

371.54 

23.50 

3.142 

8 

376.01 

50.27 

22 

2843.60 

380.13 

2 

1 

25.50 

3.409 

8 

3 

399.88 

53.46 

22 

'3 

2908 . 60 

388.82 

2 

2 

27.58 

3.687 

8 

6 

424.48 

56. 75 

22 

6 

2974 . 30 

397.61 

2 

3 

29.74 

3.976 

8 

9 

449 . 82 

60.13 

22 

9 

3040.80 

406.49 

2 

4 

31.99 

4.276 

9 

475.89 

63.62 

23 

3108. 

415.48 

2 

5 

34.31 

4.587 

9 

3 

502 . 70 

67.20 

23 

'3 

3175.90 

424.56 

2 

6 

36.72 

4.909 

9 

6 

530.24 

70.88 

23 

6 

3244.60 

433.74 

2 

7 

39.21 

5.241 

9 

9 

558.51 

74.66 

23 

9 

3314. 

443.01 

2 

8 

41.78 

5 .  585 

10 

587.52 

78.54 

24 

3384.10 

452.39 

2 

9 

44.43 

5.940 

10 

3 

617.26 

82.52 

24 

3 

3455. 

461.86 

2 

10 

47.16 

6.305 

10 

6 

640.74 

86.59 

24 

6 

3526.60 

471.44 

2 

11 

49.98 

6.681 

10 

9 

678.95 

90.76 

24 

9 

3598.90 

481.11 

3 

52.88 

7.069 

11 

710.90 

95.03 

25 

3672. 

490.87 

3 

1 

55 .  86 

7.467 

11 

3 

743.58 

99.40 

25 

■3 

3745.80 

500.74 

3 

2 

58.92 

7.876 

11 

6 

776.99 

103.87 

25 

6 

3820.30 

510.71 

3 

3 

62.06 

8.296 

11 

9 

811.14 

108.43 

25 

9 

3895.60 

520.77 

3 

4 

65.28 

8.727 

12 

846.03 

113.10 

26 

3971.60 

530.93 

3 

5 

68.58 

9.168  ' 

12 

'3 

881.65 

117.86 

26 

'3 

4048.40 

541.19 

3 

6 

71.97 

9.621   1 

12 

6 

918. 

122.72 

26 

6 

4125.90 

551 . 55 

3 

7 

75.44 

10.085 

12 

9 

955.09 

127.68 

26 

9 

4204.10 

562. 

3 

s 

78.99 

10.559  ! 

13 

992.91 

132.73 

27 

4283. 

572.66 

3 

9 

82.62 

11.045 

13 

3 

1031.50 

137.89 

27 

■3 

4362.70 

583.21 

3 

10 

86.33 

11.541 

13 

6 

1070.80 

143.14 

27 

6 

4443.10 

593.96 

3 

11 

90.13 

12.048 

13 

9 

1110.80 

148.49 

27 

9 

4524 . 30 

604  81 

4 

94. 

12.566  1 

14 

1151.50 

153.94 

28 

4606.20 

615.75 

4 

1 

97.96 

13.095 

14 

'3 

1193. 

159.48 

28 

"3 

4688.80 

626.80 

4 

2 

102. 

13.635  ! 

14 

6 

1235.30 

165.13 

28 

6 

4772.10 

637.94 

4 

3 

106.12 

14.186 

14 

9 

1278.20 

170.87 

28 

9 

4856.20 

649.18 

4 

4 

110.32 

14.748 

15 

1321.90 

176.71 

29 

4941. 

660.52 

4 

5 

114.61 

15.321 

15 

'3 

1366.40 

182.65 

29 

'3 

5026.60 

671.96 

4 

6 

118.97 

15.90 

15 

6 

1411.50 

188.69 

29 

6 

5112.90 

683.49 

4 

7 

123.42 

16.50 

15 

9 

1457.40 

194.83 

29 

9 

5199.90 

695.13 

4 

8 

127.95 

17.10 

16 

1504.10 

201.06 

30 

5287.70 

706.86 

4 

9 

132.56 

17.72 

16 

'3 

1551.40 

207.39 

30 

'3 

5376.20 

718.69 

4 

10 

137.25 

18.35 

16 

6 

1599.50 

213.82 

30 

6 

5465.40 

730.62 

4 

11 

142.02 

18.99 

16 

9 

1648.40  * 

220.35 

30 

9 

5555. 40 

742.64 

5 

146.88 

19.63 

17 

1697.90 

226.98 

31 

5646.10 

754.77 

5 

i 

151.82 

20.29 

17 

'3 

1748.20 

233.71 

31 

'3 

5737.50 

766.99 

5 

2 

156.83 

20.97 

17 

6 

1799 . 30 

240.53 

31 

6 

5829 . 70 

779.31 

5 

3 

161.93 

21.65 

17 

9 

1851.10 

247.45 

31 

9 

5922.60 

791.73 

5 

4 

167.12 

22.34 

18 

1903.60 

254.47 

32 

6016.20 

804 . 25 

5 

5 

172.38 

23.04 

18 

'3 

1956.80 

261.59 

32 

'3 

6110.60 

816.86 

5 

6 

177.72 

23.76 

18 

6 

2010.80 

268.80 

32 

6 

6205 . 70 

829 . 58 

5 

7 

183.15 

24.48 

18 

9 

2065 . 50 

276.12 

32 

9 

6301 . 50 

842.39 

31 J  Gallons  equals  1  Barrel. 

To  find  the  capacity  of  tanks  greater  than  the  largest  given  in  the  table,  look  in  the  table  for  a 
tank  of  one-half  of  the  given  size  and  multiply  its  capacity  by  4,  or  one  of  one-third  its  size  and 
multiply  its  capacity  by  9,  etc. 


CALCULATION   OF  DYESTUFF   PERCENTAGES 


715 


8. — Tables  for  Calculations  in  Dyeing. 
PERCENTAGE   OF   DYESTUFF   CORRESPONDING    TO    GRAMS    PER 
KILOS,  AND  POUNDS  PER  100  LBS.  OF  GOODS 


100 


Per 
Cent. 

Per  100 
Kilo. 

Per  100  Lbs. 

Per 
Cent. 

Per  100 
Kilo. 

Per  100  Lbs. 

Per 
Cent. 

Per  100 
Kilo. 

Per  100  Lbs. 

gms. 

lb.  ozs.  grs. 

gms. 

lb.  ozs. 

grs. 

gms. 

lb.  ozs. 

grs. 

0.001 

1 

7 

0.29 

290 

4 

280 

0.65 

650 

10 

175 

0.002 

2 

14 

0.30 

300 

4 

350 

0.66 

660 

10 

245 

0.003 

3 

21 

0.31 

310 

4 

420 

0.67 

670 

10 

315 

0.004 

4 

28 

0.32 

320 

5 

53 

0.68 

680 

10 

385 

0.005 

5 

35 

0.33 

330 

5 

123 

0.69 

690 

11 

18 

0.006 

6 

42 

0.34 

340 

5 

193 

0.70 

700 

11 

88 

0.007 

7 

49 

0.35 

350 

5 

263 

0.71 

710 

11 

158 

0.008 

8 

56 

0.36 

360 

5 

333 

0.72 

720 

11 

228 

0.009 

9 

63 

0.37 

370 

5 

403 

0.73 

730 

11 

298 

0.01 

10 

70 

0.38 

380 

6 

35 

0.74 

'  740 

11 

368 

0.02 

20 

140 

0.39 

390 

6 

105 

0.75 

750 

12 

0.03 

30 

210 

0.40 

400 

6 

175 

0.76 

760 

12 

70 

0.04 

40 

280 

0.41 

410 

6 

245 

0.77 

770 

12 

140 

0.05 

50 

350 

0.42 

420 

6 

315 

0.78 

780 

12 

210 

0.06 

60 

420 

0.43 

430 

6 

385 

0.79 

790 

12 

280 

0.07 

70 

53 

0.44 

440 

7 

18 

0.80 

800 

12 

3.50 

0.08 

80 

123 

0.45 

450 

7 

88 

0.81 

810 

12 

420 

0.09 

90 

193 

0.46 

460 

7 

158 

0.82 

820 

13 

53 

0.10 

100 

263 

0.47 

470 

7 

228 

0.83 

830 

13 

123 

0.11 

110 

333 

0.48 

480 

7 

298 

0.84 

840 

13 

193 

0.12 

120 

403 

0.49 

490 

7 

368 

0.85 

850 

13 

263 

0.13 

130 

2 

35 

0.50 

500 

8 

0.86 

860 

13 

333 

0.14 

140 

2 

106 

0.51 

510 

8 

70 

0.87 

870 

13 

403 

0.15 

150 

2 

176 

0.52 

520 

8 

140 

0.88 

880 

14 

35 

0.16 

160 

2 

246 

0.53 

530 

8 

210 

0.89 

890 

14 

105 

0.17 

170 

2 

316 

0.54 

540 

8 

280 

0.90 

900 

14 

175 

0.18 

ISO 

2 

386 

0.55 

550 

8 

3.50 

0.91 

910 

14 

245 

0.19 

190 

3 

18 

0.56 

560 

8 

420 

0.92 

920 

14 

315 

0.20 

200 

3 

88 

0.57 

570 

9 

63 

0.93 

930 

14 

385 

0.21 

210 

3 

158 

0.58 

580 

9 

123 

0.94 

940 

15 

18 

0.22 

220 

3 

229 

0.59 

590 

9 

193 

0.95 

950 

15 

88 

0.23 

230 

3 

299 

0.60 

600 

9 

263 

0.96 

960 

15 

158 

0.24 

240 

3 

369 

0.61 

610 

9 

333 

0.97 

970 

15 

228 

0.25 

250 

4 

0.62 

620 

9 

403 

0.98 

980 

15 

298 

0.26 

260 

4 

70 

0.63 

630 

10 

35 

0.99 

990 

15 

368 

0.27 

270 

4 

140 

0.64 

640 

10 

105  i 

1 

1  Kilo 

1 

0.28 

280 

1 

4 

210 

1  lb.  =  16  oz.  =7000  grains  =  454  grams.  1  oz.  =437^  grains  =  28.349  grams 

1  gram  =  15.43  grains. 

Exam-ple.—ThevQ  is  required  2.16  per  cent  of  dyestuff  for  100  lbs.  of 
goods.     Reference  to  the  above  table  shows  for  100  lbs.  of  goods. 

2        per  cent  is  32  ozs. 

0 .  16  per  cent  is    2  ozs.  246  grs. 
Hence  2 .  16  per  cent  is  34  ozs.  246  grs. 


716 


USEFUL   DATA   FOR   DYERS   AND   TEXTILE   CHEMISTS 


COMPARISON     OF     DYE-TESTS    WITH    TEST     SKEINS     OF     5     GRAMS 
(77  GRAINS)  AND  PRACTICAL  DYEING  OF  100  LBS.   MATERIAL 

The  standard  solutions  for  the  dye-tests  contain  1  gram  of  dycstuff  dissolved  in  1  liter  of  water. 


For 
5  Grams 
Samples. 


1 

2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 


Equivalent 
Percentage. 


Per  Cent 

0.02 
0.04 
0.06 
0.08 
0.10 
0.12 
0.14 
0.16 
0.18 
0.20 
0.22 
0.24 
0.26 
0.28 
0.30 
0.32 
0.34 
0.36 
0.38 
0.40 
0.42 
0.44 
0.46 
0.48 
0.50 
0.52 
0.54 
0 .  56 
0.58 
0.60 
0.62 
0.64 
0.66 
0.68 
0.70 
0.72 
0.74 
0.76 
0.78 
0.80 
0.82 
0.84 
0.86 
0.88 
0.90 
0.92 
0.94 
0.96 


Equivalent  per 
100  Lbs. 


1 

n 
u 

2 

3 

31 
3^ 
4 
4 

5 
5 

<J2 

6 
6 

6^ 

7 
7 
71 


8| 

9 

0^ 

91 
10 
101 
101 

11 

iH 

lU 

12 

12 

121 

13 

13 

13^ 

14 

14 

14^ 

15 

15 


140 

62 
202 
123 

44 
184 
105 

27 
167 

88 

9 

199 

70 
210 
132 

53 
193 
114 

35 
175 

97 

18 
158 

79 

00 
140 

62 
202 
123 

44 
184 
105 

27 
167 

88 

9 

149 

70 
210 
132 

53 
193 
114 

35 
175 

97 

18 
158 


For 
5  Grams 
Samples. 

Equivalent 
Percentage. 

Equivalent 
100  Lbs 

per 

cc. 

Per  Cent. 

lb.           ozs. 

crs. 

49 

0.98 

15§ 

179 

50 

1.00 

51 

1.02 

140 

52 

1.04 

1              1 

A             2 

62 

53 

1.06 

1              1 

■■■             2 

202 

54 

1.08 

1           1 

123 

55 

1.10 

1           11 

44 

56 

1.12 

1       n 

184 

57 

1.14 

1      2 

105 

58 

1.16 

1      91 

27 

59 

1.18 

1           2h 

167 

60 

1.20 

1           3 

88 

61 

1.22 

1           'Sk 

9 

62 

1.24 

1           3^ 

149 

63 

1.26 

1           4 

70 

64 

1.28 

1           4 

210 

65 

1,30 

1           4§ 

132 

66 

1.32 

1          5 

53 

67 

1.34 

1           5 

193 

68 

1.36 

1           51 

114 

69 

1.38 

1           6 

35 

70 

1.40 

1           6 

175 

71 

1.42 

1           61 

97 

72 

1.44 

1           7 

13 

73 

1.46 

1           7 

158 

74 

1.48 

1           71 
i            '  2 

79 

75 

1.50 

1           8 

76 

1.52 

1          8 

140 

77 

1.54 

1           81 

62 

78 

1.56 

1           81 

202 

79 

1.58 

1           9 

123 

80 

1.60 

1           91 

44 

81 

1.62 

1           91 

184 

82 

1.64 

1         10 

105 

83 

1.66 

1          10^ 

27 

84 

1.68 

1         101 

167 

85 

1.70 

1         11 

88 

86 

1.72 

1       lU 

9 

87 

1.74 

1       lU 

149 

88 

1.76 

1         12 

70 

89 

1.78 

1         12 

210 

90 

1.80 

1          12  J 

132 

91 

1.82 

1         13 

53 

92 

1.84 

1          13 

193 

93 

1.80 

1          13i 

114 

94 

1.88 

1          U 

35 

95 

1.90 

1          14 

175 

96 

1.92 

1          141 

97 

COMPARISON   OF   DYE-TESTS 


717 


COMPARISON 

OF  DYE-TESTS- 

— Continued 

For 
5  Grams 
Samples. 

Equivalent 
Percentage. 

Eq 

uivalent 
100  Lbs 

per 

For 
5  Grams 

Equivalent 
Percentage. 

Eq 

livalent 
100  Lbs 

per 

cc. 

Per  Cent. 

lb. 

ozs. 

grs. 

cc. 

Per  Cent. 

lb. 

ozs. 

grs. 

97 

1.94 

1 

15 

18 

149 

2.98 

2 

15^ 

179 

98 

1.96 

1 

15 

158 

150 

3.00 

3 

99 

1.98 

1 

151 

79 

151 

3.02 

3 

0 

140 

100 

2.00 

2 

152 

3.04 

3 

1 

62 

101 

2.02 

2 

140 

153 

3.06 

3 

1 

2 

202 

102 

2.04 

2 

h 

62 

154 

3.08 

3 

1 

123 

103 

2.06 

2 

1 

2 

202 

155 

3.10 

3 

u 

44 

104 

2.08 

2 

1 

123 

156 

3.12 

3 

H 

184 

105 

2.10 

2 

u 

44 

157 

3.14 

3 

2 

105 

lOG 

2.12 

2 

11 

184 

158 

3.16 

3 

2h 

27 

107 

2.14 

2 

2 

105 

159 

3.18 

3 

2h 

167 

108 

2.16 

2 

2^ 

27 

160 

3.20 

3 

3 

88 

109 

2.18 

2 

2h 

167 

161 

3.22 

3 

3,1 

9 

110 

2.20 

2 

3 

88 

162 

3.24 

3 

3^ 

149 

111 

2.22 

2 

3^- 

9 

163 

3.26 

3 

4 

70 

112 

2.24 

2 

3^ 

149 

164 

3.28 

3 

4 

210 

113 

2.26 

2 

4 

70 

165 

3.30 

3 

^ 

132 

114 

2.28 

2 

4 

210 

166 

3.32 

3 

5 

53 

115 

2.30 

2 

4^ 

132 

167 

3.34 

3 

5 

193 

116 

2.32 

2 

5 

53 

168 

3.36 

3 

5k 

114 

117 

2.34 

2 

5 

193 

169 

3.38 

3 

6 

35 

118 

2.38 

2 

5§ 

114 

170 

3.40 

3 

6 

175 

119 

2.38 

2 

6 

35 

171 

3.42 

3 

6^ 

97 

120 

2.40 

2 

6 

175 

172 

3.44 

3 

7 

18 

121 

2.42 

2 

6^ 

97 

173 

3.46 

3 

7 

158 

122 

2.44 

2 

7 

185 

174 

3.48 

3 

7h 

79 

123 

2.46 

2 

7 

158 

175 

3.50 

3 

8 

124 

2.48 

2 

7i 

'  2 

79 

176 

3.52 

3 

8 

140 

125 

2.50 

2 

8 

177 

3.54 

3 

8^ 

62 

126 

2.52 

2 

8 

140 

178 

3.56 

3 

8^ 

202 

127 

2.54 

2 

8^ 

62 

179 

3.58 

3 

9 

123 

128 

2.56 

2 

81 

202 

180 

3.60 

3 

9i 

44 

129 

2.58 

2 

9 

123 

181 

3.62 

3 

9^ 

184 

133 

2.60 

2 

9^ 

44 

182 

3.64 

3 

10 

105 

131 

2.62 

2 

9.^ 

184 

183 

3.66 

3 

10^ 

27 

132 

2.64 

2 

10 

105 

184 

3.68 

3 

10| 

167 

133 

2.66 

2 

101 

27 

185 

3.70 

3 

11 

88 

134 

2.68 

2 

101 

167 

186 

3.72 

3 

lU 

9 

135 

2.70 

2 

11 

88 

187 

3.74 

3 

IH 

149 

136 

2.72 

2 

lU 

9 

188 

3.76 

3 

12 

70 

137 

2.74 

2 

lU 

149 

189 

3.78 

3 

12 

210 

138 

2.76 

2 

12 

70 

190 

3  80 

3 

12i 

132 

139 

2.78 

2 

12 

210 

191 

3.82 

3 

13 

53 

140 

2.80 

2 

12^ 

132 

192 

3.84 

3 

13 

193 

141 

2.82  . 

2 

13 

53 

193 

3.86 

3 

13^ 

114 

142 

2.84 

2 

13 

193 

194 

3.88 

3 

14 

35 

143 

2.86 

2 

13i 

114 

195 

3.90 

3 

14 

175 

.144 

.2.88. 

2 

14, 

35 

196 

.  3.92 

3 

14^ 

97 

145 

2.90 

2  , 

14 

175 

197 

3.94 

3 

15 

18 

146 

2.92 

2 

14^ 

97 

198 

3.96 

3 

15 

158 

147 

2.94 

2  ■ 

15 

18 

199 

3.98 

3 

15| 

79 

148 

2.96 

2 

15 

158 

200 

4.00 

4 

718 


USEFUL   DATA    FOR   DYERS   AND  TEXTILE  CHEMISTS 


TO  CONVERT  CUBIC  CENTIMETERS  OF  TEST  SOLUTIONS  CONTAIN- 
ING ONE  GRAM  OF  DYESTUFF  DISSOLVED  IN  ONE  LITER  INTO 
CORRESPONDING  PERCENTAGES  FOR  10-GRAM  TEST  SKEINS  AND 
WEIGHTS  OF  DYESTUFF  PER  100  POUNDS  OF  GOODS: 


Cc. 
of 

Per 
Cent. 

Weisht  per 
100  Lbs. 

Cc. 
of 

Per 

Cent. 

Weight  per 
100  Lbs. 

Cc. 
of 
Solu- 
tion. 

Per 

Cent. 

on  10 

Glrams. 

Wei(?ht  per 
100  Lbs. 

Solu- 
tion. 

on  10  - 
Grams. 

Lbs. 

Ozs. 

Grs. 

bOlU-    UU  L\J 

tion.   Grams. 

Lbs. 

Ozs. 

Grs. 

Lbs. 

Ozs. 

Grs. 

1 

0.01 

70 

42 

0.42 

6 

315 

83 

1 

0.83  1 

13 

122 

2 

0.02 

140 

43 

0.43 

6 

385 

84 

0.84 

13 

192 

3 

0.03 

210 

44 

0.44 

7 

17 

85 

0.85 

13 

262 

4 

0.04 

280 

45 

0.45 

7 

87 

86 

0.86 

13 

332 

5 

0.05 

350 

46 

0.46 

7 

157 

87 

0.87 

13 

402 

6 

0.06 

420 

47 

0.47 

1 

7 

227 

88 

0.88 

14 

35 

7 

0.07 

1   52 

48 

0.48 

7 

297 

89 

0.89 

14 

105 

8 

0.08 

1  jl22 

49   0.49 

7 

367 

90 

0.90 

14 

175 

9 

0.09 

1  192 

50   0.50 

8 

0 

91 

0.91 

14 

245 

10 

0.10  1 

1  262 

51 

0.51 

8 

70 

92 

0.92 

14 

315 

11 

0.11 

j  1  1332  1 

52 

0.52 

81 

UO 

93 

0.93 

14 

385 

12 

0.12 

! 

1 

402 

53 

0.53 

8 

210 

94 

0.94 

15 

17 

13 

0.13 

2 

35 

54 

0.54 

8 

280 

95 

0.95 

15 

87 

14 

0.14 

2 

105 

55 

0.55 

8 

350 

96 

0.96 

15 

157 

15 

0.15 

2  175 

56 

0.56 

8 

420 

97 

0.97 

15 

227 

16 

0.16 

2  245 

57 

0.57 

9 

52 

98 

0.98 

15 

297 

17 

0.17 

2 

315 

58 

0.58 

9 

122 

99 

0.99 

15 

367 

18 

0.18 

2 

385 

59 

0.59 

9 

192 

100 

1.00 

0 

0 

19 

0.19 

.3 

17 

60 

0.60 

9 

262 

101 

1.01 

0 

70 

20 

0.20 

3 

87 

61 

0.61 

9 

333 

102 

1.02 

0 

140 

21 

0.21 

3 

157 

62 

0,62 

9 

402 

103 

1.03 

0 

210 

22 

0.22 

3 

227 

63 

0.63 

10 

35 

104 

1.04 

0 

280 

23 

0.23 

3 

297 

64 

0.64 

10 

105 

105 

1.05 

0 

350 

24 

0.24 

3 

367 

65 

0.65 

10 

175 

106 

1.06 

0 

420 

25 

0.25 

4 

0 

66 

0.66 

10 

245 

107 

1.07 

52 

26 

0.26 

4 

70 

67 

0.67 

10 

315 

108 

1.08 

122 

27 

0.27 

4 

140 

68 

0.68 

10 

385 

109 

1.09 

192 

28 

0.28 

4 

210 

69 

0.69 

11 

17 

110 

1.10 

262 

29 

0.29 

4 

280 

70 

0.70 

11 

87 

111 

1.11 

332 

30 

0.30 

4 

350 

71 

0.71 

11 

157 

112 

1.12 

402 

31 

0.31 

4 

420 

72 

0.72 

11 

227 

113 

1.13 

2 

35 

32 

0.32 

5 

52 

73 

0.73 

11 

297 

114 

1.14 

2 

105 

33 

0.33 

5 

122 

74 

0.74 

11 

367 

115 

1.15 

2 

175 

34 

0.34 

5 

192 

75 

0.75 

12 

0 

116 

1.16 

2 

245 

35 

0.35 

5 

262 

76 

0.76 

12 

70 

117 

1.17 

2 

315 

36 

0.36 

5 

332 

77 

0.77 

12 

140 

118 

1,18 

2 

385 

37 

0.37 

5 

402 

78 

0.78 

12 

210 

119 

1.19 

3 

17 

38 

0.38 

6 

35 

79 

0.79 

12 

280 

120 

1.20 

1 

3 

87 

39 

0.39 

6 

105 

80 

0.80 

12 

350 

121 

1.21 

3 

157 

40 

0.40 

6 

175 

81 

0.81 

12 

420 

122 

1.22 

3 

227 

41 

0.41 

6 

245 

82 

0.82 

1 

13 

52 

123 

1.23 

3 

297 

CONVERSION   TABLE   FOR   D\"E-TESTS 


719 


TO  CONVERT  CUBIC  CENTIMETERS 

OF 

TEST   SOL 

UTIO> 

f  S — Contin  ued 

Cc. 

of 

Solu- 

Per 
Cent, 
on  10 
Grams. 

Weight  per 
100  Lbs. 

Cc. 
of 
Solu- 
tion. 

Per 
Cent, 
on  10 
Grams. 

Weicht  per 
100  Lbs. 

Co. 

of 
Solu- 
tion. 

Per 
Cent, 
on  10 
Grams. 

Weight  ppr 
100  Lbs. 

tion. 

Lbs. 

Ozs.    Grs. 

Lbs. 

Ozs. 

Grs. 

Lbs. 

Ozs. 

Grs. 

124 

1.24 

3   367 

150 

1.50 

8 

0 

176 

1.76 

12 

70 

125 

1.25 

4 

0 

151 

1.51 

1 

8 

70 

177 

1.77 

12 

140 

126 

1.26 

4 

70 

152 

1.52 

8 

140 

178 

1.78 

12 

210 

127 

1  27 

4 

140 

153 

1.53 

8 

210 

179 

1.79 

12 

280 

128 

1.28 

4 

210 

154 

1.54 

8    280  1 

180 

1.80 

12 

350 

129 

1.29 

4 

280 

155 

1.55 

8 

350 

181 

1.81 

12 

420 

130 

1.30 

4 

350 

156 

1.56 

8 

420 

182. 

1.82 

13 

52 

131 

1.31 

4 

420 

157 

1.57 

9 

52 

183 

1.83 

1      13      122 

132 

1.32 

5 

52 

158 

1.58 

9 

122 

184 

1.84 

1      13      192 

133 

1  33 

5 

122 

159 

1.59 

9 

192 

185 

1.85 

1      13 

262 

131 

1.34 

5 

192 

160 

1.60 

9 

262 

186 

1.86 

1      13 

332 

135 

1.35 

5 

262 

161 

1.61 

9    332 

187 

1.87 

13 

402 

133 

1.33 

5 

332 

162 

1.62 

1* 

9    402 

188 

1.88 

14 

35 

137 

1.37 

5 

402 

163 

1.63 

10 

35 

189 

1.89 

14 

105 

13S 

1.38 

6 

35 

164 

1.64 

10 

105 

190 

1.90 

1 

14 

175 

139 

1.39 

6 

105 

165 

1.65 

10 

175 

191 

1.91 

1 

14 

245 

140 

1.40 

6 

175 

166 

1.66 

10 

245 

192 

1.92 

14 

315 

141 

1.41 

6 

245 

167 

1.67 

10 

315 

193 

1.93 

1 

14 

385 

142 

1.42 

6 

315 

168 

1.68 

10 

385 

194 

1.94 

15 

17 

143 

1.43 

6 

385 

169 

1.69 

11 

17 

195 

1.95 

15 

87 

144 

1.44 

7 

17 

170 

1.70 

11 

87 

196 

1.96 

15 

157 

145 

1.45 

7 

87 

171 

1.71 

11 

157 

197 

1.97 

15 

227 

146 

1.46 

7 

157 

172 

1.72  '     1 

11 

227 

198 

1.98 

15 

297 

147 

1.47 

7 

227 

173 

1.73        1 

11 

297 

199 

1.99 

15 

367 

148 

1.48 

7 

297 

174 

1.74        1 

11 

367 

200 

2.00 

2 

0 

0 

149 

1.49 

7 

367 

175 

1.75        1 

12 

0 

300 

3.00 

3 

0 

0 

J 

"Hxample. — To  obtain  0.67 

per  cent  of  dyestuff  on  a  10-gram  test  skein 

of  ^\ 

ool  or  cotton,  when  the  s 

olution  contains  1  gram  of  dyestuff  per  liter, 

it  w 

ould  b 

3  nec 

'essa 

ry  tc 

)  take 

67  cc. 

oft 

le  s( 

)lutic 

m;  ar 

id  for 

the  ( 

ij-eii 

igof 

100  lbs.  of  goods  this  would  be  equivalent  to  10  oz.  315  grs.  of  dyestuff. 

In  case  a  5-gram  test  skein  is  used,  the  above  figures  in  the  percentage 
and  weight  columns  are  to  be  multiplied  by  2.  For  instance,  1.34  per  cent 
of  dyestuff  would  be  equivalent  to  67  cc.  of  the  solution,  or  to  1  lb.  5  ozs. 
193  grs.  on  100  lbs.  of  material. 

In  case  the  dj'estuff  solution  contains  more  than  1  gram  per  liter, 
it  will  be  necessary  to  multiply  the  figures  in  the  percentage  and  weight 
columns  by  the  number  of  grams  per  Uter  of  the  solution.  For  instance, 
if  the  solution  contains  5  grams  per  Hter  67  cc.  would  be  equivalent  to 
3.35  per  cent,  or  to  3  lbs.  5  ozs.  262  grs.  on  100  lbs.,  if  a  10-gram  test  skein 
is  used.  If  a  5-gram  test  skein  be  used,  67  cc.  of  such  a  solution  would  be 
equivalent  to  6.70  per  cent,  or  to  6  lbs.  11  ozs.  87  grs.  on  100  lbs.  of  goods. 


720 


USEFUL   DATA   FOR    DYERS   AND   TEXTILE   CHEMLSTS 


TO  CONVERT  PERCENTAGE  OF  COLOR  (ON  100  LBS.  OF  GOODSt 
INTO  QUANTITY  OF  STANDARD  SOLUTION  OF  4  OZS.  OF  DRY 
COLOR  PER   GALLON 


Weight. 

Per  Cent. 

Solution  of  4  Ounces  per  Gallon. 

Lbs. 

Quarts. 

Pints.                      Gills.                    Noggins. 

100 

1*^ 

1 

8 
1 

1 

2 
3 
4 
8 
16 

1                 

1  /:- 

100 

100 

1 

li 

100 

100 

1 

100 

1 

1                                1 

2  noggins  =  1  gill 
4  gills  =  1  pint 


2  pints  =  1  quart 
4  quarts  =  1  gallon 


Convenient  data  regarding  quantities  of  water  based  on  U.  S.  gallon: 

1  gallon  =  231        cubic  inches  =  8.3       lb. 

1  quart  =   57 .  75  cubic  inches  =2.1       lb. 

lpint=  28.88  cubic  inches  =    1.0       lb. 

1  gill=     7.22  cubic  inches  =      .25     lb. 

1  cubic  foot  =    17 .  28  cubic  inches  =  62 . 5      lb.  = ' 


5  gallons 


1  cubic  inch 


=      .036  lb. 


REDUCTION  OF  GRAMS  TO  OUNCES  PER  100  LBS.  GOODS 


Grams. 

Ounces 
for  Solution.     | 

Grams. 

Ounces          ! 
for  Solution. 

Grams. 

Ounces 
for  Solution. 

1 

.35 

11 

3.88 

21 

7  41 

2 

.71 

12 

4.24 

22 

7.76 

3 

1.06 

13 

4.58 

23 

8  12 

4 

1.41 

14 

4.93 

24 

8.47 

5 

1.77 

15 

5.29 

25 

8.82 

6 

2.12 

16 

5.64 

26 

9.17 

7 

2.47 

17 

5.99 

27 

9.53 

8 

2.83 

18 

6.34 

28 

9  88 

9 

3.18 

19 

6.60 

29 

10.22 

10 

3.53 

20 

7.06 

30 

10.59 

To  use  any  number  of  grams  per  100  lbs.  of  goods,  dissolve  the  corre- 
sponding number  of  ounces  in  above  table  in  10  gallons  of  water,  and  use 
1  gallon  of  this  solution  per  100  lbs.  goods. 

For  Example. — To  use  42  grams  of  dyestuff  per  100  lbs.  goods: 

30  grams  =  10 .  59  ozs. 

10  grams  =   3 .  53  ozs. 

2  grams  =      .71  oz. 

42  grams  =  14 .  83  ozs. 

Therefore,  dissolve  14.83  ozs.  of  dyestuff  in  10  gallons  of  water  and  use 

1  gallon  of  the  solution. 


CONVERSION   TABLES 


721 


REDUCTION  OF  GRAMS  PER  KILOGRAM  OF  GOODS  TO  OUNCES  PER 

100  LBS.   OF  GOODS 


Grams 
per  Kilo. 

Ounces 
per  100  Lbs. 

Grams 
per  Kilo. 

Ounces 
per  100  Lbs. 

Grams 
per  Kilo. 

Ounces 
per  100  Lbs. 

1 

1.6 

18 

28.8 

35 

56.0 

2 

3.2 

19 

30.4 

36 

57.6 

3 

4.8 

20 

32.0 

37 

59.2 

4 

6.4 

21 

33.6 

38 

60.8 

5 

8.0 

22 

35.2 

39 

62.4 

6 

9.6 

23 

36.8 

40 

64.0 

7 

11.2 

24 

38.4 

41 

65.6 

8 

12.8 

25 

40.0 

42 

67.2 

9 

14.4 

•   26 

41.6 

43 

68.8 

10 

16.0 

27 

43.2 

44 

70.4 

11 

17.6 

28 

44.8 

45 

72.0 

12 

19.2 

29 

46.4 

46 

73.6 

13 

20.8 

30 

38.0 

47 

75.2 

14 

22.4 

31 

49.6 

48 

76.8 

15 

24.0 

32 

51.2 

49 

78.4 

16 

25.6 

33 

52.8 

50  . 

so.o 

17 

27.2 

34 

54.4 

To  convert  grams  per  kilo  into  ounces  per  100  lbs.  multiply  by  the  factor  1.6. 

REDUCTION    OF    FRACTIONAL    PERCENTAGES    TO    OUNCES    PER    100 

LBS.  OF  GOODS 


Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

1 
2 

8.00 

i 

2.00 

t\ 

7.28 

T% 

11.11 

3 

n 

6.00 

6 
1  1 

8.73 

1  0 

T¥ 

12.31 

1 

5.33 

5 

8 

10.00 

7 
1  1 

10.19 

H 

13.54 

2 

10.66 

7 

5 

14.00 

8 

TT 

9 

1 1 

11.64 
13.09 

1  2 
T3 

14.77 

3 

4 

4.00 
12.00 

1 
9 
2 
9 

1.77 
3.55 

1  0 
H 

14.55 

1 

TT 

3 
1  4 

1.14 
3.44 

1 
5 

* 

f 

4 
"5 

3.20 

6.40 

9.60 

12.80 

4 
9 

f 

7 

8 
9 

7.11 

8.88 

12.44 

14.22 

5 

T^ 

7 

12 
1  1 
T2 

1.34 

6.66 

9.33 

14.66 

5 

TT 

9 

TT 
ii 

14 
1  3 

TT 

5.72 
10.29 
10.57 
14.86 

i 

2.66 

1 
1  0 

1.60 

1 
T5" 

1.07 

5 
6 

13.30 

3 
TO 

4.80 

1 
TS" 

1.23 

2 
15 

2.13 

7 
TO 

11.20 

2 
1  3 

2.46 

tV 

4.27 

1 

T 

2.29 

tV 

14.40 

3 
T¥ 

3.69 

6 

IT 

6.40 

2 
T 

4.58 

4 
1  3 

4.92 

7 
T5^ 

7.47 

* 

6.86 

1 
1  1 

1.45 

T^3 

6.16 

T^ 

8.53 

4 

7 

9.15 

2 
1  1 

2.91 

6 
T3" 

7.39 

1  1 
T5 

11.73 

f 

11.43 

3 

1  1 

4.37 

7 
13 

8.61 

1  3 
15 

13.87 

6 

Y 

13.80 

4 

5.82 

T^ 

9.85 

1  4 
T5^ 

14.96 

722  USEFUL   DATA   FOR   DYERS   AND   TEXTILE   CHEMISTS 


REDUCTION   OF   DECIMAL   PERCENTAGES   TO   OUNCES   PER    100   LBS. 

OF  GOODS 


Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

Per  Cent. 

Ounces 

per  100  Lbs. 

Goods. 

1 

Per   Cent. 

Ounces 

per  100  Lbs. 

Goods. 

.10 

1.60 

.35 

5.60 

.60 

9.60 

.85 

13.60 

.15 

2.40 

.40 

6.40 

.65 

10.40 

.90 

14.40 

.20 

3.20 

.45 

7.20 

.70 

11.20 

.95 

15.20 

.25 

4.00 

.50 

8.00 

.75 

12.00 

1.00 

16.00 

30 

4.80 

1 

.55 

8.80 

.80 

12.80 

1 

REDUCTION  OF  DECIMAL  PARTS  OF  POUNDS  TO  OUNCES 


Lbs. 

Ots. 

Lbs. 

Ozs. 

Lbs. 

Ozs. 

Lbs. 

Ozs. 

.01 

.16 

.14 

2.24 

.27 

4.32 

.40 

6.40 

.02 

.32 

.15 

2.40 

.28 

4.48 

.41 

6.56 

.03 

.48    ■ 

.16 

2.56 

.29 

4.64 

.42 

6.72 

.04 

.64 

.17 

2.72 

.30 

4.80 

.43 

6.88 

.05 

.80 

.18 

2.88 

.31 

4.96 

.44 

7.04 

.06 

.96 

.19 

3.04 

.32 

5.12 

.45 

7.20 

.07 

1.12 

.20 

3.20 

.33 

5.28 

.46 

7.36 

.08 

1.28 

.21 

3.36 

.31 

5.44 

.47 

7.52 

.09 

1.44 

.22 

3.52 

.35 

5.60 

.48 

7.68 

.10 

1.60 

.23 

3.68 

.36 

5.76 

.49 

7.84 

.11 

1.76 

.24 

3.84 

.37 

5.92 

.50 

8.00 

.12 

1.92 

.25 

4.00 

.38 

6.08 

13 

2.08 

.26 

4.16 

1       .39 

6.24 

REDUCTION  OF  DECIMAL  PERCENTAGES  OF  GALLONS  TO  QUARTS 

AND   PINTS 


Gals. 


.05 
.10 
.15 
.20 
.25 
.30 
.35 


Qts. 


Pts. 


Gals 


.40 
.45 
.50 
.55 
.60 
.65 
.70 


Qts. 


Pts. 


Gals. 

Qts. 

Pts. 

.75 

•  3 

.80 

3 

2 

6 

.85 

3 

4 
5 

.90 

3 

H 

.95 

3 

If 

1.00 

^ 

CONVERSION   TABLES 


723 


REDUCTION  OF  LITERS  PER  KILOGRAM  OF  GOODS  TO  GALLONS  PER 

100  LBS.   OF  GOODS 


Liters 
jicr  Kilo. 

Gallons 
per  100  I,bs. 

Liters 
per  Kilo. 

Gallons 
per  100  Lbs. 

Liters 
per  Kilo. 

Gallons      i 
per  100  Lbs.  , 

Liters 
per  Kilo. 

Gallons 
per  100  Lbs. 

1 

11.99 

14 

167.88 

27 

323.78 

40 

479.68 

2 

23.98 

15 

179.88 

28 

335,77 

41 

491.67 

3 

35.97 

16 

191.87 

29 

347.76 

42 

503 . 66 

4 

47.96     i 

17 

203.86 

30 

359 . 76 

43 

515.65 

5 

59.96 

18 

215.85 

31 

371.75 

44 

527.64 

6 

71.95 

19 

227.84 

32 

383.74 

45 

539.64 

7 

83.94 

20 

239.84 

33 

395.73 

46 

551.63 

8 

95.93 

21 

251.83 

34 

407.72 

47 

563.62 

9 

107.92 

22 

263.82 

35 

419.72 

48 

575.61 

10 

119.92 

23 

275.81 

36 

431.71 

49 

587.60 

11 

131.91 

24 

287.80 

37 

443 . 70 

50 

599.60 

12 

143.90 
155.89 

25 
26 

299.80 
311.79 

38 
39 

4.55.69 
467.68 

13 

REDUCTION   OF  GRAMS  PER  LITER  TO  OUNCES  PER  GALLON 


Grams 
per  Liter. 

1 

Ounces 
per  Gallon. 

Grams 
per  [iter. 

Ounces 
Per  Gallon. 

Grams 
per  Liter. 

Ounces 
per  Gallon. 

Grams 
per  Liter. 

Ounces 
per  Gallon. 

1 

.13 

9 

1.20 

17 

2.26 

25 

3.33 

2 

.26 

10 

1.33 

18 

2.40 

26 

3.46 

3 

.40 

11 

1.46 

19 

2.53 

27 

3.60 

4 

.53 

12 

1.60 

20 

2.66 

28 

3.73 

5 

.66 

13 

1.73 

21 

2.80 

29 

3.86 

6 

.80 

14 

1.86 

22 

2.93 

30 

4.00 

7 

.93 
1.06 

15 
16 

2.00 
2.13 

23 
24 

3.06 
3.20 

8 

To  convert  grams  per  liter  into  ounce.?  per  gallon,  multiply  by  the  factor  0.133. 


724  USEFUL   DATA   FOR   DYERS   AND   TEXTILE  CHEMISTS 

PERCENTAGE  TABLES 


Per  Cent. 

For  10  Lbs. 

For  .50  Lbs. 

For  100  Lbs. 

10.0 
9.0 

8.0 
7.0 

lib. 

14  oz.  175  grains 
12  oz.  350  grains 
11  oz.    87  grains 

5    lbs. 
4|  lbs. 
4    lbs. 
3^  lbs. 

10  lbs. 
9  lbs. 
8  lbs. 
7  lbs. 

6.0 

9  oz.  263  grains 

3    lbs. 

6  lbs. 

5.0 
4.0 
3.0 
2.0 

8oz. 

6  oz.  175  grains 
4  oz.  350  grains 
3  oz.    88  grains 

2\  lbs. 
2    lbs. 
Ulbs. 
1    lb. 

5  lbs. 
4  lbs. 
3  lbs. 
2  lbs. 

1.0 

1  oz.  263  grains 

8oz. 

1  lb. 

0.99 
0.98 
0.97 
0.96 

1  oz.  256  grains 
1  oz.  249  grains 
1  oz.  242  grains 
1  oz.  235  grains 

7  oz.  403  grains 
7  oz.  368  grains 
7  oz.  333  grains 
7  oz.  298  grains 

15  oz.  368  grains 
15  oz.  298  grains 
15  oz.  228  grains 
15  oz.  158  grains 

0.95 

1  oz.  228  grains 

7  oz.  2c3  grains 

15  oz.    88  grains 

0.94 
0.93 
0.92 
0.91 

1  oz.  221  grains 
1  oz.  214  grains 
1  oz.  207  grains 
1  oz.  200  grains 

7  oz.  228  grains 
7  oz.  193  grains 
7  oz.  158  grains 
7  oz.  123  grains 

15  oz.     18  grains 
14  oz.  385  grains 
14  oz.  315  grains 
14  oz.  245  grains 

0.90 

1  oz.  193  grains 

7  oz.    88  grains 

14  oz.  175  grains 

0.89 

0.88 
0.87 
0.86 

1  oz.  186  grains 
1  oz.  179  grains 
1  oz.  172  grains 
1  oz.  165  grains 

7  oz.    53  grains 
7  oz.     18  grains 
6  oz.  420  grains 
G  oz.  385  grains 

14  oz.  105  grains 
14  oz.     35  grains 
13  oz.  403  grains 
13  oz.  333  grains 

0.85 

1  oz.  158  grains 

6  oz.  350  grains 

13  oz.  263  grains 

0.84 
0.83 
0.82 
0.81 

1  oz.  151  grains 
1  oz.  144  grains 
1  oz.  137  grains 
1  oz.  130  grains 

6  oz.  315  grains 
6  oz.  280  grains 
6  oz.  245  grains 
6  oz.  210  grains 

13  oz.  193  grains 
13  oz.  123  grains 
13  oz.    53  grains 
12  oz.  420  grains 

0.80 

1  oz.  123  grains 

6  oz.  175  grains 

12  oz.  3.50  grains 

0.79 
0.78 
0.77 
0.76 

1  oz.  116  grains 
1  oz.  109  grains 
1  oz.  102  grains 
1  oz.    95  grains 

6  oz.  140  grains 
6  oz.  105  grains 
6  oz.    70  grains 
6  oz.    35  grains 

12  oz.  280  grains 
12  oz.  210  grains 
12  oz.  140  grains 
12  oz.    70  grains 

PERCENTAGE  TABLES  FOR  DYEING 


725 


PERCENTAGE  TABLES— Continued 

Per  Cent. 

For  10  Lbs. 

For  50  Lbs. 

For  100  Lbs. 

0.75 

1  OZ.    88  grains 

6  oz. 

12  OZ. 

0.74 

0.73 
0.72 
0.71 

1  oz.    81  grains 
1  oz.    74  grains 
1  oz.    67  grains 
1  oz.    60  grains 

5  oz.  403  grains 
5  oz.  368  grains 
5  oz.  333  grains 
5  oz.  298  grains 

11  oz.  368  grains 
11  oz.  298  grains 
11  oz.  228  grains 
11  oz.  158  grains 

0.70 

1  oz.    53  grains 

5  oz.  263  grains 

11  oz.    88  grains 

0.69 
0.68 
0.67 
0.66 

1  oz.    46  grains 
1  oz.    39  grains 
1  oz.    32  grains 
1  oz.    25  grains 

5  oz.  228  grains 
5  oz.  193  grains 
5  oz.  158  grains 
5  oz.  123  grains 

11  oz.    18  grains 
10  oz.  385  grains 
10  oz.  315  grains 
10  oz.  245  grains 

0.65 

1  oz.    18  grains 

5  oz.    88  grains 

10  oz.  175  grains 

0.64 
0.63 
0.62 
0.61 

1  oz.     11  grains 

1  oz.      4  grains 

434  grains 

427  grains 

5  oz.    53  grains 
5  oz.    18  grains 
4  oz.  420  grains 
4  oz.  385  grains 

10  oz.  105  grains 

10  oz.  135  grains 

9  oz.  403  grains 

9  oz.  333  grains 

0.60 

420  grains 

4  oz.  350  grains 

9  oz.  263  grains 

0.59 
0.58 
0.57 
0.56 

413  grains 
406  grains 
399  grains 
392  grains 

4  oz.  315  grains 
4  oz.  280  grains 
4  oz.  245  grains 
4  oz.  210  grains 

9  oz.  193  grains 
9  oz.  123  grains 
9  oz.    53  grains 
8  oz.  420  grains 

0.55 

385  grains 

4  oz.  175  grains 

8  oz.  350  grains 

0  54 
0.53 
0.52 
0.51 

378  grains 
371  grains 
364  grains 
357  grains 

4  oz.  140  grains 
4  oz.  105  grains 
4  oz.    70  grains 
4  oz.    35  grains 

8  oz.  280  grains 
8  oz.  210  grains 
8  oz.  140  grains 
8  oz.    70  grains 

0.50 

350  grains 

4  oz. 

8oz. 

0.49 
0.48 
0.47 
0.46 

343  grains 
336  grains 
329  grains 
322  grains 

3  oz.  403  grains 
3  oz.  368  grains 
3  oz.  333  grains 
3  oz.  298  grains 

7  oz.  368  grains 
7  oz.  298  grains 
7  oz.  228  grains 
7  oz.  158  grains 

0.45 

315  grains 

3  oz.  263  grains 

7  oz.    88  grains 

0.44 
0.43 
0.42 
0.41 

308  grains 
301  grains 
294  grains 

287  grains 

3  oz.  228  grains 
3  oz.  193  grains 
3  oz.  158  grains 
3  oz.  123  grains 

7  oz.    18  grains 
6  oz.  385  grains 
6  oz.  315  grains 
6  oz.  245  grains 

f26 


USEFUL   DATA    FOR    DYERS   AND    TEXTILE   CHEMISTS 


PERCENTAGE  TABLES— Continued 


Per  Cent.                    For  10  Lbs.                                     For  50  Lbs. 

For  100  Lbs. 

0 .  40                         280  grains 

3  oz.    88  grains 

6  oz.  175  grains 

0.39 
0.38 
0.37 
0.36 

273  grains 
266  grains 
259  grains 
252  grains 

3  oz.    53  grains 
3  oz.    18  grains 
2  oz.  420  grains 
2  oz.  385  grains 

6  oz.  105  grains 
6  oz.    35  grains 
5  oz.  403  grains 
5  oz.  333  grains 

0.35 

245  grains 

2  oz.  350  grains 

5  oz.  263  grains 

0.34 
0.33 
0.32 
0.31 

238  grains 
231  grains 
224  grains 
217  grains 

2  oz.  315  grains 
2  oz.  280  grains 
2  oz.  245  grains 
2  oz.  210  grains 

5  oz.  193  grains 
5  oz.  123  grains 
5  oz.    53  grains 
4  oz.  420  grains 

0.30 

210  grains 

2  oz.  175  grains 

4  oz.  350  grains 

0.29 
0.28 
0.27 
0.26 

203  grains 
196  grains 
189  grains 
182  grains 

2  oz.  140  grains 
2  oz.  105  grains 
2  oz.    70  grains 
2  oz.    35  grains 

4  oz.  280  grains 
4  oz.  210  grains 
4  oz.  140  grains 
4  oz.     70  grains 

0.25 

175  grains 

2  oz. 

4o;. 

0.24 
0.23 
0.22 
0.21 

168  grains 
161  grains 
154  grains 
147  grains 

1  oz.  403  grains 
1  oz.  368  grains 
1  oz.  333  grains 
1  oz.  298  grains 

3  oz.  368  grains 
3  oz.  298  grains 
3  oz.  228  grains 
3  oz.  158  grains 

0.20 

140  grains 

1  oz.  263  grains 

3  oz.    88  grains 

0.19 
0.18 
0.17 
0.16 

133  grains 
126  grains 
119  grains 
112  grains 

1  oz.  228  grains 
1  oz.  193  grains 
1  oz.  158  grains 
1  oz.  123  grains 

3  oz.     18  grains 
2  oz.  385  grains 
2  oz.  315  grains 
2  oz.  245  grains 

0.15 

105  grains 

1  oz.    88  grains 

2  oz.  175  grains 

0.14 
0.13 
0.12 
0.11 

98  grains 
91  grains 
84  grains 
77  grains 

1  oz.     53  grains 

1  oz.    18  grains 

420  grains 

385  grains 

2  oz.  105  grains 
2  oz.    35  grains 
1  oz.  403  grains 
1  oz.  333  grains 

0.10 

70  grains 

350  grains 

1  oz.  263  grains 

0.09 
0.08 
0.07 
0.06 

63  grains 
56  grains 
49  grains 
42  grains 

315  grains 
280  grains 
245  g;:uns 
210  grains 

1  oz.  193  grains 

1  oz.  123  grains 

1  oz.    53  grains 

420  grains 

PERCENTAGE  TABLES   FOR   DYEING 
PERCENTAGE  TABLES— Continued 


727 


Per  Cent. 

For  10  Lbs. 

For  50  Lbs. 

For  100  Lbs. 

0.05 

35  grains 

175  grains 

350  grains 

0.04 
0.03 
0.02 
0.01 

28  grains 

21  grains 

14  grains 

7  grains 

140  grains 

105  grains 

70  grains 

35  grains 

280  grains 

210  grains 

140  grains 

70  grains 

The  following  example  will  illustrate  the  use  of   this   table:     How   much   dyestuff 
would  be  required  for  2.23  per  cent  on  70  lbs.  of  material? 


For  50  lbs.       2%  equals  1  lb. 
For  20  lbs.       2%  equals 
For  50  lbs.  0.23  7o  equals 
For  20  lbs.  0.23%  equals 


6  oz.  176  grains 

1  oz.  338  grains 

322  grains 


For 


70  lbs.  2.23%  equals  1  lb.  8  oz.  429  grains 


TABLE   SHOWING    THE   AMOUNTS   OF   SODIUM    NITRITE,    ACID,    AND 
DEVELOPER  REQUIRED   FOR   DIAZOTIZING 


DvcstufT. 
Per  Cent. 

Sodium  Nitrite 
Per  Cent. 

Sulphuric  Acid 
168°  Tw. 
Per  Cent. 

Or  H.vdrochloric 

Acid  in  Place  of 

Sulphuric. 

Per  Cent. 

Developer. 
Per  Cent. 

1 

2 

1 

2 

3 

0.5 

1 

u 

2J 

H 

0.6 

n 

H 

3 

41 

0.7 

2 

If 

3^ 

51 

0.8 

2h 

2 

4 

6 

0.9 

3 

2 

4 

6 

31 

2h 

5 

Ih 

4 

2h 

5 

7^ 

41 

2h 

5 

7i 

5 

2* 

5 

71 

These  figures  are  not  supposed  to  be  in  exact  chemical  proportion,  but 
for  practical  reasons  a  sufficient  excess  of  developer  is  prescribed.  Good 
results  are  to  be  obtained  from  these  quantities  only  when  the  proportion 
of  dyed  material  to  water  is  1  :  15. 


728 


USEFUL   DATA   FOR   DYERS  AND   TEXTILE   CHEMISTS 


TABLE  OF  ATOMIC  WEIGHTS  OF  PRINCIPAL  ELEMENTS 

0=16 


Element. 


Symbol. 


Aluminium . 
Antimony . 
Arsenic. ... 
Barium ... 
Bismuth. . . 

Boron 

Bromine . . . 
Cadmium. . 
Calcium . . .  . 

Carbon 

Cerium.  .  .  . 
Chlorine . . . 
Chromium . 

Cobalt 

Copper .... 
Fluorine ... 

Gold 

Hj'drogen . . 

Iodine 

Iron 

Lead 


Al 

Sb 

As 

Ba 

Bi 

B 

Br 

Cd 

Ca 

C 

Ce 

CI 

Cr 

Co 

Cu 

Fl 

Au 

H 

I 

Fe 

Pb 


At.  Wt. 

27 

1 

120 

75 

137.4  1 

208 

5 

11. 

79. 

96 

112. 

4 

40. 

12. 

140. 

35 

5 

52 

1 

59 

63 

6 

19 

197 

2 

1 

01 

126 

85 

56 

206 

9 

Element. 


Magnesium  . 
Manganese .  . 
Mercury .  .  .  . 
Molybdenum 

Nickel 

Nitrogen .  .  .  . 

Oxygen 

Phosphorus.  . 
Platinum .  .  .  . 
Potassium .  .  . 

Silicon 

Silver 

Sodium 

Strontium.  .  . 

Sulphur 

Tin 

Titanium . . .  . 
Tungsten . . .  . 
Uranium .  .  .  . 
Vanadium .  .  . 
Zinc 


Symbol. 


Mg 
Mn 
Hg 
Mo 

Ni 

N 

O 

P 

Pt 

K 

Si 

Ag 

Na 

Sr 

S 

Sn 

Ti 

W 

U 

V 

Zn 


At.  Wt. 


24.36 
55. 
203. 
96. 

58.7 
14.04 
16. 
31. 

194.8 
39.15 
28.4 

107.^3 
23.05 
87.0 
32.06 

118.5 
48. 

184. 

239.5 
51.2 
65.4 


TABLE    OF    FORMULA    AND    MOLECULAR    WEIGHTS 
CHEMICALS   USED  IN  DYEING 


OF     PRINCIPAL 


Name. 


Acetate  of  alumina 

Acetate  of  ammonia 

Acetate  of  chrome  (basic) .  . 
Acetate  of  chrome  (normal) 

Acetate  of  lime 

Acetate  of  nickel 

Acetate  of  soda 

Acetate  of  tin 

Acetic  acid 

Acetine 

Acid  sodium  sulphate 

Acid  sodium  sulphite 

Alcohol 

Alpha-naphthylamine 

Alum  (potash) 

Aluminium  chloride 

Aluminium  sulpho-acetate .  , 
Ammonia 


Formula. 


Al2(C2H302)2 
NH4C2H3O2 

Cr2(C2H302)4-(OH)2 
Cr2(C2H302)6 

Ca(C2H302)2 

Ni(C2H302)2 

NaC2H302-3H20 

Sn(C2H302)2 

CH3COOH 

C3Ho(C2H302)3 

NaHS04 

NaHSOs 

C2H5OH 

C10H-NH2 

Al2(S04)3K2S04-24H20 

AloCle 

Al2S04(C2H302)4 

NH3 


Mi.l.  Wt. 


408 

77 
374 
458 
158 
177 
136 
237 

60 
218 
120 
104 

46 
143 
949 
267 
386 

17 


TABLE   OF   PRINCIPAL   CHEMICALS 


729 


TABLE    OF    FORMULA    AND    MOLECULAR    WEIGHTS     OF 
CHEMICALS   USED   IN   BYFjy^G— Continued 


PRINCIPAL 


Xame. 


Ammonium  chloride 

Ammonium  tin  chloride .  . 
Ammonium  vanadate .... 

Aniline 

Aniline  salt 

Antimony  fluoride 

Antimonj^  oxide 

Antimony  salt 

Antimony  sodium  fluoride 

Barium  chloride 

Benzene 

Beta-naphthol 

Bichromate  of  soda 

Bichromate  of  potash .... 

Bisulphite  of  chrome 

Borax 

Calcium  chloride 

Caustic  lime 

Caustic  soda 

Caustic  potash 

Cerium  chloride 

Chalk 

Chlorate  of  alumina 

Chloride  of  chrome  (basic) 

Chlorate  of  potash 

Chlorate  of  sodium 

Chromate  of  chrome 

Chromate  of  lead 

Chrome  alum 

Chrome  oxide 

Chromium  nitro-acetate .  .  . 

Common  salt 

Cupric  chloride 

Double  chloride  of  tin 

Ferric  acetate 

Ferric  chloride 

Ferrous  acetate 

Ferrous  chloride 

Ferrous  sulphate 

Fluoride  of  chrome 

Glaubersalt 

Glycerin 

Hydrate  of  alumina 

Hydrochloric  acid 

Hydrofluoric  acid 

Hyposulphite  of  soda .... 


Formula. 

Mol.  Wt. 

NH4CI 

54 

SnCl4-2NH4CI 

367 

(NH4)3V04 

169 

C6H5NH2 

93 

CeH^NHo-HCl 

130 

SbFs 

177 

SbsOa 

288 

SbF3(NH4)2S04 

309 

SbFsNaF 

219 

BaC1.2-2H20 

244 

CeHe 

78 

CioHt-OH 

144 

Na2Cr207-2H20 

298 

KoCr207 

295 

Cr2(HSO.,)6 

591 

Na2B4O7-10H2O 

382 

CaCl2 

111 

CaO 

56 

NaOH 

40 

KOH 

56 

CeCls 

246 

CaCOs 

100 

Al2(C103)6 

555 

Cr.Cl.COH)^ 

243 

KCIO3 

123 

NaClOs 

107 

Cr2(Cr04)3 

453 

PbCr04 

323 

Cr2  (804)3X2804  •24H2O 

999 

Cr204 

152 

Cr2(N03)3(C2H302)3 

467 

NaCl 

59 

CuCL-2H20 

171 

SnCl4-3H20 

314 

Fe2(C2H302)6 

466 

Fe2Cl6 

325 

Fe(C2H302)2 

174 

FeClo 

127 

FeS04-7H20 

278 

CroFe-SHoO 

362 

Na3S04  •  IOH2O 

322 

C3H5(OH)3 

92 

Al2(OH)6 

541 

HCl 

36 

HF 

20 

NajS-A-SHsO 

248 

730 


USEFUL   DATA   FOR   DYERS  AND   TEXTILE   CHEMISTS 


TABLE    OF    FORMULA    AND    MOLECULAR    WEIGHTS  OF    PRINCIPAL 
CHEMICALS   USED  IN   DYEING— Continued 


Nanip. 


Lactic  acid 

Magnesium  chloride 

Manganese  chloride 

Nitrate  of  chrome 

Nitrate  of  lead 

Nitric  acid 

Oxalate  of  ammonia 

Oxalate  of  antimony 

Oxalic  acid 

Oxide  of  lead 

Paranitraniline 

Permanganate  of  potash 

Peroxide  of  hydrogen 

Phenol 

Phosphate  of  soda 

Potash 

Potassium  oxalate 

Red  prussiate 

Resorcine 

Silicate  of  soda 

Sugar  of  lead 

Sulphate  of  alumina 

Sulphate  of  cadmium 

Sulphate  of  copper 

Sulphate  of  lead 

Sulphate  of  magnesium 

Sulphate  of  nickel 

Sulphate  of  zinc 

Sulphocyanide  of  ammonia 

Sulphocyanide  of  copper 

Sulphocyanide  of  iron 

Sulphocyanide  of  potash 

Sulphuric  a/!id  (Oil  of  vitriol) .  .  .  . 

Sulphurous  acid 

Soda  calcined  (soda  ash) 

Soda  crystallized 

Sodium  aluminate 

Sodium  bisuljihitc 

Sodium  hydrosulphite  crystallized 

Sodium  nitrite 

Sodium  peroxide 

Sodium  sulphide  crystallized 

Stannatc  of  soda 

Stannic  hydrate 

Stannous  hydrate 

Tannin 


l^Di-niula. 


CsHeOs 

MgCU-GHoO 

MnCl2-4H20 

Cr2(N03)6 
Pb(N03)2 
HNO3 

(NH4)2C204-H20 

Sb(C204K)3-6H20 

C204H2-2H20 

PbO 

C6H4(N02)NH2 

KMn04 

H2O2 

CeHsOH 

Na2HP04-12H20 

K2C03-2H20 

KHC2O4 

Kf,Fe2(CN)i2 

C6H4(OH)2 

Na2Si,09 

Pb(C2H302)2-3H20 

Al2(S04)3-18H20 

CdS04-2H20 

CuS04-5H20 

PbS04 

MgS04-7H20 

NiS04-7H20 

ZnS04-7H20 

NH4SCN 

Cu(SCN)2 

Fe(SCN)2 

KSCN 

H2SO4 

SO2 

Na2C03 

Na2CO3-10H2O 

NacAlaOs 

NaHSOs 

Na.S204-2H20 

NaN02 

Na202 

Na2S-9H20 

NasSnOs 

SnO(OH)2 

Sn(OH)2 

CuHioOg 


Mol.  Wt. 


90 
203 
198 
476 
331 
63 
142 
610 
126 
223 
138 
158 
34 
94 
354 
174 
128 
059 
110 
304 
379 
667 
244 
250 
302 
247 
281 
288 
76 
180 
172 
97 
98 
64 
106 
286 
289 
104 
194 
69 
78 
240 
213 
169 
153 
322 


TABLE   OF   PRINCIPAL   CHEMICALS 


731 


TABLE    OF    FORMULA    AND    MOLECULAR    WEIGHTS    OF    PRINCIPAL 
CHEMICALS   USED   IN    BYEING—Continued 


Name. 


Tartar 

Tartar  emetic 

Tartar  substitute.  .  .  . 

Tartaric  acid 

Thiosulphate  of  soda 

Tin  chloride 

Tin  salt 

Tungstate  of  soda .  .  . 

Water 

Yellow  prussiate 

Zinc  chloride 


Formula. 


KH(C4H406) 

K(SbO)C4H406 

NaHS04 

C4H6O6 

Na2S203-5H20 

SnCU 

SnCl,  •  2H2O 

NaoW04-2H20 

H2O 

K4Fe(CN)6-3H20 

ZnCl, 


H2O 


ISIol.  Wt. 


188 
332 
120 
150 
248 
260 
225 
330 
18 
423 
136 


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Baechler,  M.  Ueber  ein  Oxydationsprodukt  des  Alizarins  mit  Ferricyankalium  in 
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INDEX  OF  EXPERIMENTS 


Absorbent  cotton,  bleaching  of,  150 
Acid  bath  with  substantive  dyes,  302 
Acid-chrome  dyes,  use,  362 
Acid  colors,  use  of  acetic  acid  in  dyeing  of, 
195 

—  dyes  on  cotton,  representative,  236 

silk,  representative,  236 

wool,  representative,  236 

,  action  of,  174 

,  after-treatment  of  with  chrome,  220 

,  dyeing  of  silk  with,  219 

,  in  a  neutral  bath,  193 

,  on  union  goods,  547 

,  use  of  on  cotton,  219 

—  in  dyeing  acid  colors,  influence  of,  193 
Acidified  wool,  dyeing  of,  194 

Acids,  action  of  on  wool  and  cotton,  66 
After-chromed  dyes,  general  properties  of, 

157 
After-mordanting  with  chrome,  361 
After-treating  basic  dyes  on  silk,  253 
After-treatment  with  bluestone,  288 

chrome,  288 

iron  salts,  290 

Alkali,  blue,  dyeing  of,  194 
Alkalies,  action  of  on  fibers,  67 
Ammonium  acetate  in  dyebath,  302 
Aniline  black,  after  chrome  method  for, 

463 

,  ageing  process  for,  466 

,  one  bath  process,  464 

,  use  of  bluestone,  466 

,  use  of  manganese  chloride  in,  469 

,  use  of  vanadium  salts  in,  469 

Anti-chlor  in  bleaching,  150 
Archil,  method  of  dyeing,  511 


Basic  colors,  dyeing  cotton  in  one  bath 

with,  269 
,   general  method  of  dyeing  cotton 

with,  267 

—  dyes,  action  of,  175 

,  compared  with  acid  dyes,  254 

,  dyeing  in  neutral  bath,  254 

,  dyeing  silk  with,  252 

,  effect  of  hard  water  in  dyeing  with, 

254 
,  general  method  of  dyeing  on  wool, 

254 

on  cotton,  274 

silk,  274 

union  goods,  548 

Bistre  on  cotton,  520 

Bleaching  powder,  action  of  on  fibers,  69 

—  wool,  by  sulphur  process,  114 
,  by  tinting,  114 

with  permanganate,  115 

sodium  busulphite,  114 

sodium  peroxide,  115 

Blue  mordant,   use  of  in  cotton  dyeing, 

220 
Boiled-off  liquor,  use  of  in  dyeing  silk,  219 

Carbonizing  process,  illustrating  the,  67 
Chrome  black,  dyeing  with,  363 

—  green  on  cotton,  521 

—  orange  on  cotton,  517 

—  yellow  on  cotton,  516 
Chromotrop  dyes,  use  of,  221 
Ciba-blue,  use  of,  450 
Cochineal,  method  of  dyeing,  511 
Copperas  vat  for  indigo,  447 

Cotton  bleaching,  acid  treatments  in,  152 


751 


752 


INDEX 


Cotton  bleaching,  softening  and  tinting 

in,  151 

,  tinting  process,  150 

,  use  of  acetic  acid  in,  151 

,  use  of  lime  boil  in,  152 

, sodium  hypochlorite  in,  152 

with  chloride  of  lime,  150 

,  —  permanganates,  153 

,  —  peroxides,  152 

— ,  dyeing  of  acid  dyes  on,  19 

Coupled    dyes,     general     properties     of, 

157 
Coupling  process  of  dyeing,  338 
Cuprammonium    solution,    action    of    on 

cotton,  69 
Cutch,  method  of  dyeing,  511 

Developed  black,  337 
on  silk,  339 

—  blue,  337 

—  brown,  337 

—  dyes,  after-treatment  of,  337 

,  general  method  for,  335 

,  properties  of,  157 

,  shading  of,  337 

Diazotized  colors,  335 

Direct  cotton  colors,  286 
Dyeing  in  cold  bath,  289 

—  mordanting  colors,  360 

—  process,  study  of  factors  in,  604 
Dyestuffs,  action  of  on  fibers,  158 
— , wool,  159 

Ecru  silk,  dyeing  of,  252 
Exhaustion  of  dyebath,  193,  605 
Equilibrium    of    d^-ebath,    conditions    of, 
604 


Fast 


ness,  methods  of  tabulating  tests  for, 
243 
—  of     dyes    to    carbonizing,    testing    of, 
241 

■ chloring,  testing  of,  242 

■  —  crocking,  243 

—  cross-dyeing,  testing  of,  242 

fulling,  testing  of,  240 

light,  testing  of,  240 

perspiration,  testing  of,  241 

stoving,  testing  of,  242 

washing,  testing  of,  240 

water,  testing  of,  241 


Formaldehyde,  use  of  in  dyeing,  288 
Fustic  method  of  dyeing,  510 

Glaubersalt,  use  of  in  dyebath,  193 

Heat,  action  of  on  fibers,  70 
Hydrosulphite  vat  for  indigo,  446 
Hematine,  dyeing  with,  484 
Hydrochloric  acid,  action  of  on  silk,  67 

Ice  colors,  336 

Indanthrene  blue,  use  of,  450 

—  colors,  pink  with,  450 

—  yellow,  use  of,  450 
Indigo  extract,  449 
— ,  reactions  of,  448 

—  solution,  preparation  of,  445 
Iron  buff  on  cotton  518 

—  gray  on  cotton,  519 

—  salts,  effect  of  in  dyeing,  360 

Janus  dyes,  use  of,  269 

Keratine  in  wool,  159 
Khaki  on  cotton,  522 

Logwood  black,  on  cotton,  487 
silk,  490 

—  blue  on  cotton,  490 

—  chrome  black  on  cotton,  488 

—  direct  black,  480 

—  dyeing  in  one  bath,  364 
— ,  —  on  wool.  484 

— ■,  effect  of  over  chroming,  484 

—  extract,  valuation  of,  490 

— ,  shading  of  with  alizarine  yellow,  48£ 

— , fustic,  485 

— ,  use  of  iron  mordant  with,  485 

—  with  aluminium  mordant,  487 

—  with  copper  mordant,  489 

—  with  tin  mordant,  ^87 

jMadder,  method  of  dyeing,  510 
Manganese  brown  on  cotton,  520 
IMercerization  of  cotton,  68 
INIeta-chrome  dyeing,  363 
Metallic  salts,  action  of  on  cotton,  68 

, fibers,  68 

Mixed  colors,  dyeing  of,  605 
Mordant  dyes,  action  of,  175 
Mordants,  action  of  on  fibers,  68 


INDEX 


753 


Mordants  on  wool,  comparison,  of  361 
Moisture,  effect  of  in  textile  fibers,  70 

Naphthol  dyes,  general  properties  of,  157 

Organic  acids,  action  of  on  cotton,  667 
Oxidized  dyes,  general  properties  of,  158 
Oxidizing  agents,  action  of  on  cotton,  70 

Padder,  dyeing  with,  364 

Peroxide  bleaching,  effect  of  iron  in,  153 

Phthalein  dyes,  use  of,  195 

Pigment  dyes,  action  of,  176 

,  general  properties  of,  158 

Primuliiie,  335 

—  on  silk,  338 

Prussia  blue  on  cotton,  522 

wool,  522 

Pyrolignite  of  iron,  after-treating  with,  290 

Quercitron,  method  of  dyeing,  511 

Salt  colors,  286 

— ,  influence  of  amount  of  in  bath,  287 
Sandal-wood,  dyeing  with,  364 
Scouring  cotton  with  caustic  soda,  105 

soap,  106 

soda  ash,  105 

soluble  oil,  106 

Scouring  of  raw  silk,  106 

—  wool  by  emulsion  process,  105 

,  effect  of  alkalies  in,  105 

,  use  of  potash  in,  105 

—  woolen  yarn,  105 

containing  iron,  105 

Scrooping  effect  on  silk,  67 
Shading  substantive  dyes,  289 
Silk,  dyeing  of  with  acid  dyes,  219 

in  neutral  soap  bath,  252 

,  use  of  acetic  acid  in,  219 

, of  boiled-off  liquor  in,  219 

— ,  —  with  basic  colors,  252 

Silk-cotton  goods,  two  color  effects  on,  568 

,  various  methods  of  dyeing,  567 

Soap,  use  of,  in  dyeing,  288 

Soda  ash,  use  of,  in  dyeing,  287 

Sodium  stannate,  use  of  after  mordanting, 

220 
Solid  solution  in  dyeing  process,  159 
Souple  silk,  dyeing  of,  252 


Substantive  colors,  stripping  of  with  chlo- 
ride of  lime,  238 

, hydrosulphite,  239 

, titanous  salts,  239 

— dyes,  action  of,  175 

,  after-treatment  with  chrome,  304 

, chromium  fluoride,  304 

,  dyeing  wool  with,  302 

,  general  properties  of,  157 

not  dyeing  wool,  304 

on  cotton,  dyeing  of,  286 

silk,  general  method  for,  305 

union  goods,  548 

with  logwood,  289 

Sulphur  blue,  method  of  dyeing,  404 

—  dyes,  topping  of,  404 

,  after  treatment  of  with  chrome,  403 

,  general  method  of  applying,  403 

,  black  dyeing  with,  403 

.  dyeing  khaki  with,  404 

,  general  properties  of,  157 

Sulphuric  acid,  action  of  on  cotton,  67 

Tannin,  fixing  with  antimony  salts,  269 

— ,  —  with  copperas,  269 

— ,  method  of  fixing  with  tartar  emetic, 

267 
Temperature  of  dyebath,  287 
Tests  for  fastness,  methods  of  tabulating, 

243 
Thio-indigo  red,  dyeing  with,  449 
Tin  mordant  dyeing  on,  363 
Topping  with  aniline  black,  290 

—  with  cutch,  290 

Turkey  red,  old  process  for,  366 

,  short  process  for,  369 

Two  color,  effects  on  union  goods,  548 

Union  goods,  substantive  dyes  on,  303 

—  dyeing,  various  methods  of,  549 

Vat  dyes,  general  properties  of,  157 

Woaded  black,  486 

Wool,  affinity  of  for  dyes,  159 

— ,  general  method  of  dyeing,  193 

Zinc,  chloride,  action  of  on  cotton,  69 

—  lime  vat  for  indigo,  448 


SUBJECT  INDEX 


Absorbent  cotton,  preparation  of,  143 
Acetic  acid,  use  of  in  cotton  bleaching, 

, in  dyeing,  181 

Acid  and  basic  dyes,   distinguishing 
tween,  672 

—  colors,  methods  of  stripping,  238 

—  dyes,  action  of  on  cotton,  165 
^  —  with  hard  water,  179 
chemical  classification  of,  177 
chief  defects  of,  178 

dissolving  of,  209 
fastness  of,  178 
general  characteristics  of,  177 

—  properties  of,  156 

—  use  of,  177 
list  of  principal,  232 

on  jute,  576 

precautions  for  use  of,  179 
use  of  in  neutral  bath,  183 

on  cotton,  202 

silk,  163,  197 

wool,  160 

—  in  fabrics,  estimation  of,  692 

—  indigo  extract,  431 

—  potassium  oxalate,  use  of,  279 
Acids,  action  of  on  textiles,  36 
Acridine  dyes,  247 

Adjective  dyes,  162,  340 
Adulteration  in  dyes,  detection  of,  672 
After-chromed  acid  dyes,  206 

—  dyes,  use  of  on  wool,  162 
After-treatment  with  bluestone,  282 
chrome,  282 

formaldehyde,  282 

Ageing  machine,  364,  370 

for  aniline  1  Ir.ck,  464 

cloth,  462 

warps,  463 


133 


be- 


Algol  dyes,  441 
Alizarine,  496 

— ,  chemical  reactions  of,  496 
Alkalies,  action  of  on  fibers,  40 
Alkanna,  10 

Alpha-naphthol,  313,  321 
Alpha-naphthol-parasulphonic  acid,  313 
Alpha-naphthylamine,  332 

—  claret,  332 

—  salt  S,  333 
Aluminium  acetate,  282 
Aluminium-tannin  mordant,  261 
Amend's  process  of  mordanting,  345 
Amino-azo-benzene,  321,  331 

—  developers,  309 
Amino-diphenylamine,  313 
Amino-naphthol-sulphonic  acid  G,  313 
Ammoniacal  cochineal,  506 
Ammonium  acetate,   method  of  making, 

182  ■  ■ 
,  use  of  in  dyeing,  182 

—  sulphate,  use  of  in  dyeing,  182 

—  sulphocyanide,  use  of  in  dyeing,  187 
Analysis  of  textile  fabrics,  687 

Ancient  dyestuffs,  comparison  with  mod- 
ern dyes,  14 
,  limitations  of,  13 

—  methods  of  dyeing,  15 

Angola  yarns,  fastness  of  colors  for,  623 
Aniline,  321 

—  black,  451 

,  formulas  for,  457 

,  Green's  process  for,  457 

on  silk,  460 

wool,  460 

,  oxidizing  process,  452 

,  single  bath  process,  452 

,  steam  process,  452 


755 


756 


INDEX 


Aniline  black  ungreenable,  451 

—  dyes,  definition  of,  248 

—  inks,  660 

Animalized  cotton,  165,  203 
Aninializing  cotton,  36 
Anti-chlor,  use  of  in  bleaching,  131 
Antiinonine,  266 

Antimonj'  oxalate,  266 

—  salts,  266 

Antimony-sodium  fluoride,  266 
Antimony-tannin  mordant,  259 
Anthraquinone  dyes,  405 

—  vat  bues,  441 

Apparatus  for  dyeing  union  goods,  525 

decatizing,  65 

dyeing,  211 

Archil,  498.  499 

— ,  chemical,  reactions  of,  499 

—  liquor,  499 

Artificial  flowers,  dyeing  of,  641 

—  horsehair,  579 

—  silk,  dyeing  blacks  on,  581 
,  dyeing  of,  578 

- — — ,  general  methods  of  dyeing,  174 

Artists'  colors,  650 

Ash  in  fabrics,  estimation  of,  692 

Assistants  used  in  dyeing,  168 

Aurantine,  495 

Auxochrome,  169 

Azine  dyes,  247 

Azo  basic  dyes,  247 

—  black  base,  321 

base  C),  332  • 

base  OX,  332 

—  garnet,  331 

—  maroon,  332 
Azophor  blue  D,  332 

—  red  PX,  319 

Back  chroming  of  logwood,  479 

—  drying  machine,  510 
Bakelite,  dyeing  of,  647 
Bark  extract,  500 

Basic  colors  in  dyeing  linen,  574 

,' practical  dyeing  of,  273 

,  use  of  on  cotton,  255 

—  dyes,  action  of  on  cotton,  165 

,  action  of  reducing  agents  on,  247 

,  characteristics  of,  247 

,  dissolving  of,  250 

,  general  properties  of,  156 


Basic  colors,  list  of  principal,  270 

,  topping  substantive  dyes  with,  252 

,  use  of  on  silk,  163,  249 

, for  wool,  160,  251 

on  jute,  576 

Bast  silk,  197 

Batik  style  of  dyeing,  4 

Bed  feathers,  bleaching  of,  635 

Beetling  machine,  587 

for  heavy  cloth,  683 

Benzidine,  321 

—  developer,  314 
Benzo  nitrol,  319 
Berlin  blue,  523 
Beta-uaphthol,  311 
Beta-naphthylamine,  321 
Bibliography  of  dyeing,  733 
Bistramine  brown,  462 
Bistre,  520 

Black  cochineal,  505 

—  dyed  cotton,  analysis  of,  697 
Bleacher's  assistants,  composition  of,  118 
Bleaching  cotton  with  hypochlorites,  122 

—  fine  3'arns,  vacuum  kier  for,  145 

—  machine  for  knitgoods,  146 
raw  stock,  151 

—  powder,  apparatus  for  dissohing,  125 
,  disadvantages  of,  141 

,  properties  of,  125 

—  silk  by  stoving,  113 

with  aqua  regia,  113 

peroxides,  113 

—  with  hypochlorites,  chemical  reactions 

in,  126 

—  wool  by  tinting  process,  107 

,  comparative  methods  of,  113 

,  gas  process  for,  108 

with  permanganates,  112 

peroxides,  110 

sodium  bisulphite,  108 

Blue  developer  AX',  313 

—  spirits,  523 

Boiled-off   compounds,    efi'ect   of   neutral 
salts  in,  122 

—  liquors,-  use  of  in  dyeing.  97 

—  3'arns,  change  in  count  of,  119 
Boiling-off  of  silk,  96 

Boiling-out  cotton,  effect  of  different  alka- 
lies in,  122 
— ,  discu-ssion  of,  119 

—  of  cotton,  89 


INDEX 


757 


Boiling-out  yarn,  effect   of    on    physical 

properties,  120 
Bonsor's  fast  direct  black,  47G 
Bookbinders'  cloth,  fastness  of  colors  for, 

623 
Bordeaux  developer,  311 
Brightening  of  silk,  39,  199 
Bristles,  dyeing  of,  639 
Brown  developer,  313 
Brushing  nuicliiue  for  piece  goods,  659 
Burl  dyeing,  538 
Button  material,  tlyeing  of,  645 

Calcined  glaubersalt,  186 

Calcium  acetate,  use  of  in  dyeing,  353 

Calculations  in  dyeing,  187,  712 

Calender  for  jute,  573 

producing  silk  finish,  680 

—  with  expander,  490 
Campeachy  wood,  471 
Candles,  dyeing  of,  663 
Capacity  of  tanks,  713 
Capillary  speed  of  dyestuffs,  676 
Carbazol  dj'es,  405 

—  vat  dyes,  444 

Carbonized  shoddy,  method  of  dyeing,  181 

—  wool,  after-treatment  of,  75 
Carbonizing,  36,  188 

—  with  aluminium  chloride,  75 

hydrochloric  acid,  75 

sulphuric  acid,  74 

—  scoured  wool,  74 
Carmine  lake,  507 
Carminic  acid,  505 

Carpet  yarns,  fastness  of  colors  for,  621 
Carriers  for  lakes,  648 
Catechin,  501 
Catechu,  501 
Catechu-tannic  acid,  501 
Catechuic  Acid,  502 
Celluloid,  dyeing  of,  644 
Centrifugal  machine  for  cloth,  310 
Cerasine  dj'es,  664 
Chardonnet  silk,  578 
Cheese  dyeing  machine,  391 
Chemic  in  cotton  bleaching,  125 
Chemical  theory  of  dyeing,  582 
Chemicals  used  in  dyeing,  728 
Chalybeate  water,  216 
China  grass,  575 
Chloranisidine,  321 


Chloranisidine  scarlet,  333 

Chlored  wool,  54 

Chloride  of  soda,  134 

Chlorinated  wool,  55 

Chlorine  compounds,  action  of  on  fibers,  54 

Cholesterol,  71 

Chromate  process,  352 

Chrome,  action  of  in  dyeing,  207 

—  developed  dyes,  374 

—  dyes,  340,  356 

—  green,  521 

—  orange,  517 

Chrome-tanned  leather,  dyeing  of,  628 

Chrome  yellow,  516 

Chromium  fluoride,  after-treatment  with. 

299 
Chromophor,  169 

Chromotrop,  method  of  application,  207 
Chrysoidine,  314 
Ciba  dyes,  437 
Cibanone  dyes,  442 
Clarax  bleaching  compound,  152 
Classification  of  dyes,  154,  224 
Cloth  doubling  machine,  634 

—  spreading  machine,  532 

—  trimmer,  646 

Coal-tar  dj'es,  discovery  of,  155 

,  introduction  of,  12 

Cochineal,  505 

— ,  reactions  of,  505 

— ,  with  difi'erent  mordants,  505 

—  carmine,  507 

Coir  fiber,  dyeing  of,  577 

Cold  bath,  dyeing  in,  280 

Collodion  silk,  578 

Color  and  chemical  constitution,  relation 

between,  169 
Color-lakes,  preparation  of,  648 
Colors,  on  cotton  testing  fastness  of,  616 

wool,  testing  fastness  of,  608 

silk,  testing  fastness  of,  618 

Condcnsite,  dyeing  of,  647 
Conditioning  of  textiles,  59,  691 

—  oven  for  textiles,  57 
Continuous  dyeing  machine,  398 
Conversion  tables,  704 

Cop  dyeing  machine,  268,  272,  277,  391 

,  for  indigo,  425 

,  —  vat  colors,  432 

Copperas  black  with  logwood,  479' 

— ,  use  of  in  fixing  tannin  mordant,  260 


758 


INDEX 


Copperas  vat  for  indigo,  413,  422 
Copying  inks,  660 
Correction  for  hard  water,  353 
Cotton,  action  of  acids  on,  36 

acid  dyes  on,  165 

after-chrome  dyes  on,  165 

alkalies  on,  41 

basic  dyes  on,  165 

chlorine  on,  56 

dyes  on,  164 

metallic  salts  on,  54 

mordant  dyes  on,  165 

natural  dyes  on,  166 

nitric  acid  on,  36 

organic  acids  on,  37 

potassium  permanganate  on,  56 

substantive  dyes  on,  165 

sulphur  dyes  on,  165 

tannic  acid  on,  39 

vat  dyes  on,  165 

—  and  linen,  distinction  between,  689 
wool,  estimation  of  in  fabrics,  528 

—  bleaching,  acid  treatment  in,  128 

,  action  of  chlorine  in,  117 

,  boiling-out  for,  117 

,  cause  of  tendering,  130 

,  chemical  agents  used  in,  116 

,  continuous  system,  138 

,  different  forms  of,  116 

,  loss  in  strength  in,  130 

, weight  in,  130 

,  machinery  for,  127 

,  method  of  chemicing,  124 

,  methods  of  washing,  000 

,  oxidization  of  fiber,  130 

,  soaping  and  tinting  in,  129 

,  use  of  hj'pochlorites  in,  122 

-,  various  operations  in,  117 

— ,  boiling-out  of,  89 
— ,  dyeing  of  with  acid  colors,  202 
— ,  effect  of  bleaching  on,  130 
— , heat  on,  62 

—  fiber  under  microscope,  527 

— ,  general  methods  of  dyeing,  172 

—  goods,  fastness  of  colors  for,  622 
— ,  impurities  in  raw,  89 

—  linings,  fastness  of  colors,  for  623 
— ,  methods  of  mordanting,  255 

— ,  use  of  in  woolen  goods,  526 
— ,  wetting-out  of,  91 

—  piece  goods,  fastness  of  colors  for,  623 


Cotton  raw  stock,   dyeing  with  sulphur 
colors,  398 

—  skein  yarn,  bleaching  of,  144 

—  warps,  bleaching  of,  144 

,  dyeing  of  in  size,  285 

,  fastness  of  colors  for,  522 

—  wash  fabrics,  dyes  for,  407 

—  yarn,  apparatus  for  dyeing,  212 
Coupled  dyes,  317,  334 
Cow-hair,  dyeing  of,  639 
Crabbing  machine,  open-width,  346 
— ,  machinery  for,  88 

—  process,  63 

—  union  goods,  534 
Craft  dyeing,  3 
Cream  of  tartar,  345 
Crimson  developer,  313 
Crop  madder,  497 
Cudbear,  500 

Cuit  silk,  96 

Cuprammonium  silk,  578 

Curcumine,  508 

Cutch,  501 

— ,  detection  of  on  fibers,  503 

— ,  use  of  in  dyeing,  503 

Cylinder  brushing  machine,  621 

Data  for  dyers,  701 
Decatizing,  apparatus  for,  65 
— ,  effect  on  wool  fiber  in,  66 

—  process,  65 

—  union  goods,  534 
Definition  of  dye  terms,  1 
Degumming  of  silk,  96 
Delahunty  dyeing  machine,  170 
Denims,  dyeing  of,  392 
Density  of  dyebath,  277 

solutions,  707 

Desiccated  glaubersalt,  186 

Developed  dyes  on  silk-cotton  goods,  566 

—  colors,  fastness  of,  308 
on  cotton,  308 

,  properties  of,  308,  329 

—  dyes,  list  of,  333 

,  shading  of,  314 

,  use  of  on  silk,  316 

Developer  A,  313 

—  B,  313 

—  C,  313 

—  D,  314 

—  E,  313 


INDEX 


759 


Developer  F,  313 

—  G,  313 

—  H,  313 

—  J,  313 

Developers,  list  of,  311 
Developing  process,  308 
Dextrin,  testing  for,  676 
Diamalt,  use  of  on  cotton  93 
Diamino-azobenzene  hydrochloride,  314 
Dianisidine,  321 

—  blue,  332 

—  developer,  314 
Diastafor,  use  of  on  cotton,  93 
Diastase,  use  jof  on  cotton,  93 
Diazo-paranitraniline,  318 
Diazotizing  bath,  preparing  of,  310 

—  process,  309 

Dichroic  property  of  dye,  680 
Dioxy-naphthalene,  314 
Diphenyl  black,  461 
Dissociation,  theory  of  dyeing,  588 
Dissolving  dyes,  machinery  for,_  156 

—  dyestuffs,  208 
Divi-divi,  265 
Double-acting  gig,  605 
Double  antimony  fluoride,  266 
Double-cylinder  gig,  611 
Double-jigger  for  sulphur  colors,  396 
Doubling  machine  for  warps,  226 
Dressgoods,  fastness  of  colors  for,  622 
Dreze-Michaelis  dyeing  machine,  189 
Drum  machine  for  leather  dyeing,  625 
Dryer  for  raw  stock,  191 

Drying  cans,  horizontal,  357 

—  dyed  material,  34 

— ,  effect  of  on  textiles,  60 

—  machine  for  cones  and  tubes,  521 

—  machines,  135 
Dye  salt  I,  313 

II,  313 

IV,  314 

V,  313 

VI,  313 

VII,  313 

—  sticks,  material  used  for,  211 
Dyebath,  general  preparation  of,  180 
— ,  temperature  of,  180 

Dyed  material,  after-treatment  of,  34 
Dyeing  machine  for  para  red,  328 

raw  stock,  163,  164 

,  open  width,  288,  315,  343,  474 


Dyeing,  mechanical  apparatus  for,  22 

—  mixed  fibers,  524 

— ,  practical  processes  of,  20 
— ,  relation  of  to  chemistry,  2 

—  two  color  effects  on  union  goods,  541 

—  union  goods,  534 

—  with  mordant  colors,  352 
Dyepots  for  experimental  tests,  19 
Dyes  for  food  products,  664 

silk  cottongoods,  564 

typewriter  ribbons,  663 

for  union  goods,  542 

wool-silk  fibers,  556 

— ,  normal  qualities  of  fastness  for,  239 

—  not  affected  by  chrome,  374 
— ,  suitable  for  coloring  soap,  660 
— ,  —  —  inks,  660,  662 

— , spirit  lakes,  659 

—  used  in  medicine,  665 
Dyestuff,  definition  of,  2 

—  and  pigment,  difference  between,  1 

—  brands,  method  of  labeling,  223 

—  extracts,  autoclave  for  preparing,  161 

—  manufacturers  in  various  countries,230 

—  tables  of  Schultz,  224 
Dyestuffs,  action  of  metals  on,  210 
— , on  silk,  163 

—  as  indicators,  665 

—  for  leather,  627 

— -  —  tinting  bleached  wool,  109 

—  general  properties  of,  156 
— ,  identification  of,  669 

— ,  manufacturers,  names  of,  230 
— ;  methods  of  classifying,  154 

— , dissolving,  209 

— ,  suitable  for  lakes,  657 
— ,  testing  value  of,  666 

—  used  by  ancients,  8 
Dye-testing,  equipment  for,  16 
Dye-tests,  method  of  making,  18,  180 
Dyevats  for  silk,  211 

Dye  winch  for  cloth,  393 
Dynamite  liquor,  54,  201 

Ecru  silk,  97 

Effect  of  light  on  colors,  609 
Electrical  condition  of  fibers,  61 
Electrolytic  bleach  liquors,  139 

,  method  of  preparing,  141 

,  plant  for,  140 

Electrolyzer  cell  for  bleaching  liquor,  139 


760 


INDEX 


Emeraldine,  451 

Emulsion  process  of  scouring  wool,  72 

Eosin  dyes,  156 

,  use  of  on  cotton,  206 

—  lakes,  652 

Epsom  salts  in  dyes,  testing  for,  676 

Erythrin,  499 

Esser  raw  stock  machine,  172 

Ethyl-beta-naphthylamine,  313 

Evernic  acid,  499 

Exhaustion  of  dyebath.  186,  278,  590,  678 

Expanding  machine  for  cloth,  597 

Experimental  dyebaths,  17 

Extract  wool,  526 

,  method  of  dyeing,  181 

F-acid,  313 

Factors  in  theory  of  dyeing,  600 

Fancy  yarns,  dyeing  of,  190 

,  fastness  of  colors  for,  621 

Fast  blue  developer  AD,  311,  313 

AN,  311 

Fastness  of  colors  on  cotton,  testing  of,  616 

dyes,  239,  607 

substantive  dyes,  280 

—  required  on  various  materials,  243,  619 

—  to  acids,  614 
alkali,  615 

— bleaching,  617 

carbonizing,  614 

chlorine,  617 

crocking,  612 

—  —  cross-dyeing,  617 

decatizing,  616 

fulling,  611 

hot  pressing,  616 

ironing,  616 

laundering,  617 

light,  608 

lime,  615 

mercerizing,  617 

perspiration,  614 

potting,  616 

rubbing,  612 

steaming,  616 

stoving,  615 

street  dust,  615 

sulphuring,  615 

washing,  610 

water,  613 

weather,  613 


Fat  dyes,  664 

Feathers,  bleaching  of,  635 

— ,  dyeing  of,  635 

Fermentation  vat  for  indigo,  413,  417 

Fibroin,  95 

Filters  for  hard  water,  101 

Finishing  blue  spirits,  523 

—  machine  for  half-silk  goods,  555 
Flannels,  fastness  of  colors  for,  622 
Flavine,  500 

Flowers  of  madder,  497 

Foam  dyeing  for  sulphur  colors,  398 

Food  products,  dyestuffs  for,  664 

Formaldehyde,  after-treatment  with,  282 

Formic  acid,  use  of  in  dj'eing,  182 

Foulard  machine,  359 

Franklin  dyeing  machine,  262 

French  purple,  499 

Friction  calender,  563 

—  mangle,  488 

Full  shade,  amount  of  dye  necessary  for, 

678 
Fulling  machines,  85 
^,  process  of,  86 

—  washer  for  flannels,  592 
Fur  dyeing,  632 

Furrol  dyes,  633 

Fuscamine,  462 

Fustic,  492 

— ,  detecting  of  on  fiber,  494 

—  reactions  of  mordants  with,  494 

—  extract,  reactions  of,  492 
Fustin,  494 

Gallalith,  dyeing  of,  647 

Gallo-tannic  acid,  264 

Gall-nut  tannin,  265 

Gambler,  501 

Garanceux,  497 

Garancin,  497 

Genista,  use  of  as  dyestuff,  lO 

Glaubersalt,  effect  of  in  dyeing,  185,  595 

Gloria,  524 

Grain  colors,  509 

Gray  sour  in  cotton  bleaching,  121 

Group  names  of  dyestuffs,  224 

Half-wool,  dyeing  of,  524 

Hard  water,  action  of  in  bleaching,  217 

, dyeing,  216 

, on  substantive  dyes,  278 


INDEX 


761 


Hard  water,  correction  of,  100 

,  definition  of,  21G 

,  effect  of  in  bleaching  and  dyeing, 

104 

,  meaning  of,  100 

,  methods  of  filtering,  101 

Hat  braid,  dyeing  of,  638 

—  material,  G22 

Heat,  action  of  on  fibers,  61 
Heating  dyevats,  methods  for,  28 
Hectograph  inks,  660 
Helidone  dyes,  437 
Hematine,  471 

—  crystals,  474 

—  extract,  474 
Hematoxylin,  471 
Hemp,  dyeing  of,  578 

—  twine,  dyeing  of,  578 
History  of  dyeing,  7 

Horizontal  cylinder  drying  machine,  512 
Horn  buttons,  dyeing  of,  646 
Horsehair,  dyeing  of,  639 
Hosiery  dyeing  machine,  303 

—  yarns,  fastness  of  colors  for,  621 
Hot  water,  effect  of  on  fibers,  63 
Human  hair,  dyeing  of,  639 
Humidity,    effect    of  in     manufacturing 

textiles,  59 
Hydrated  cellulose,  36 
Hydraulic  calender,  502 

—  mangle,  486 

—  press  for  finishing  piece  goods,  698 
Hydro-extracting  dyed  material,  33 
Hydro-extractor  for  cloth,  326 
Hydrogen  peroxide,  110 

Hydron  blue,  375,  444 
Hydrometry,  701 
Hydrosulphite  ammonia  vat,  428 

—  liquor,  preparation  of,  427 
— ,  use  of  in  stripping,  238 

—  vat,  408,  413,  427 
Hygroscopic  properties  of  fibers,  57 

Identification  of  dyes,  682 

Imitation  seal-skin,  dyeing  of,  505 

Indanthrene  dyes,  441 

Indican,  411 

Indicators,  dyes  used  for,  665 

Indigo,  410 

— ,  action  of,  on  fabrics,  413 

Indigo-brown,  410 


Indigo  carmine,  413 

—  derivatives,  436 

—  dye  vat,  421 

—  dyeing,  continuous  methods  of,  417 
on  piece  goods,  416 

range,  420 

—  dyeings,  after-treatment  of,  415 

—  extract,  431 

— ,  extracting  from  plant,  411 

Indigo-gluten,  410 

Indigo,  methods  of  dyeing,  413 

—  mill,  407 

—  salt,  434 

—  solution,  433 

— ,  syntheses  of,  434 

— ,  testing  of,  on  fiber,  435 

—  vats,  433 

,  comparison  of,  429 

— '  — ,  dipping  apparatus  for,  429 

—  white,  412,  433 
Indigoids,  405 
Indigotine,  410 
Indirubin,  410 
Indophenol,  433 
Indophor,  434 
Ingrain  colors,  308,  509 
Ink  powder,  661 

Inks,  preparation  of,  660 
Iron  buff,  518 

—  gray,  519 

—  mordants,  349 
Iron-tannin  mordant,  260 
Ivory,  dyeing  of,  647 

Japonic  acid,  503 

Jigger  dyeing  machine,  303 

dyeing,  352 

for  mordanting  and  dyeing,  354 

sample  dyeing,  394 

sulphur  colors,  394-5 

Jute,  action  of  dyestuffs  on,  156 

— ,  bleaching  of,  575 

— ,  dyeing  of,  575 

— ,  general  methods  of  dyeing,  174 

Kermes,  8,  509 

Khaki  brown,  production  of,  392 
Kier  boiling  in  cotton  bleaching,  118 
Kiers  for  boiling-out  cotton,  90 
Klauder-Weldon  raw  stock  machine,  164 
KJug  raw  stock  machine,  175 


762 


INDEX 


Knitgoods,  bleaching  of,  146 
— ,  drying  iiuu'hinery  for,  149 
— ,  fastno.s.s  of  colors  for.  622 
— ,  machinery  for  bleaching,  149 
Knitting  yarns,  fastness  of  colors  for,  621 


Lac  dye,  509 

Laccainic  acid,  509 

Lactic  acid,  345 

Lactolinc,  345 

Lake  colors,  preparation  of,  649 

Lakes,  dyes  for,  648 

Laws  concerning  dyestuffs,  12 

Leather  dyeing  of,  624 

— ,  preparation  of  for  dyeing,  625 

Lecanoric  acid,  499 

Leveling  properties  of  dyes,  186 

Lighting  of  dyehouse,  30 

Lignorosiu,  345 

Lime  boil  for  cotton,  121 

Linen  dyeing,  571 

— ,  general  methods  of  dyeing,  174 

—  yarn,  boiling  out  of,  572 

Liquid  chlorine,  installation  for  bleaching 
with,  137 

,  use  of  in  cotton  bleaching,  136 

Lists  in  dyed  goods.  218 

piece-goods,  192 

Lithographic  inks,  648 

—  lakes,  '654 
Logwood,  470 

—  black,  fastness  of,  473 

,  on  loose  cotton,  480 

,  one  bath  process,  476 

—  chips  in  dyeing,  471 

— ,  detection  of  on  fiber,  482 

—  dyeing  on  wool,  476 
silk,  481 

—  extract,  472 

,  valuation  of,  475 

— ,  methods  of  extracting,  473 

—  on  cotton  479 
— ,  reactions  of,  482 

Loose  cotton,  bleaching  of,  143 

—  stock,  dyeing  of,  24 

machine  for  indigo  dyeing,  415 

—  wool,  fastness  of  colors  for,  619 
Ludigol,  406 

Lustering  machine  for  wool,  498 
Luteolin,  508 


IMaclurin,  492 
Madder,  496 

—  in  different  mordants,  497 

—  mangle,  535 

Magnesium  chloride,  use  of  in  carbonizing, 
191 

—  sulphate,  after-treatment  with,  283 
Malachite   green,    method  of   dyeing  on 

wool,  251 
Malting  of  cotton,  93 
Manganese  brown,  520 
Mangle  for  cotton  pieces,  478 
Marking  inks,  662 
Maroon  developer,  313 
Mechanical  theory  of  dyeing,  583 
Medieval  colors,  dyestuffs  u.sed  in,  14 
Mclanogen  dyes,  387 
Mercerized  cotton,  action  of  basic  dyes  on, 

165 

,  dyeing  of,  278 

,  test  for,  690 

Mercerizing,  boiling-out  of  cloth  for,  51 

—  b}'  Schreiner  jirocess,  53 

— ,  description  of  operations  in,  44 

—  of  cloth,  48 
cotton,  41 

— ,  skein  method  for,  42 
— ,  warp  method  for,  43 
Merino  yarns,  525 

,  fastness  of  colors  for,  623 

Meta-chroine  i)rocess,  352 
Metallic  mordants,  168 

—  salts,  action  of  on  fibers,  53 
Metals,  action  of  on  dye  solutions,  210 
Meta-nitraniline,  321,  332 
Meta-phenylene-diamine  base,  313 
Meta-]ihenylene-diamine   hydrochloride, 

313 
Meta-phenylene-diamine,  method  of  using, 

330 
Meta-toluylene-diamine  base,  313 
Methods  of  mordanting,  349 
Microscopic  stains,  dyes  for,  665 
Micuit  silk,  96 
Milling  and  fulling,  86 
Mimotannic  acid,  502 
Mineral  dyes,  155,  513 
— •  khaki  on  cotton,  515 
Mixed  dyes,  detection  of,  668 
— -  fibers  in  fabrics,  estimation  of,  688 
Mixes,  dyeing  of,  189 


INDEX 


763 


Moistening  machine  for  finishing  cottons, 

670 
Moisture  in  textile  fibers,  effect  of,  57 
Money  value  of  dye  samples,  666 
Mono-chrome  process,  352 

of  dyeing,  356 

Mono-genetic  dyes,  340 
Mono-sulphonic  acid,  313 
Mordant  assistants,  344 

—  colors,  methods  of  stripping,  238 

—  dyes,  340 

,  classification  of,  340 

,  general  properties,  157 

,  hst  of  principal,  373 

suitable  for  after-mordanting,  373 

,  use  of  on  silk,  164 

, on  wool,  162 

Mordanting,  chemistry  of,  166 

—  dyes,  use  of  on  silk,  365 

—  of  wool,  341 

—  process,  chemistry,  of  343 
,  theory  of,  601 

—  salts,  chemical  action  of,  342 

—  with  alum,  347 
chrome,  344 

chrome,  theory  of,  603 

IMordants,  action  of  on  fibers,  166 
— ,  classificati  )n  of,  168 

—  dyes  on  various,  358 

—  elective  affinity  of  for  dyestuffs,  167 
— ,  metallic  salts  useful  for,  166 

—  for  acid  dyes  on  cotton,  205 

—  in  fabrics,  detection  of,  694 
Morin,  492 

Moritanic,  492 

Mother-of-pearl,  dyeing  of,  647 
Mulle  madder,  497 
Mungo,  526 
Myrobolans,  265 

Nanking  cotton,  519 
Naphthol  AS,  314,  322 

—  colors,  320 

,  apparatus  for  dyeing,  318 

,  fastness  of,  322 

Naphthol  D,  321 

—  LC,  325 

—  R,  313 

Naphthylamine  black,    method  of  dyeing, 
206 

—  ether,  311 


'    Napping  machine  for  knitgoods,  690 
Natural  dyes,  470 

,  action  of  on  cotton,  166 

—  flowers,  dyeing  of,  642 
Nerogene  D,  314,  330,  339 
Nettle  fiber,  575 
Neutral  dyes,  156 
Nigraniline,  451 
Nitrazol  C,  319 

Nitro-ortho-toluidine,  321,  332 
Nitro-para-toluidine,  321 
Nitro-phenetidine,  321,  333 
Nitrosamine  red,  319 
Nomenclature  of  dyestuffs,  222 
NW  salt  developer,  314 

Obermaier  dyeing  machine,  184 

Oil  mordants,  169 

Oils,  dyeing  of,  663 

Old  fustic,  495 

Olive  drab  color,  production  of,  392 

—  oil,  after-treatment  with,  283 
One-bath  mordanting  process,  358 
Orange  developer,  313 

Orcein,  499 

Orchil,  499 

Organic  acids,  action  of  on  cotton,  37 

Ortamine-brown,  462 

Ortho-amino-azo-toluene,  321 

Osage  orange,  495 

Overalls,  dyeing  of,  392 

Overhead  folder  for  piece  goods,  492 

Oxford  mixes,  533 

Oxidizing  agents,  action  of  on  fibers,  54 

—  machine  for  aniline  black,  466 
for  hosiery,  460 

—  mordant  for  logwood,  477 
Ozonite  bleaching  compound,  152 
Oxy  cellulose,  131 

Padding  dyeing  machine,  305 

—  jigger  for  sulphur  colors,  396 

—  machine,  323 

—  jigger  for  sulphur  colors,  396 

—  machine,  323 

for  sulphur  colors,  397 

with  hot  flue,  367 

— ,  steaming  and  washing  machine,  362 
Painting,  distinction  of  from  dyeing,  1 
Paper,  dyeing  of,  630 

—  pulp,  different  kinds  of,  630 


764 


INDEX 


Paper  pulp,  dyeing  of,  631 

—  staining,  632 
Pararnine-brown,  462 
Paranitraniline,  318 

—  brown,  331 

— ,  process  of  diazotizing,  327 

—  red,  322,  500 

—  S,  319 

Para  red,  action  of  copper  on,  324 

—  lakes,  656 

—  soap  PN,  319 
Para-toluidine,  321 
Paste  dyes,  storage  of,  208 
Pastel  colors,  514 
Patent  bark,  500 

—  salt,  266 

Pectin  matters  in  cotton,  89 
Perborin  bleaching  compounds,  152 
Perfumes,  dyeing  of,  663 
Permanganate  bleach  for  wool,  112 
Permutit  process  for  softening  water,  102 
Peroxide  bleach  on  wool,  properties,  112 

—  bleaching  baths,  preparation  of.  111 
Persian  berries,  508 

,  with  various  mordants,  508 

Persil  bleaching  compound,  152 
Persis,  500 
Phenol,  311 

—  developers,  309 
Phenylene-diamine,  311 
Phthalein  dyes,  156 

Picking    and    shearing    machine    on    silk 

goods,  577 
Picture  films,  dyeing  of,  645 
Piece  dyeing  kettle,  284 
Pigment  dyes,  169 
Plush  goods,  dyeing  of,  564 
Polishing     and     Sanding     macine       for 

worsteds,  580 
Poly-genetic  dyes,  340 
Polyzime,  use  of  on  cotton,  93 
Poplin,  dyeing  of,  554 
Potting  blacks,  356 

—  process  for  woolens,  66 
Practical  dyeing,  operations  in,  26 
Printing  inks,  648 

— ,  relation  of  to  dyeing,  2 
Prussian  blue,  522 
Psarski  raw  stock  machine,  178 
Pure  dye  black  on  silk,  482 
Purple  indigo  extract,  431 


Purpurin,  496 

Putting-out  machine  for  leather  dyeing, 

626 
Pyrolignite  of  iron,  after-treatment  with, 

283 

Quereetin,  500 
Quercitron,  500 

R  salt  developer,  314 

Rain  water,  use  of  in  dyeing,  215 

Ramie,  dyeing  of,  575 

— ,  general  methods  of  dyeing,  174 

Rapid  fast  dyes,  322 

Reaction  of  dyes  with  alum,  684 

ammonia,  683 

bleaching  powder,  684 

—  chrome,  684 

ferric  chloride,  684 

hydrochloric  acid,  683 

nitric  acid,  683 

soda  ash,  684 

sodium-hydrate,  683 

—  — stannous  chloride,  684 

sulphuric  acid,  682 

tannin  reagent,  684 

zinc  test,  685 

Recovered  wool,  526 

Red  developer,  313 

Redmonol,  dyeing  of,  647 

Reel  dyeing  machine,  300,  472 

Regain  in  conditioning,  59 

Resin  soap  for  cotton  bleaching,  122 

Resist  dyeing,  40 

for  cotton  goods,  276 

Resorcine,  311 

Revolving  tenter  machine,  601 

Rhea  fiber,  575 

Rhodamine,  method  of  dyeing  on  wool,  251 

Rhodes  dyeing  machine,  183 

River  water,  use  of  in  dyeing,  216 

Rolling  machine  for  cotton  pieces,  480 

piece  goods,  515 

Rosaniline  lakes,  653 

Rosin  soap,  653 

Rotary  pressing  machine,  483 

Royal  blue  spirits,  523 

Rubinic  acid,  503 

Rug  dyeing,  634 

—  yarns,  fastness  of  colors  for,  621 


INDEX 


765 


Saddening  dyed  colors,  35 

Safflower,  8 

Salt  in  dyes,  testing  for,  673 

Saxon  vat  for  indigo,  417 

Saxony  blue,  431 

Schappe  silk,  scouring  of,  100 

Schreinering  process  of  mercerizing,  53 

Scouring  machines  for  silk,  98 

Scrooping  silk,  35,  38,  219 

Sericin,  94 

Sewing  cotton,  fastness  of  colors  for,  622 

Shading  salt,  313 

Shearing  machine,  629 

for  woolen  goods,  655 

Shrinkage  of  wool  on  scouring,  71 
Shrinking  machine  for  cloth,  529 
Shoddy,  526 
— ,  fastness  of  colors  for,  619 

—  goods,  stripping  of,  527 
Short  bath  in  dyeing,  276 

Silicate  of  soda  in  cotton  bleaching,  122 
Silk,  action  of  acids  on,  38 

alkalies  on,  41 

chlorine  compounds  on,  56 

metallic  salts  on,  54 

peroxides  on,  56 

potassium  permanganate  on,  56 

tannic  acid  on,  39 

weighting  agents  on,  38 

bleaching  of  souple,  99 

boiling-off  of,.  96 

dyeing  mordant  colors  on,  164 

—  of  with  acid  colors,  197 

—  substantive  colors  on,  164 
effect  of  heat  on,  62 
general  methods  of  dyeing,  171 
impurities  in  raw,  94 
scouring  of  souple,  99 
test  for  weighing,  690 
use  of  basic  dyes  on,  249 

vat  colors  on,  164 

weighting  of,  200 

—  and  artificial  silk,  distinction  between, 
cotton,  estimation  of,  687 

tussah  silk,  distinction  between,  689 

—  cotton  goods,  aniline  black  on,  564    ■ 
,  dyeing  of,  560 

—  dyes,  increasing  fastness  of,  251 

—  finishing  machine,  541 
Silk-glue,  94 

SUk  noils,  dyeing  of,  365 


Silk  scouring,  proper  soaps  for,  97 

—  yarns,  apparatus  for  dyeing,  214 
Silver  cochineal,  505 

Singeing  machines,  123 

for  cotton,  121 

,  gas,  571 

Single-bath  mordanting,  351 

Size  for  dyeing,  285 

Sized  cotton  goods,  effect  of  heat  on,  62 

Sizing  machine  for  silk,  547 

skein  yarn,  685 

—  materials,  test  for,  691 
Skein  dyeing  machine,  206,  241 
for  indigo,  412 

silk,  215 

,  revolving  type,  211 

Skins,  dyeing  of,  634 

Silver  bleaching  machine,  201 

—  dyeing  machine,  192,  204 
Stubbing  and  printing  machine,  194 

—  dyeing  machine,  442 
—,- for,  198 

— ,  —  of,  190 

— ,  fastness  of  colors  for,  620 

Soap,  action  of  hard  water  on,  217 

—  mordant  for  cotton,  261 
Soaping  machines,  132 
Soaps,  characteristics  of,  87 

—  for  scouring  silk,  97 

wool,  87 

Soda  vat  for  indigo,  421 
Sodium  acetate  in  dyeing,  326 

—  bichromate,  344 

—  hydrosulphite,  414 

—  hypochlorite,  preparation  of,  135 

, by  electrolysis,  139 

,  use  of  in  cotton  bleaching,  134 

Sodium  perborate  as  a  bleaching  agent,  152 

—  peroxide,  110 

—  stannate,  after-treatment  with,  283 
,  use  of  in  dyeing  cotton,  205 

—  sulphite,  in  dyes,  testing  for,  676 
Soft  water,  definition  of,  216 
Softening  of  cotton,  130 

Solid  solution,  theory  of  dyeing,  585 
Soluble  alizarin  dyes,  354 

—  indigo,  431 

—  oil  in  cotton  dyeing,  278 

^  oils,  use  of  in  boiling-out  cotton,  92 
Solubility  of  dyes,  682 
Souple  silk,  96 


766 


INDEX 


Souring  operation  in  bleaching,  128 

Speck  dyeing,  188,  538 
Spirit  colors,  155 

—  lakes,  658 

Spirits  soluble  colors,  644 

Split  straw,  dyeing  of,  637 

Splitting  machine  for  warps,  233 

Spray  dyeing.  2 

Spun  silk,  dyeing  of  with  acid  colors,  199 

,  scouring  of,  100 

Standards  for  light  fastness,  609 
Standing  bath,  use  of,  187 

—  kettle,  187 

Stannic  chloride,  use  of  in  weighting  sUk, 
201 

, dyeing  cotton,  205 

, with  acid  dyes,  183 

Starch  in  dyes,  testing  for,  676 
Steam  black  with  aniline,  459 

—  finishing  machine,  693 

—  in  dyeing.  29 

Steamer  for  mordanted  cotton,  363 

sulphur  colors,  379 

Steaming  cottage  for  j'ams,  468 

Stencil  dyeing,  5 

Stock  dyed  colors,  characteristics  of,  189 

—  dyeing,  comparison  of  with  skein    dve- 

ing,  31 
Storage  of  dyestuffs,  207 
Storing  of  wool,  108 
Straw,  bleaching  of,  636 
— ,  dyemg  of,  636 
Stripping  of  dyed  colors,  237 
silk,  96 

—  shoddy,  methods  of,  237 
Substantive  colors,  methods  of  stripping, 

238 

—  dy&s,  action  of  on  cotton,  165 

,  after-treatment  of,  281 

,  bleeding  of,  276 

,  classes  of,  275 

,  list  of  principal,  290 

,  methods  of  appUcation,  281 

,  preparing  dyebath  for,  276 

,  solution  of,  275 

,  topped  with  basic  dyes,  278-284 

,  use  of,  for  silk,  164 

, ,  on  wool,  160 

on  cotton,  use  cf,  276 

jute,  577 

silk,  300 


Substantive  colors  on  silk,  list  of,  306 

wool,  298 

,  list  of,  306 

—  dyestufifs,  275 
Sudan  dyes,  664 

Sugar  in  dyes,  testing  for,  676 
Suint  in  wool,  71 

Sulphur  black,   correction  of  bronziness 
380 

dyeing  of,  378 

notes  on  dyeing,  382 

standing  baths  of,  382 

—  bleach,  defects  in,  109 

—  colors,  after-treatment  of,  380 

,  apparatus  for  dyeing,  393 

,  continuous  dyeing  of,  400 

,  dyeing  of  in  vat,  385 

,  —  on  foulard,  399 

,  fastness  of,  389 

.  foam  dyeing  of.  400 

,  machine  for  dyeing,  384 

,  method  for  dyeing,  384 

,  methods  of  stripping,  238 

,  softening  of,  386 

,  steaming  of,  384 

,  topping  of,  388 

,  in  dyeing  linen,  574 

—  dj'es,  action  of  on  cotton,  165 

,  after-treatment  of,  386 

,  characteristics  of,  375 

,  dissolving  of.  376 

.  exhaustion  of,  381 

,  history  of,  375 

,  list  of  principal,  401 

,  method  of  dyeing,  377 

on  jute,  577 

,  tendering  of  cloth  by,  379 

Sulphuric  acid,  use  of  in  dyeing,  184 
Sumac  tannin,  264 
Sweet  indigo  extract,  431 
Synthetic  indigo,  431 

Tabulation  of  fastness  test,  619 
Tannate  of  tin,  276 
Tannic  acid,  264 

,  action  of  on  fibers,  39 

Tannin,    methods   of  mordanting  cotton 
with,  257 

—  mordant,  application  of,  255 

—  mordants,  169 

Tanning  leather,  different  methods  of,  624 


INDEX 


767- 


Tannins,  263 

Tapestry  yarns,  fastness  of  colors  for,  621 

Tartar  emetic,  265 

,  use  of  in  fixing  tannin  mordant,  260 

—  substitute,  347 
Teasel  gig,  643 

Temperature  of  dyobath,    279 
Tenter,  with  automatic  clip,  518 
Tentering  and  drying  machine,  371 

—  machines,  133,  506 

Test  skeins,  preparation  of,  18 
Testing  of  dyestuffs,  666 
Tests  employed  in  dyeing,  678 
Textile  fibers,  action  of  acids  on,  36 
Textiles,  forms  of  dyeing,  31 
Theory  of  dyeing,  582 

compound  shades,  598 

mixed  fibers,  599 

pigment  colors,  596 

Thermometry,  706 

Thiazine  dyes,  247 

Thiazol  dyes,  247 

Thio  indigo  Red,  375 

Tie-dyeing  style,  4 

Tinting  of  bleached  cotton,  130 

wool,  109 

Tints,  dyeing  of  on  cotton,  280 
Tin-weighted  silk,  dyeing  of,  250 
Tin  mordants,  349 
Tissue  paper,  dyeing  of,    632 
Titanous  chloride,  238 
Tolidine,  321 
Toluylene-diamine,  314 
Tom-tom  machine,  459 
Top-chrome  method  of  dyeing,  354 
Tops,  dyeing  of,  190 
— ,  fastness  of  colors  for,  620 
— ,  scouring  of,  SO 
Tri-phenyleinethane  dyes,  247 
Turkey  red,  dyeing  of,  365 

oil  mordant,  262 

Turmeric,  508 

Tussah  silk,  dyeing  of  with  acid  colors, 
198 

■,  scouring  of,  100 

Typewriting  inks,  663 
Tyrian  purple,  8.  439 

Ultra-violet  lamp,  608 
Umbrella  cloth,  553 
Union  dyes,  300 


Union  goods,  action  of  dyes  on,  531 
— -  — ,  bleaching  of,  .530 
— -  — ,  dyeing  of,  300,  524 

,  fastness  of  colors  for,  623 

,  method  of  dyeing,  183 

—  — ,  properties  of,  530 
Unshrinkable  wool,  55 

Vacanceine  red,  320 
Vanadium,  in  dyeing  aniUne  black,  452 
Vapors  in  dyehouse,  removal  of,  29 
Vat  dyes,  action  of  on  cotton,  165 

—  — ,  classes  of,  405 

,  effect  of  kier  boiling  of,  406 

,  method  of  application,  443 

, dyeing.  408 

-,  use  of  on  silk,  164 

— •  — , wool,  1.72 

—  for  dj'eing  sulphur  colors,  376 
Vats  for  dyeing  yarn,  21 
Vegetable  dj^es,  155 

—  ivory,  645 

^'elvets,  fastness  of  colors  for,  622 
^'igoureux    system  of  printing  slubbing, 

194 
Viscolline  yarn,  579 
\'iscose  silk,  578 

Wall  paper  lakes,  648,  650 
Warp  dj'ed  union  goods,  532 

—  dyeing  machine,  218,    223,    235,    242, 

248,  249,  253,  387,  388,  390 
— for  aniline  black,  463 

—  yarn,  sizing  of,  85 

Washing  machine  for  hosiery,  147 

yarn.  336 

,  open  width,  315,  341 

—  machinery  in  cotton  bleaching,  129 

—  machines,  132 

Water,  amount  required  in  dyeing,  27 

— ,  effect  of  iron  in,  101 

— ,  treatment  of,  for  bleaching  and  dyeing, 

102 
— ,  in  dyeing,  26 
— ,  influence  of  in  dyeing,  215 
— ,  permanent  hardness  in,  100 
— ,  relation  of  to  wool  scouring,  100 
— ,  softening  with  zeolites,  103 
— ,  temporary  hardness  in,  100 
Waxes,  dyeing  of.  663 
Weaving  varns.  fastness  of  colors  for.  620 


768 


INDEX 


Weight  of  cotton,  increase  of  in  dyeing,  282 
Weighted  silk,  dyeing  of,  250 

,  effect  of  heat  on,  62 

Weighting  of  cotton  goods,  283 

—  silk,  200 
Weld,  507 
Woad,  410 

—  vat  for  indigo,  418 
Woaded  black,  476 

—  chip,  dyeing,  638 
Wood  chip,  dyeing,  638 
— ,  dyeing  of,  643 

Wool,  action  of  acid  on,  36 

alkalies  on,  40 

chlorine  on,  55 

—  —  hot  water  on,  63 

metallic  salts  on,  54 

oxidizing  agents  on,  56 

peroxides  on,  56 

potassium  permanganate  on,  56 

steam  on,  63 

tannic  acid  on,  40 

bleaching  of,  107 

carbonizing  of,  74 

effect  of  heat  on,  62 

general  methods  of  dyeing,  170 

impurities  in  raw,  71 

relation  of  various  dj-es  to,  160 

—  and  cotton,  estimation  of,  687 

silk,  estimation  of,  688 

dyeing,  properties  of,  160 

Wool-cotton  fabrics,  524 

Wool  dyeing,  in  loose  stock,  188 

,  proper  temperature  for,  160 

Wool-fat,  71 

Wool  fiber  under  microscope,  528 

—  oils,  composition  of,  77 

—  plush,  dyeing  of.  547 

—  scouring,  chemicals  employed  in,  72 
,  effect  of  water  in,  100 


Wool  scouring,  effect  of  temperature  on, 
72 

,  machinery  for,  73 

r,  use  of  alklai  in,  74 

,  with  soaps,  72 

Wool-silk  goods,  dyeing  of,  553 
Woolen  cloth,  methods  of  scouring,  82 

—  — ,  fastness  of  colors  for,  621 

—  — ,  scouring  machines  for,  81 
,  washing  machines  for,  80 

—  piece-goods,  carbonizing  of,  191 

—  — ,  dyeing  of,  191 

^  shearing  machine,  688 

—  yarn,  apparatus  for  d5'eing,  213 

,  containing  iron,  scouring  of,  80 

,  dj'eing  of,  190 

,  impurities  in,  75 

,  machines  for  scouring,  77 

,  oil  in,  76 

,  scouring  of,  75 

Worsted  yarns,  dyeing  of,  190 

,  scouring  of,  77 

Wringer  for  preparing  yarn,  320 

Xanthin,  496 
Xanthorhamnin,  508 

Yarn  dyeing  machine,  257 
,  vats  for,  21 

—  dryer,  360 . 

—  drying  machine.  457 

—  impregnating  ma.  hine,  457 

—  mordanting  machine,  348,  350 

—  reel  for  test  skeins,  19 

—  squeezer,  377 

—  wringing  machine,  468 
Yellow  developer,  313 
Young  fustic,  495 

Zinc-bisulphite  vat,  430 
Zinc  vat  for  indigo,  413,  426 


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